WO2019194260A1

WO2019194260A1 - High-shrinkage artificial fibroin fibers, method for producing same, and method for shrinking artificial fibroin fibers

Info

Publication number: WO2019194260A1
Application number: PCT/JP2019/014895
Authority: WO
Inventors: 潤一菅原; 森田　啓介; 中村　浩之
Original assignee: Ｓｐｉｂｅｒ株式会社; 小島プレス工業株式会社
Priority date: 2018-04-03
Filing date: 2019-04-03
Publication date: 2019-10-10
Also published as: JP2021167470A

Abstract

The purpose of the present invention is to provide high-shrinkage artificial fibroin fibers that have a sufficiently high shrinkage rate, that feel excellent against the skin and have excellent softness, and that can be produced safely. These high-shrinkage artificial fibroin fibers comprise a modified fibroin, are shrunken artificial fibroin fibers, and have a shrinkage rate of 2% or more as defined by the formula indicated below. Shrinkage rate = {1 – (length of artificial fibroin fibers that have become moist after being brought into contact with water/length of artificial fibroin fibers after being spun and prior to being brought into contact with water)} × 100 (%)

Description

High shrinkage artificial fibroin fiber, method for producing the same, and method for shrinking artificial fibroin fiber

The present invention relates to a high-shrinkage artificial fibroin fiber, a method for producing the same, and a method for shrinking an artificial fibroin fiber.

In general, fibers used for clothing, bedding, etc. are required to have a high touch. Silk, which is a kind of natural fibroin fiber, is known as a fiber that sufficiently satisfies the touch and has a high-class feeling.

Also, fibers used in clothing, bedding, etc. are required to have softness and heat retention. Therefore, silk used for clothing, bedding, and the like is subjected to, for example, shrink processing to increase bulkiness, thereby imparting flexibility and heat retention in some cases.

On the other hand, for example, synthetic fibers such as polyester fibers, polyamide fibers, and acrylic fibers are generally used for clothing, bedding, etc., and these synthetic fibers are brought into contact with boiling water and then left for 12 hours. The shrinkage rate of 40% or more is realized (Patent Document 1).

JP 2009-112003 A

However, conventional fibers hardly contracted only by being brought into contact with water, and sometimes contracted sufficiently only after being brought into contact with water and then dried.

Further, the shrinkage method described in Patent Document 1 is accompanied by a great danger in handling hot boiling water.

An object of the present invention is to provide a highly shrinkable artificial fibroin fiber having a sufficiently high shrinkage ratio, excellent in touch and flexibility, and capable of being produced safely, and a method for producing the same. Another object of the present invention is to provide a method for shrinking artificial fibroin fibers, which can safely obtain artificial fibroin fibers with a sufficiently high shrinkage rate.

The present invention relates to the following inventions, for example.
[1]
Shrinked artificial fibroin fiber comprising modified fibroin,
A highly shrinkable artificial fibroin fiber having a shrinkage rate defined by the following formula of 2% or more.
Shrinkage rate = {1− (length of artificial fibroin fiber made wet by contact with water / length of artificial fibroin fiber after spinning and before contact with water)} × 100 (%)
[2]
The high-shrinkage artificial fibroin fiber according to [1], wherein the modified fibroin is a modified spider silk fibroin.
[3]
The high-shrinkage artificial fibroin fiber according to [1] or [2], which is shrunk by contact with water having a boiling point below.
[4]
The high-shrinkage artificial fibroin fiber according to [3], wherein the temperature of the water is 10 to 90 ° C.
[5]
The high shrinkage artificial fibroin fiber according to [3] or [4], wherein the shrinkage rate is 7% or less.
[6]
A step of contacting an artificial fibroin fiber containing modified fibroin with water having a boiling point lower than that,
The manufacturing method of the high shrinkage artificial fibroin fiber whose shrinkage rate defined by a following formula is 2% or more.
Shrinkage rate = {1− (length of artificial fibroin fiber made wet by contact with water / length of artificial fibroin fiber after spinning and before contact with water)} × 100 (%)
[7]
The method for producing a high-shrinkage artificial fibroin fiber according to [6], wherein the modified fibroin is a modified spider silk fibroin.
[8]
The method for producing a high shrinkage artificial fibroin fiber according to [6] or [7], wherein the temperature of the water is 10 to 90 ° C.
[9]
The method for producing high-shrinkage artificial fibroin fiber according to any one of [6] to [8], wherein the shrinkage rate is 7% or less.
[10]
A step of contacting an artificial fibroin fiber containing modified fibroin with water having a boiling point lower than that,
A shrinkage method of artificial fibroin fiber, wherein the shrinkage rate defined by the following formula is 2% or more.
Shrinkage rate = {1− (length of artificial fibroin fiber made wet by contact with water / length of artificial fibroin fiber after spinning and before contact with water)} × 100 (%)
[11]
The method for shrinking artificial fibroin fiber according to [10], wherein the modified fibroin is a modified spider silk fibroin.
[12]
The method for shrinking artificial fibroin fiber according to [10] or [11], wherein the temperature of the water is 10 to 90 ° C.
[13]
The method for shrinking artificial fibroin fiber according to any one of [10] to [12], wherein the shrinkage ratio is 7% or less.
[14]
The modified fibroin comprises a domain sequence represented by Formula 1: [(A) _n motif-REP] _m ,
The domain sequence has an amino acid sequence with a reduced content of _n motif (A) corresponding to deletion of at least one or more (A) _n motifs compared to naturally occurring fibroin,
[1] to [5] The high shrinkage artificial fibroin fiber according to any one of [1] to [5], [6] to [9] [13] The method for shrinking artificial fibroin fiber according to any one of [13].
[In Formula 1, (A) _n motif represents an amino acid sequence composed of 2 to 27 amino acid residues, and (A) the number of alanine residues relative to the total number of amino acid residues in _n motif is 83% or more. . REP indicates an amino acid sequence composed of 10 to 200 amino acid residues. m represents an integer of 2 to 300. A plurality of (A) _n motifs may have the same or different amino acid sequences. Plural REPs may have the same amino acid sequence or different amino acid sequences. ]
[15]
The domain sequences, as compared to the naturally occurring fibroin, equivalent to at least the N-terminal side to the C-terminal one to three (A) _n motif every one (A) _n motifs lacking The high-shrinkage artificial fibroin fiber according to [14], the method for producing a high-shrinkage artificial fibroin fiber, or the method for shrinking an artificial fibroin fiber.
[16]
The domain sequences, as compared to the naturally occurring fibroin, at least the N-terminal side of two consecutive towards the C-terminal side from the (A) _n motif deletions, and one (A) _n motif deletions The high-shrinkage artificial fibroin fiber according to [14], the method for producing a high-shrinkage artificial fibroin fiber, or the method for shrinking an artificial fibroin fiber, which has an amino acid sequence corresponding to repetition in this order.
[17]
The modified fibroin comprises a domain sequence represented by Formula 1: [(A) _n motif-REP] _m ,
From the N-terminal side to the C-terminal side, compare the number of REP amino acid residues of two adjacent [(A) _n motif-REP] units in order, and the number of REP amino acid residues with a small number of amino acid residues. Is the sum of the number of amino acid residues of two adjacent [(A) _n motif-REP] units with a ratio of the number of amino acid residues of the other REP of 1.8 to 11.3. The high value according to any one of [1] to [5], wherein x / y is 50% or more, where x is the maximum value and y is the total number of amino acid residues in the domain sequence. Shrinkable artificial fibroin fiber, production method of high shrinkage artificial fibroin fiber according to any one of [6] to [9], or shrinkage of artificial fibroin fiber according to any one of [10] to [13] Method.
[In Formula 1, (A) _n motif represents an amino acid sequence composed of 2 to 27 amino acid residues, and (A) the number of alanine residues relative to the total number of amino acid residues in _n motif is 83% or more. . REP indicates an amino acid sequence composed of 10 to 200 amino acid residues. m represents an integer of 2 to 300. A plurality of (A) _n motifs may have the same or different amino acid sequences. Plural REPs may have the same amino acid sequence or different amino acid sequences. ]
[18]
The modified fibroin comprises a domain sequence represented by Formula 1: [(A) _n motif-REP] _m ,
Compared with naturally-occurring fibroin, the content of glycine residues corresponding to at least one or more glycine residues in REP was replaced with another amino acid residue in the domain sequence was reduced. Having an amino acid sequence,
[1] to [5] The high shrinkage artificial fibroin fiber according to any one of [1] to [5], [6] to [9] [13] The method for shrinking artificial fibroin fiber according to any one of [13].
[In Formula 1, (A) _n motif represents an amino acid sequence composed of 2 to 27 amino acid residues, and (A) the number of alanine residues relative to the total number of amino acid residues in _n motif is 83% or more. . REP indicates an amino acid sequence composed of 10 to 200 amino acid residues. m represents an integer of 2 to 300. A plurality of (A) _n motifs may have the same or different amino acid sequences. Plural REPs may have the same amino acid sequence or different amino acid sequences. ]
[19]
Compared with naturally occurring fibroin, the domain sequence is at least one or more of at least one motif sequence selected from GGX and GPGXX in REP (where X represents an amino acid residue other than glycine). The high-shrinkage artificial fibroin fiber according to [18], which has an amino acid sequence corresponding to substitution of one glycine residue in the motif sequence with another amino acid residue, Or the shrinkage | contraction method of artificial fibroin fiber.
[20]
The ratio of the motif sequence in which the glycine residue is substituted with another amino acid residue is 10% or more with respect to the entire motif sequence. The high-shrinkage artificial fibroin fiber and the high-shrinkage artificial fibroin fiber according to [19] Production method or shrinkage method of artificial fibroin fiber.
[21]
The modified fibroin comprises a domain sequence represented by Formula 1: [(A) _n motif-REP] _m ,
XGX contained in all REPs in the sequence excluding the sequence from the domain sequence to the most C-terminal side (A) _n motif to the C-terminus of the domain sequence (where X is an amino acid residue other than glycine) The total number of amino acid residues in the amino acid sequence consisting of z) is z, and the domain sequence is located at the most C-terminal side (A) in the sequence excluding the sequence from the _n motif to the C-terminus of the domain sequence The high-shrinkage artificial fibroin fiber according to any one of [1] to [5], wherein z / w is 50.9% or more, where w is the total number of amino acid residues in [6] to [6] [9] The method for producing high-shrinkage artificial fibroin fiber according to any one of [9], or the method for shrinking artificial fibroin fiber according to any one of [10] to [13].
[In Formula 1, (A) _n motif represents an amino acid sequence composed of 2 to 27 amino acid residues, and (A) the number of alanine residues relative to the total number of amino acid residues in _n motif is 83% or more. . REP indicates an amino acid sequence composed of 10 to 200 amino acid residues. m represents an integer of 2 to 300. A plurality of (A) _n motifs may have the same or different amino acid sequences. Plural REPs may have the same amino acid sequence or different amino acid sequences. ]
[22]
The modified fibroin corresponds to the substitution of one or more glycine residues in REP with another amino acid residue as compared with naturally occurring fibroin, and in addition, one or more amino acid residues The high-shrinkage artificial fibroin fiber and the method for producing the high-shrinkage artificial fibroin fiber according to any one of [18] to [21], which have an amino acid sequence corresponding to substitution, deletion, insertion and / or addition of Or shrinkage method of artificial fibroin fiber.
[23]
The modified fibroin comprises a domain sequence represented by Formula 1: [(A) _n motif-REP] _m ,
The domain sequence has one or more amino acid residues in REP substituted with amino acid residues having a higher hydrophobicity index and / or one or more hydrophobicity in REP compared to naturally occurring fibroin. Having an amino acid sequence including a region having a large hydrophobic index, which corresponds to insertion of an amino acid residue having a large sex index,
[1] to [5] The high shrinkage artificial fibroin fiber according to any one of [1] to [5], [6] to [9] [13] The method for shrinking artificial fibroin fiber according to any one of [13].
[In Formula 1, (A) _n motif represents an amino acid sequence composed of 2 to 27 amino acid residues, and (A) the number of alanine residues relative to the total number of amino acid residues in _n motif is 83% or more. . REP indicates an amino acid sequence composed of 10 to 200 amino acid residues. m represents an integer of 2 to 300. A plurality of (A) _n motifs may have the same or different amino acid sequences. Plural REPs may have the same amino acid sequence or different amino acid sequences. ]
[24]
The high-shrinkage artificial fibroin fiber, the method for producing high-shrinkage artificial fibroin fiber according to [23], or the artificial fibroin, wherein the region having a large local hydrophobicity index is composed of continuous 2 to 4 amino acid residues Fiber shrinkage method.
[25]
The amino acid residue having a large hydrophobicity index is selected from isoleucine (I), valine (V), leucine (L), phenylalanine (F), cysteine (C), methionine (M) and alanine (A). 23] or [24], a highly shrinkable artificial fibroin fiber, a method for producing a highly shrinkable artificial fibroin fiber, or a method for shrinking an artificial fibroin fiber.
[26]
The modified fibroin comprises a domain sequence represented by Formula 1: [(A) _n motif-REP] _m ,
(A) The average of the hydrophobicity index of four consecutive amino acid residues in all REPs included in the sequence excluding the sequence from the _n motif to the C terminus of the domain sequence from the domain sequence. P is the total number of amino acid residues contained in the region where the value is 2.6 or more, and the sequence from the (A) _n motif located at the most C-terminal side to the C-terminus of the domain sequence is excluded from the domain sequence. The high shrinkage artificial fibroin fiber according to any one of [1] to [5], wherein p / q is 6.2% or more, where q is the total number of amino acid residues contained in the sequence, [6] to [9] The method for producing high-shrinkage artificial fibroin fibers according to any one of [6] to [9], or the method for shrinking artificial fibroin fibers according to any one of [10] to [13].
[In Formula 1, (A) _n motif represents an amino acid sequence composed of 2 to 27 amino acid residues, and (A) the number of alanine residues relative to the total number of amino acid residues in _n motif is 83% or more. . REP indicates an amino acid sequence composed of 10 to 200 amino acid residues. m represents an integer of 2 to 300. A plurality of (A) _n motifs may have the same or different amino acid sequences. Plural REPs may have the same amino acid sequence or different amino acid sequences. ]
[27]
In the modified fibroin, one or more amino acid residues in REP are replaced with amino acid residues having a higher hydrophobicity index and / or one or more hydrophobic groups in REP compared to naturally occurring fibroin. In addition to corresponding to insertion of an amino acid residue having a large sex index, it further has an amino acid sequence corresponding to substitution, deletion, insertion and / or addition of one or more amino acid residues, [23 ] The high shrinkage artificial fibroin fiber, the method for producing the high shrinkage artificial fibroin fiber, or the method for shrinking the artificial fibroin fiber according to any one of [1] to [26].
[28]
The modified fibroin comprises a domain sequence represented by Formula 1: [(A) _n motif-REP] _m or Formula 2: [(A) _n motif-REP] _m- (A) _n motif;
Glutamine residue content corresponding to the domain sequence having one or more glutamine residues in REP deleted or substituted with other amino acid residues compared to naturally occurring fibroin Has a reduced amino acid sequence,
[1] to [5] The high shrinkage artificial fibroin fiber according to any one of [1] to [5], [6] to [9] [13] The method for shrinking artificial fibroin fiber according to any one of [13].
[In Formula 1 and Formula 2, (A) _n motif represents an amino acid sequence composed of 2 to 27 amino acid residues, and (A) the number of alanine residues is 80% with respect to the total number of amino acid residues in _n motif. That's it. REP indicates an amino acid sequence composed of 10 to 200 amino acid residues. m represents an integer of 2 to 300. A plurality of (A) _n motifs may have the same or different amino acid sequences. Plural REPs may have the same amino acid sequence or different amino acid sequences. ]
[29]
The high-shrinkage artificial structure according to [28], wherein the modified fibroin includes a GPGXX (where X represents an amino acid residue other than a glycine residue) motif in REP, and the content ratio of the GPGXX motif is 10% or more. A method for producing fibroin fiber, high shrinkage artificial fibroin fiber, or a method for shrinking artificial fibroin fiber.
[30]
The method for producing high-shrinkage artificial fibroin fiber, high-shrinkage artificial fibroin fiber, or method for shrinking artificial fibroin fiber according to [28] or [29], wherein the modified fibroin has a glutamine residue content of 9% or less.
[31]
The other amino acid residues are isoleucine (I), valine (V), leucine (L), phenylalanine (F), cysteine (C), methionine (M), alanine (A), glycine (G), threonine ( Any one of [28] to [30], which is an amino acid residue selected from the group consisting of T), serine (S), tryptophan (W), tyrosine (Y), proline (P), and histidine (H) One of the high shrinkage artificial fibroin fibers, the method for producing the high shrinkage artificial fibroin fibers, or the method for shrinking the artificial fibroin fibers.
[32]
The modified fibroin is a highly shrinkable artificial fibroin fiber according to any one of [28] to [31], wherein the hydrophobicity of REP is −0.8 or more, Shrinking method of artificial fibroin fiber.
[33]
In addition to the modified fibroin corresponding to the deletion of one or more glutamine residues in REP or substitution with other amino acid residues as compared to naturally occurring fibroin, The high-shrinkage artificial fibroin fiber or high-shrinkage artificial fiber according to any one of [28] to [32], which has an amino acid sequence corresponding to substitution, deletion, insertion and / or addition of a plurality of amino acid residues A method for producing fibroin fibers or a method for shrinking artificial fibroin fibers.
[34]
The high-shrinkage artificial fibroin fiber according to any one of [1] to [5], wherein the modified fibroin has a limiting oxygen index (LOI) value of 26.0 or more, and any of [6] to [9] The method for producing high shrinkage artificial fibroin fiber according to any one of the above, or the method for shrinking artificial fibroin fiber according to any one of [10] to [13].
[35]
The high-shrinkage artificial fibroin fiber according to any one of [1] to [5], wherein the modified fibroin has a maximum moisture absorption exotherm calculated according to the following formula A of more than 0.025 ° C./g, [6] The method for producing high-shrinkage artificial fibroin fibers according to any one of [9] to [9], or the method for shrinking artificial fibroin fibers according to any one of [10] to [13].
Formula A: Maximum moisture absorption exotherm = {(maximum value of sample temperature when the sample is placed in a low humidity environment until the sample temperature reaches equilibrium and then transferred to a high humidity environment) − (sample Sample temperature when placed in a low-humidity environment until the temperature reaches equilibrium and then moved to a high-humidity environment)} (° C.) / Sample weight (g)
[In Formula A, a low humidity environment means an environment with a temperature of 20 ° C. and a relative humidity of 40%, and a high humidity environment means an environment with a temperature of 20 ° C. and a relative humidity of 90%. ]

According to the present invention, it is possible to provide a high-shrinkage artificial fibroin fiber that has a sufficiently high shrinkage rate, is excellent in touch and flexibility, and can be produced safely, and a method for producing the same. According to the present invention, it is also possible to provide a method for shrinking artificial fibroin fibers, which can safely obtain artificial fibroin fibers with a sufficiently high shrinkage rate.

It is a schematic diagram which shows an example of the domain arrangement | sequence of a modified fibroin. It is a figure which shows distribution of the value of z / w (%) of the fibroin derived from nature. It is a figure which shows distribution of the value of x / y (%) of naturally derived fibroin. It is a schematic diagram which shows an example of the domain arrangement | sequence of a modified fibroin. It is a schematic diagram which shows an example of the domain arrangement | sequence of a modified fibroin. It is explanatory drawing which shows roughly an example of the spinning apparatus for manufacturing artificial fibroin fiber. It is explanatory drawing which shows roughly an example of the manufacturing apparatus for manufacturing a highly shrinkable artificial fibroin fiber. It is explanatory drawing which shows roughly an example of the manufacturing apparatus for manufacturing a highly shrinkable artificial fibroin fiber. It is a graph which shows an example of the result of a hygroscopic exothermic test.

Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

[High shrinkage artificial fibroin fiber]
The highly contracted artificial fibroin fiber according to the present invention is a contracted artificial fibroin fiber containing modified fibroin. The high shrinkage artificial fibroin fiber according to this embodiment has a shrinkage rate defined by the following formula of 2% or more.
Shrinkage rate = {1− (length of artificial fibroin fiber made wet by contact with water / length of artificial fibroin fiber after spinning and before contact with water)} × 100 (%)

<Modified fibroin>
The modified fibroin according to the present embodiment has a domain sequence represented by Formula 1: [(A) _n motif-REP] _m or Formula 2: [(A) _n motif-REP] _m- (A) _n motif. It is a protein containing. In the modified fibroin, an amino acid sequence (N-terminal sequence and C-terminal sequence) may be further added to either one or both of the N-terminal side and the C-terminal side of the domain sequence. The N-terminal sequence and the C-terminal sequence are not limited to these, but are typically regions having no amino acid motif repeat characteristic of fibroin and consisting of about 100 amino acids.

As used herein, “modified fibroin” means an artificially produced fibroin (artificial fibroin). The modified fibroin may be a fibroin whose domain sequence is different from the amino acid sequence of naturally occurring fibroin or may be the same as the amino acid sequence of naturally occurring fibroin. “Natural fibroin” as used herein is also represented by Formula 1: [(A) _n motif-REP] _m or Formula 2: [(A) _n motif-REP] _m- (A) _n motif. A protein comprising a domain sequence to be processed.

The “modified fibroin” may be one that uses the amino acid sequence of naturally-occurring fibroin as it is, or a modified amino acid sequence based on the amino acid sequence of naturally-occurring fibroin (for example, a cloned naturally-derived fibroin). The amino acid sequence may be modified by modifying the gene sequence of fibroin), or artificially designed and synthesized without relying on natural fibroin (for example, a nucleic acid encoding the designed amino acid sequence). It may be one having a desired amino acid sequence by chemical synthesis.

In the present specification, the “domain sequence” refers to a fibroin-specific crystal region (typically corresponding to the (A) _n motif in the amino acid sequence) and an amorphous region (typically in the REP of the amino acid sequence). Amino acid sequence that gives rise to the following formula: Formula 1: [(A) _n motif-REP] _m or Formula 2: [(A) _n motif-REP] _m- (A) amino acid represented by _n motif Means an array. Here, (A) _n motif represents an amino acid sequence mainly composed of alanine residues, and the number of amino acid residues is 2 to 27. (A) The _number of amino acid residues of the _n motif may be an integer of 2 to 20, 4 to 27, 4 to 20, 8 to 20, 10 to 20, 4 to 16, 8 to 16, or 10 to 16 . In addition, the ratio of the number of alanine residues to the total number of amino acid residues in the (A) _n motif may be 40% or more, such as 60% or more, 70% or more, 80% or more, 83% or more, 85% or more, It may be 86% or more, 90% or more, 95% or more, or 100% (meaning that it is composed only of alanine residues). A plurality of (A) _n motifs present in the domain sequence may be composed of at least seven alanine residues alone. REP indicates an amino acid sequence composed of 2 to 200 amino acid residues. REP may be an amino acid sequence composed of 10 to 200 amino acid residues, 10 to 40, 10 to 60, 10 to 80, 10 to 100, 10 to 120, 10 to 140, 10 to 160, or It may be an amino acid sequence composed of 10 to 180 amino acid residues. m represents an integer of 2 to 300, 8 to 300, 10 to 300, 20 to 300, 40 to 300, 60 to 300, 80 to 300, 100 to 300, 10 to 200, 20 to 200, 20 to 180, It may be an integer from 20 to 160, 20 to 140, or 20 to 120. A plurality of (A) _n motifs may have the same or different amino acid sequences. Plural REPs may have the same amino acid sequence or different amino acid sequences.

The modified fibroin according to the present embodiment is, for example, an amino acid sequence corresponding to, for example, substitution, deletion, insertion and / or addition of one or a plurality of amino acid residues to the cloned gene sequence of naturally derived fibroin. It can be obtained by modifying the above. Substitution, deletion, insertion and / or addition of amino acid residues can be carried out by methods well known to those skilled in the art such as partial-directed mutagenesis. Specifically, Nucleic Acid Res. 10, 6487 (1982), Methods in Enzymology, 100, 448 (1983), and the like.

Naturally-derived fibroin is a protein containing a domain sequence represented by Formula 1: [(A) _n motif-REP] _m or Formula 2: [(A) _n motif-REP] _m- (A) _n motif. Specific examples include fibroin produced by insects or spiders.

Examples of fibroin produced by insects include, for example, Bombyx mori, Kwako (Bombyx mandarina), Tenaea (Antheraea palaniii), and 楓蚕 (Eriothyraminey). ), Silkworms produced by silkworms, such as Samia cythia, chestnut worms (Caligula japonica), Chuser moth (Antherea mylitta), Antheraea assama, and vespax (Vespaxia spp.) Hornet silk protein.

More specific examples of fibroin produced by insects include silkworm fibroin L chain (GenBank accession number M76430 (base sequence) and AAA27840.1 (amino acid sequence)).

Fibroin produced by spiders includes, for example, spiders belonging to the genus spider (Araneus spp.) Such as the spider spider, the spider spider, the red spider spider, and the bean spider, the genus spiders of the genus Araneus, the spider spider spider, the spider spider genus e Spiders, spiders such as spiders, spiders belonging to the genus Spider, spiders belonging to the genus Pronos, spiders belonging to the genus Trinofunda, such as Torinofundamas (genus Cyrtarachne) Spiders belonging to the genus (Gasteracantha), spiders belonging to the genus Spider (Ordgarius genus), such as the spiders, the spiders, and the spiders belonging to the genus Ordgarius Spiders belonging to the genus Argiope, such as the genus Argiope, spiders belonging to the genus Arachnura, such as the white-tailed spider, spiders belonging to the genus Acusilas such as the common spider, the spider belonging to the genus Acusilas, and the genus Spider Spiders belonging to (genus Cytophora), spiders belonging to the genus Spider belonging to the genus Spider (genus Poltys) such as spiders, genus Spider, spiders belonging to the genus Spider belonging to the genus Cyclosa (genus Cyclosa), and spiders belonging to the genus Cyclosa (genus Cyclosa) Spider silk proteins produced by spiders belonging to the genus Chorizopes), and Asina, such as Asagaaga spider, Yasagata Asaga spider, Harabiro Ashida spider and Urokoa Asaga spider Spiders belonging to the genus Tetragnata, spiders belonging to the genus Spider genus (Leucage genus) such as the white spider spider and the white spider spider, the spider genus belonging to the genus Spider genus (Nephila spp. Spiders belonging to the genus Azumigumi (Menosira), spiders belonging to the genus Dyschiriognatha (genus Dyschiriognatha) such as the common spider spider, the black spider spider, the genus Spider genus belonging to the genus Spider belonging to the genus and the genus Spider belonging to the genus Spider belonging to the genus, and Produced by spiders belonging to the family Tetragnathidae such as spiders belonging to the genus Prostenops Examples include spider silk protein. Examples of the spider silk protein include dragline proteins such as MaSp (MaSp1 and MaSp2) and ADF (ADF3 and ADF4), MiSp (MiSp1 and MiSp2), and the like.

More specific examples of spider silk proteins produced by spiders include, for example, fibroin-3 (adf-3) [derived from Araneus diadematus] (GenBank accession numbers AAC47010 (amino acid sequence), U47855 (base sequence)), fibroin-4 (adf-4) [derived from Araneus diadematus] (GenBank accession number AAC47011 (amino acid sequence), U47856 (base sequence)), dragline silk protein spiroin 1 [derived from Nephila clavipes] (GenBank amino acid sequence 4) ), U37520 (base sequence)), major ampulate spidro n 1 [derived from Latroductus hesperus] (GenBank accession number ABR68856 (amino acid sequence), EF595246 (base sequence)), dragline silk protein spidrin 2 [derived from Nephila clavata (GenBank accession number AAL32 base sequence 45 AAL32 base sequence amino acid 44, amino acid sequence 44 AAL47) )), Major ampulerate spiroin 1 [from Euprosthenops australis] (GenBank accession numbers CAJ00428 (amino acid sequence), AJ973155 (base sequence)), and major amplospiroid 2 [Euprostenaplas ] (GenBank accession number CAM32249.1 (amino acid sequence), AM490169 (base sequence)), minor sample silk protein 1 [Nephila clubs] (GenBank accession number AAC145891 (amino acid sequence)), minor sample 2 [minolampulapple 2] Nephila clavies] (GenBank accession number AAC14591.1 (amino acid sequence)), minor sample spirodin-like protein [Nephilegenes cruentata] (GenBank accession number ABR37278.1 (amino acid sequence), etc.

More specific examples of naturally derived fibroin include fibroin whose sequence information is registered in NCBI GenBank. For example, spidin, sample, fibroin, “silk and polypeptide”, or “silk and protein” is described as a keyword in DEFINITION from sequences including INV as DIVISION among the sequence information registered in NCBI GenBank. It can be confirmed by extracting a character string of a specific product from the sequence, CDS, and a sequence in which the specific character string is described from SOURCE to TISSUE TYPE.

The modified fibroin according to the present embodiment may be a modified silk fibroin (a modified amino acid sequence of a silk protein produced by a silkworm), or a modified spider silk fibroin (a spider silk protein produced by a spider). It may be a modified amino acid sequence). As the modified fibroin, a modified spider silk fibroin is preferable. The modified spider silk fibroin is excellent in heat retention, moisture absorption heat generation and / or flame retardancy.

Specific examples of the modified fibroin include a modified fibroin derived from a large sphincter bookmarker protein produced in a large spider gland (first modified fibroin), a domain sequence with a reduced content of glycine residues Modified fibroin (second modified fibroin) having (A) modified fibroin (third modified fibroin) having a domain sequence with reduced content of _n motif, content of glycine residue, and (A) _n Modified fibroin with reduced motif content (fourth modified fibroin), modified fibroin having a domain sequence that includes a region with a large hydrophobic index locally (fifth modified fibroin), and glutamine residue content Are modified fibroins having a reduced domain sequence (sixth modified fibroin).

Examples of the first modified fibroin include a protein comprising a domain sequence represented by Formula 1: [(A) _n motif-REP] _m . In the first modified fibroin, (A) the _number of amino acid residues of the _n motif is preferably an integer of 3 to 20, more preferably an integer of 4 to 20, still more preferably an integer of 8 to 20, and an integer of 10 to 20 Is more preferable, an integer of 4 to 16 is still more preferable, an integer of 8 to 16 is particularly preferable, and an integer of 10 to 16 is most preferable. In the first modified fibroin, in Formula 1, the number of amino acid residues constituting REP is preferably 10 to 200 residues, more preferably 10 to 150 residues, and 20 to 100 residues. More preferably, it is more preferably 20 to 75 residues. In the first modified fibroin, the total number of glycine residues, serine residues and alanine residues contained in the amino acid sequence represented by the formula 1: [(A) _n motif-REP] _m is an amino acid residue. The total number is preferably 40% or more, more preferably 60% or more, and even more preferably 70% or more.

The first modified fibroin comprises an amino acid sequence unit represented by Formula 1: [(A) _n motif-REP] _m , and the C-terminal sequence is represented by any one of SEQ ID NOs: 1 to 3 or It may be a polypeptide that is an amino acid sequence having 90% or more homology with the amino acid sequence shown in any one of SEQ ID NOs: 1 to 3.

The amino acid sequence shown in SEQ ID NO: 1 is identical to the amino acid sequence consisting of 50 amino acids at the C-terminal of the amino acid sequence of ADF3 (GI: 1263287, NCBI), and the amino acid sequence shown in SEQ ID NO: 2 is the sequence The amino acid sequence shown in SEQ ID NO: 1 is identical to the amino acid sequence obtained by removing 20 residues from the C-terminal, and the amino acid sequence shown in SEQ ID NO: 3 has 29 residues removed from the C-terminal of the amino acid sequence shown in SEQ ID NO: 1. It is identical to the amino acid sequence.

As a more specific example of the first modified fibroin, (1-i) an amino acid sequence represented by SEQ ID NO: 4 (recombinant spider silk protein ADF3KaiLargeNRSH1), or (1-ii) an amino acid sequence represented by SEQ ID NO: 4 and 90 Mention may be made of modified fibroin comprising an amino acid sequence having a sequence identity of at least%. The sequence identity is preferably 95% or more.

The amino acid sequence represented by SEQ ID NO: 4 is an amino acid sequence of ADF3 in which an amino acid sequence (SEQ ID NO: 5) consisting of a start codon, a His10 tag and an HRV3C protease (Human rhinovirus 3C protease) recognition site is added to the N-terminus. The 13th repeat region was increased to approximately double, and the translation was mutated to terminate at the 1154th amino acid residue. The C-terminal amino acid sequence of the amino acid sequence shown in SEQ ID NO: 4 is identical to the amino acid sequence shown in SEQ ID NO: 3.

The modified fibroin (1-i) may be composed of the amino acid sequence represented by SEQ ID NO: 4.

The second modified fibroin has an amino acid sequence whose domain sequence has a reduced content of glycine residues compared to naturally occurring fibroin. It can be said that the second modified fibroin has an amino acid sequence corresponding to at least one or more glycine residues in REP substituted with another amino acid residue as compared with naturally occurring fibroin. .

The second modified fibroin has a domain sequence of GGX and GPGXX in REP (where G is a glycine residue, P is a proline residue, and X is an amino acid residue other than glycine) as compared to naturally occurring fibroin. In which at least one glycine residue in at least one or more of the motif sequences is substituted with another amino acid residue. May be.

In the second modified fibroin, the ratio of the motif sequence in which the above glycine residue is replaced with another amino acid residue may be 10% or more with respect to the entire motif sequence.

The second modified fibroin comprises a domain sequence represented by Formula 1: [(A) _n motif-REP] _m , and is located on the most C-terminal side from the domain sequence (A) from the _n motif to the domain sequence. The total number of amino acid residues in the amino acid sequence consisting of XGX (where X represents an amino acid residue other than glycine) contained in all REPs in the sequence excluding the sequence up to the C-terminal of (A) _where the total number of amino acid residues in the sequence excluding the sequence from the _n motif located at the most C-terminal side to the C-terminal of the domain sequence is w, z / w is 30% or more, It may have an amino acid sequence that is 40% or more, 50% or more, or 50.9% or more. (A) The number of alanine residues relative to the total number of amino acid residues in the _n motif may be 83% or more, preferably 86% or more, more preferably 90% or more, and 95% or more. More preferably, it is 100% (meaning that it is composed only of alanine residues).

The second modified fibroin is preferably one in which the content ratio of the amino acid sequence consisting of XGX is increased by substituting one glycine residue of the GGX motif with another amino acid residue. In the second modified fibroin, the content ratio of the amino acid sequence consisting of GGX in the domain sequence is preferably 30% or less, more preferably 20% or less, still more preferably 10% or less, % Or less is even more preferable, 4% or less is even more preferable, and 2% or less is particularly preferable. The content ratio of the amino acid sequence consisting of GGX in the domain sequence can be calculated by the same method as the method for calculating the content ratio (z / w) of the amino acid sequence consisting of XGX below.

The method for calculating z / w will be described in more detail. First, in a fibroin (modified fibroin or naturally-occurring fibroin) containing a domain sequence represented by Formula 1: [(A) _n motif-REP] _m , (A) _n located closest to the C-terminal side from the domain sequence An amino acid sequence consisting of XGX is extracted from all REPs included in the sequence excluding the sequence from the motif to the C-terminal of the domain sequence. The total number of amino acid residues constituting XGX is z. For example, when 50 amino acid sequences consisting of XGX are extracted (no duplication), z is 50 × 3 = 150. Also, for example, when there is an X (center X) included in two XGXs as in the case of an amino acid sequence consisting of XGXGX, the calculation is performed by subtracting the overlap (in the case of XGXGX, it is 5 amino acid residues). is there). w is the total number of amino acid residues contained in the sequence excluding the sequence from the domain sequence to the most C-terminal (A) _n motif to the C-terminus of the domain sequence. For example, in the case of the domain sequence shown in FIG. 1, w is 4 + 50 + 4 + 100 + 4 + 10 + 4 + 20 + 4 + 30 = 230 (excluding the (A) _n motif located closest to the C-terminal side). Next, z / w (%) can be calculated by dividing z by w.

Here, z / w in naturally derived fibroin will be described. First, as described above, when a fibroin whose amino acid sequence information is registered in NCBI GenBank was confirmed by a method exemplified, 663 types of fibroin (of which 415 types were derived from spiders) were extracted. Of all the extracted fibroin, it is derived from the natural origin including the domain sequence represented by Formula 1: [(A) _n motif-REP] _m , and the content ratio of the amino acid sequence consisting of GGX in fibroin is 6% or less Z / w was calculated from the amino acid sequence of the fibroin by the calculation method described above. The result is shown in FIG. The horizontal axis in FIG. 2 indicates z / w (%), and the vertical axis indicates frequency. As is clear from FIG. 2, z / w in naturally derived fibroin is less than 50.9% (the highest is 50.86%).

In the second modified fibroin, z / w is preferably 50.9% or more, more preferably 56.1% or more, further preferably 58.7% or more, and 70% or more. It is still more preferable that it is 80% or more. Although there is no restriction | limiting in particular in the upper limit of z / w, For example, 95% or less may be sufficient.

The second modified fibroin is obtained by, for example, modifying a cloned natural fibroin gene sequence so as to encode another amino acid residue by substituting at least a part of a base sequence encoding a glycine residue. Obtainable. At this time, one glycine residue in GGX motif and GPGXX motif may be selected as a glycine residue to be modified, or substitution may be performed so that z / w is 50.9% or more. In addition, for example, an amino acid sequence satisfying the above-described aspect can be designed from the amino acid sequence of naturally derived fibroin, and a nucleic acid encoding the designed amino acid sequence can be obtained by chemical synthesis. In any case, in addition to the modification corresponding to the substitution of the glycine residue in REP with another amino acid residue from the amino acid sequence of naturally occurring fibroin, one or more amino acid residues are further substituted or deleted. The amino acid sequence corresponding to the insertion and / or addition may be modified.

The other amino acid residue is not particularly limited as long as it is an amino acid residue other than a glycine residue, but a valine (V) residue, a leucine (L) residue, an isoleucine (I) residue, M) hydrophobic amino acid residues such as proline (P) residue, phenylalanine (F) residue and tryptophan (W) residue, glutamine (Q) residue, asparagine (N) residue, serine (S ) Residues, hydrophilic amino acid residues such as lysine (K) residues and glutamic acid (E) residues are preferred, and valine (V) residues, leucine (L) residues, isoleucine (I) residues, F) residue and glutamine (Q) residue are more preferred, and glutamine (Q) residue is still more preferred.

More specific examples of the second modified fibroin include (2-i) SEQ ID NO: 6 (Met-PRT380), SEQ ID NO: 7 (Met-PRT410), SEQ ID NO: 8 (Met-PRT525) or SEQ ID NO: 9 (Met -PRT799), or (2-ii) an amino acid sequence having 90% or more sequence identity with the amino acid sequence shown in SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8 or SEQ ID NO: 9, Mention may be made of modified fibroin.

The modified fibroin (2-i) will be described. The amino acid sequence represented by SEQ ID NO: 6 is obtained by substituting GQX for all GGX in the REP of the amino acid sequence represented by SEQ ID NO: 10 (Met-PRT313) corresponding to naturally occurring fibroin. The amino acid sequence represented by SEQ ID NO: 7 is the amino acid sequence represented by SEQ ID NO: 6, wherein every two (A) _n motifs are deleted from the N-terminal side to the C-terminal side, and further before the C-terminal sequence. One [(A) _n motif-REP] is inserted into the. The amino acid sequence represented by SEQ ID NO: 8 has two alanine residues inserted at the C-terminal side of each (A) _n motif of the amino acid sequence represented by SEQ ID NO: 7, and a part of glutamine (Q) residues. Substituted with a serine (S) residue and a part of the amino acid at the C-terminal side was deleted so as to be almost the same as the molecular weight of SEQ ID NO: 7. The amino acid sequence represented by SEQ ID NO: 9 is a region of 20 domain sequences present in the amino acid sequence represented by SEQ ID NO: 7 (however, several amino acid residues on the C-terminal side of the region are substituted). Is obtained by adding a predetermined hinge sequence and a His tag sequence to the C-terminus of the sequence repeated four times.

The value of z / w in the amino acid sequence represented by SEQ ID NO: 10 (corresponding to naturally occurring fibroin) is 46.8%. The z / w values of the amino acid sequence shown by SEQ ID NO: 6, the amino acid sequence shown by SEQ ID NO: 7, the amino acid sequence shown by SEQ ID NO: 8, and the amino acid sequence shown by SEQ ID NO: 9 are 58.7%, 70.1%, 66.1% and 70.0%. In addition, the value of x / y at the ratio of the amino acid sequences shown in SEQ ID NO: 10, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8 and SEQ ID NO: 9 (described later) 1: 1.8 to 11.3 is: 15.0%, 15.0%, 93.4%, 92.7% and 89.8%, respectively.

The modified fibroin (2-i) may be composed of the amino acid sequence represented by SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8 or SEQ ID NO: 9.

The modified fibroin (2-ii) includes an amino acid sequence having 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8 or SEQ ID NO: 9. The modified fibroin of (2-ii) is also a protein containing a domain sequence represented by Formula 1: [(A) _n motif-REP] _m . The sequence identity is preferably 95% or more.

The modified fibroin of (2-ii) has 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8 or SEQ ID NO: 9, and is contained in REP (XGX ( Where X is an amino acid residue other than glycine.) Z / w where z is the total number of amino acid residues of the amino acid sequence consisting of z and w is the total number of amino acid residues of REP in the domain sequence. Is preferably 50.9% or more.

The second modified fibroin may contain a tag sequence at one or both of the N-terminal and C-terminal. This makes it possible to isolate, immobilize, detect and visualize the modified fibroin.

Examples of tag sequences include affinity tags that use specific affinity (binding property, affinity) with other molecules. Specific examples of the affinity tag include a histidine tag (His tag). The His tag is a short peptide with about 4 to 10 histidine residues, and has the property of binding specifically to metal ions such as nickel. Therefore, the isolation of modified fibroin by metal chelating chromatography (chelating metal chromatography) Can be used. Specific examples of the tag sequence include the amino acid sequence represented by SEQ ID NO: 11 (amino acid sequence including His tag sequence and hinge sequence).

Tag sequences such as glutathione-S-transferase (GST) that specifically binds to glutathione and maltose-binding protein (MBP) that specifically binds to maltose can also be used.

Furthermore, an “epitope tag” using an antigen-antibody reaction can also be used. By adding a peptide (epitope) exhibiting antigenicity as a tag sequence, an antibody against the epitope can be bound. As the epitope tag, HA (peptide sequence of hemagglutinin of influenza virus) tag, myc tag, FLAG tag and the like can be mentioned. By using the epitope tag, the modified fibroin can be easily purified with high specificity.

Furthermore, a tag sequence that can be separated with a specific protease can also be used. By treating the protein adsorbed via the tag sequence with protease, the modified fibroin from which the tag sequence has been separated can also be recovered.

As more specific examples of modified fibroin containing a tag sequence, (2-iii) the amino acid represented by SEQ ID NO: 12 (PRT380), SEQ ID NO: 13 (PRT410), SEQ ID NO: 14 (PRT525) or SEQ ID NO: 15 (PRT799) Examples include (2-iv) modified fibroin comprising an amino acid sequence having 90% or more sequence identity with the amino acid sequence shown in (2-iv) SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14 or SEQ ID NO: 15. .

The amino acid sequences represented by SEQ ID NO: 16 (PRT313), SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14 and SEQ ID NO: 15 are SEQ ID NO: 10, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8 and SEQ ID NO: 9, respectively. The amino acid sequence shown in SEQ ID NO: 11 (including His tag sequence and hinge sequence) is added to the N-terminus of the amino acid sequence shown.

(2-iii) The modified fibroin may be composed of the amino acid sequence represented by SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14 or SEQ ID NO: 15.

The modified fibroin (2-iv) includes an amino acid sequence having 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14 or SEQ ID NO: 15. The modified fibroin of (2-iv) is also a protein containing a domain sequence represented by Formula 1: [(A) _n motif-REP] _m . The sequence identity is preferably 95% or more.

The modified fibroin (2-iv) has an XGX (which has 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14 or SEQ ID NO: 15 and is contained in REP ( Where X is an amino acid residue other than glycine.) Z / w where z is the total number of amino acid residues of the amino acid sequence consisting of z and w is the total number of amino acid residues of REP in the domain sequence. Is preferably 50.9% or more.

The second modified fibroin may contain a secretion signal for releasing the protein produced in the recombinant protein production system to the outside of the host. The sequence of the secretion signal can be appropriately set according to the type of host.

The third modified fibroin has an amino acid sequence in which the domain sequence has a reduced content of (A) _n motif compared to naturally occurring fibroin. It can be said that the domain sequence of the third modified fibroin has an amino acid sequence corresponding to the deletion of at least one or more (A) _n motifs, as compared to naturally occurring fibroin.

The third modified fibroin may have an amino acid sequence corresponding to 10% to 40% deletion of the (A) _n motif from naturally occurring fibroin.

The third modification fibroin its domain sequence, compared to the naturally occurring fibroin, at least from the N-terminal side toward the C-terminal one to three (A) _n motif every one (A) _n motif May have an amino acid sequence corresponding to deletion of.

The third modified fibroin has a domain sequence that is at least two consecutive from the N-terminal side to the C-terminal side compared to the naturally occurring fibroin (A) deletion of the _n motif, and one (A ) It may have an amino acid sequence corresponding to the deletion of the _n motif repeated in this order.

The third modified fibroin may have an amino acid sequence whose domain sequence corresponds to that at least every two (A) _n motifs are deleted from the N-terminal side to the C-terminal side. .

The third modified fibroin includes a domain sequence represented by Formula 1: [(A) _n motif-REP] _m , and two adjacent [(A) _n motifs from the N-terminal side toward the C-terminal side. -REP] When the number of amino acid residues in the REP of the unit is sequentially compared, and the number of amino acid residues in the REP with a small number of amino acid residues is 1, the ratio of the number of amino acid residues in the other REP is 1.8 to When the maximum total value of the total number of amino acid residues of two adjacent [(A) _n motif-REP] units that becomes 11.3 is x and the total number of amino acid residues in the domain sequence is y In addition, it may have an amino acid sequence in which x / y is 20% or more, 30% or more, 40% or more, or 50% or more. (A) The number of alanine residues relative to the total number of amino acid residues in the _n motif may be 83% or more, preferably 86% or more, more preferably 90% or more, and 95% or more. More preferably, it is 100% (meaning that it is composed only of alanine residues).

The method for calculating x / y will be described in more detail with reference to FIG. FIG. 1 shows a domain sequence obtained by removing the N-terminal sequence and the C-terminal sequence from the modified fibroin. The domain sequence is from the N-terminal side (left side): (A) _n motif-first REP (50 amino acid residues)-(A) _n motif-second REP (100 amino acid residues)-(A) _n Motif-third REP (10 amino acid residues)-(A) _n motif-fourth REP (20 amino acid residues)-(A) _n motif-fifth REP (30 amino acid residues)-(A) _It has a sequence called _n motif.

Two adjacent [(A) _n motif-REP] units are sequentially selected from the N-terminal side to the C-terminal side so as not to overlap. At this time, an unselected [(A) _n motif-REP] unit may exist. FIG. 1 includes pattern 1 (comparison between the first REP and the second REP, and comparison between the third REP and the fourth REP), pattern 2 (comparison between the first REP and the second REP, and 4th REP and 5th REP), pattern 3 (2nd REP and 3rd REP comparison, 4th REP and 5th REP comparison), pattern 4 (first REP and Comparison of the second REP). There are other selection methods.

Next, for each pattern, the number of amino acid residues of each REP in the two adjacent [(A) _n motif-REP] units selected is compared. The comparison is performed by determining the ratio of the number of amino acid residues on the other side when the smaller number of amino acid residues is 1. For example, in the comparison of the first REP (50 amino acid residues) and the second REP (100 amino acid residues), when the first REP having a smaller number of amino acid residues is 1, the second REP The ratio of the number of amino acid residues is 100/50 = 2. Similarly, in the comparison of the fourth REP (20 amino acid residues) and the fifth REP (30 amino acid residues), when the fourth REP having a smaller number of amino acid residues is 1, the fifth REP The ratio of the number of amino acid residues is 30/20 = 1.5.

In FIG. 1, when the smaller number of amino acid residues is 1, the ratio of the number of other amino acid residues is 1.8 to 11.3 [(A) _n motif-REP] unit pairs Shown in solid line. In the present specification, this ratio is referred to as a jagged ratio. When the smaller number of amino acid residues is 1, the ratio of the number of other amino acid residues is less than 1.8 or more than 11.3. [(A) _n motif-REP] unit pairs are indicated by broken lines. Indicated.

In each pattern, the number of all amino acid residues of two adjacent [(A) _n motif-REP] units indicated by solid lines is added (not only REP but also (A) the number of amino acid residues of the _n motif. is there.). Then, the total value added is compared, and the total value (maximum value of the total value) of the pattern having the maximum total value is set as x. In the example shown in FIG. 1, the total value of pattern 1 is the maximum.

Next, x / y (%) can be calculated by dividing x by the total number of amino acid residues y of the domain sequence.

In the third modified fibroin, x / y is preferably 50% or more, more preferably 60% or more, still more preferably 65% or more, and even more preferably 70% or more. Preferably, it is still more preferably 75% or more, and particularly preferably 80% or more. There is no restriction | limiting in particular in the upper limit of x / y, For example, you may be 100% or less. When the jagged ratio is 1: 1.9 to 11.3, x / y is preferably 89.6% or more, and when the jagged ratio is 1: 1.8 to 3.4, x / y / Y is preferably 77.1% or more, and when the jagged ratio is 1: 1.9 to 8.4, x / y is preferably 75.9% or more, and the jagged ratio is 1 In the case of 1.9 to 4.1, x / y is preferably 64.2% or more.

A plurality of third modified fibroins are present in the domain sequence (A) When at least 7 of the _n motifs are modified fibroins composed of only alanine residues, x / y is 46.4% or more It is preferably 50% or more, more preferably 55% or more, still more preferably 60% or more, still more preferably 70% or more, and more preferably 80% or more. It is particularly preferred. There is no restriction | limiting in particular in the upper limit of x / y, and what is necessary is just 100% or less.

Here, x / y in naturally derived fibroin will be described. First, as described above, when a fibroin whose amino acid sequence information is registered in NCBI GenBank was confirmed by a method exemplified, 663 types of fibroin (of which 415 types were derived from spiders) were extracted. Of all the extracted fibroin, x / y is calculated from the amino acid sequence of naturally derived fibroin composed of the domain sequence represented by Formula 1: [(A) _n motif-REP] _m by the above-described calculation method. Was calculated. FIG. 3 shows the results when the jagged ratio is 1: 1.9 to 4.1.

3, the horizontal axis indicates x / y (%), and the vertical axis indicates frequency. As is clear from FIG. 3, x / y in naturally derived fibroin is less than 64.2% (the highest, 64.14%).

In the third modified fibroin, for example, one or a plurality of sequences encoding the _n motif is deleted so that x / y is 64.2% or more from the cloned gene sequence of naturally occurring fibroin. Can be obtained. In addition, for example, an amino acid sequence corresponding to the deletion of one or more (A) _n motifs is designed so that x / y is 64.2% or more from the amino acid sequence of naturally occurring fibroin. It can also be obtained by chemically synthesizing a nucleic acid encoding the amino acid sequence. In any case, in addition to the modification corresponding to the deletion of the (A) _n motif from the amino acid sequence of naturally occurring fibroin, one or more amino acid residues are further substituted, deleted, inserted and / or added. The amino acid sequence corresponding to this may be modified.

More specific examples of the third modified fibroin include (3-i) SEQ ID NO: 17 (Met-PRT399), SEQ ID NO: 7 (Met-PRT410), SEQ ID NO: 8 (Met-PRT525), or SEQ ID NO: 9 (Met -PRT799), or (3-ii) an amino acid sequence having 90% or more sequence identity with the amino acid sequence shown in SEQ ID NO: 17, SEQ ID NO: 7, SEQ ID NO: 8 or SEQ ID NO: 9, Mention may be made of modified fibroin.

The modified fibroin (3-i) will be described. The amino acid sequence represented by SEQ ID NO: 17 is derived from the amino acid sequence represented by SEQ ID NO: 10 (Met-PRT313) corresponding to naturally-occurring fibroin from the N-terminal side to the C-terminal side every two (A) _n The motif is deleted, and one [(A) _n motif-REP] is inserted before the C-terminal sequence. The amino acid sequence represented by SEQ ID NO: 7, SEQ ID NO: 8 or SEQ ID NO: 9 is as described in the second modified fibroin.

The value of x / y in the amino acid sequence represented by SEQ ID NO: 10 (corresponding to naturally-occurring fibroin) at a jagged ratio of 1: 1.8 to 11.3 is 15.0%. The value of x / y in the amino acid sequence shown by SEQ ID NO: 17 and the amino acid sequence shown by SEQ ID NO: 7 are both 93.4%. The value of x / y in the amino acid sequence represented by SEQ ID NO: 8 is 92.7%. The value of x / y in the amino acid sequence represented by SEQ ID NO: 9 is 89.8%. The z / w values in the amino acid sequences shown in SEQ ID NO: 10, SEQ ID NO: 17, SEQ ID NO: 7, SEQ ID NO: 8 and SEQ ID NO: 9 are 46.8%, 56.2%, 70.1% and 66. respectively. 1% and 70.0%.

The modified fibroin (3-i) may consist of the amino acid sequence represented by SEQ ID NO: 17, SEQ ID NO: 7, SEQ ID NO: 8 or SEQ ID NO: 9.

The modified fibroin (3-ii) includes an amino acid sequence having 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 17, SEQ ID NO: 7, SEQ ID NO: 8 or SEQ ID NO: 9. The modified fibroin of (3-ii) is also a protein containing a domain sequence represented by Formula 1: [(A) _n motif-REP] _m . The sequence identity is preferably 95% or more.

The modified fibroin of (3-ii) has 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 17, SEQ ID NO: 7, SEQ ID NO: 8 or SEQ ID NO: 9, and from the N-terminal side to the C-terminal side When the number of amino acid residues of REP of two adjacent [(A) _n motif-REP] units is sequentially compared, and the number of amino acid residues of REP having a small number of amino acid residues is 1, the other The amino acid residues of two adjacent [(A) _n motif-REP] units with a ratio of the number of amino acid residues of REP of 1.8 to 11.3 (giza ratio is 1: 1.8 to 11.3) It is preferable that x / y is 64.2% or more, where x is the maximum total value of the total number of bases and y is the total number of amino acid residues in the domain sequence.

The third modified fibroin may contain the tag sequence described above at one or both of the N-terminal and C-terminal.

As more specific examples of modified fibroin containing a tag sequence, (3-iii) amino acids represented by SEQ ID NO: 18 (PRT399), SEQ ID NO: 13 (PRT410), SEQ ID NO: 14 (PRT525) or SEQ ID NO: 15 (PRT799) And a modified fibroin comprising an amino acid sequence having 90% or more sequence identity with the sequence or (3-iv) the amino acid sequence shown in SEQ ID NO: 18, SEQ ID NO: 13, SEQ ID NO: 14 or SEQ ID NO: 15. .

The amino acid sequences represented by SEQ ID NO: 18, SEQ ID NO: 13, SEQ ID NO: 14 and SEQ ID NO: 15 are SEQ ID NO: 11 at the N-terminus of the amino acid sequences represented by SEQ ID NO: 17, SEQ ID NO: 7, SEQ ID NO: 8 and SEQ ID NO: 9, respectively. Are added to the amino acid sequence (including His tag sequence and hinge sequence).

(3-iii) The modified fibroin may be composed of the amino acid sequence represented by SEQ ID NO: 18, SEQ ID NO: 13, SEQ ID NO: 14 or SEQ ID NO: 15.

The modified fibroin (3-iv) comprises an amino acid sequence having 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 18, SEQ ID NO: 13, SEQ ID NO: 14 or SEQ ID NO: 15. The modified fibroin of (3-iv) is also a protein containing a domain sequence represented by Formula 1: [(A) _n motif-REP] _m . The sequence identity is preferably 95% or more.

The modified fibroin (3-iv) has a sequence identity of 90% or more with the amino acid sequence represented by SEQ ID NO: 18, SEQ ID NO: 13, SEQ ID NO: 14 or SEQ ID NO: 15, and from the N-terminal side to the C-terminal side. When the number of amino acid residues of REP of two adjacent [(A) _n motif-REP] units is sequentially compared, and the number of amino acid residues of REP having a small number of amino acid residues is 1, the other X is the maximum total value of the total number of amino acid residues of two adjacent [(A) _n motif-REP] units with a ratio of the number of amino acid residues of REP of 1.8 to 11.3. When the total number of amino acid residues of the domain sequence is y, x / y is preferably 64.2% or more.

The third modified fibroin may contain a secretion signal for releasing the protein produced in the recombinant protein production system to the outside of the host. The sequence of the secretion signal can be appropriately set according to the type of host.

The fourth modified fibroin has an amino acid sequence whose domain sequence has a reduced glycine residue content in addition to (A) a reduced content of the _n motif compared to naturally occurring fibroin. It is what you have. The domain sequence of the fourth modified fibroin has at least one or more (A) _n motifs deleted as compared to naturally occurring fibroin, and at least one or more glycine residues in the REP. It can be said to have an amino acid sequence corresponding to the substitution with another amino acid residue. That is, the fourth modified fibroin is a modified fibroin having the characteristics of the second modified fibroin described above and the third modified fibroin. Specific embodiments and the like are as described in the second modified fibroin and the third modified fibroin.

As more specific examples of the fourth modified fibroin, (4-i) SEQ ID NO: 7 (Met-PRT410), SEQ ID NO: 8 (Met-PRT525), SEQ ID NO: 9 (Met-PRT799), SEQ ID NO: 13 (PRT410) ), SEQ ID NO: 14 (PRT525) or SEQ ID NO: 15 (PRT799), or (4-ii) SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 13, SEQ ID NO: 14 or SEQ ID NO: 15 And a modified fibroin comprising an amino acid sequence having 90% or more sequence identity with the amino acid sequence represented by Specific embodiments of the modified fibroin comprising the amino acid sequence represented by SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 13, SEQ ID NO: 14 or SEQ ID NO: 15 are as described above.

The fifth modified fibroin has a domain sequence in which one or more amino acid residues in REP are replaced with amino acid residues having a higher hydrophobicity index and / or REP compared to naturally occurring fibroin. It may have an amino acid sequence including a region having a large hydrophobicity index corresponding to the insertion of one or more amino acid residues having a large hydrophobicity index.

The region where the hydrophobic index is locally large is preferably composed of 2 to 4 amino acid residues.

The amino acid residue having a large hydrophobicity index is an amino acid selected from isoleucine (I), valine (V), leucine (L), phenylalanine (F), cysteine (C), methionine (M) and alanine (A). More preferably, it is a residue.

The fifth modified fibroin has one or more amino acid residues in REP substituted with amino acid residues having a higher hydrophobicity index and / or one or more in REP compared to naturally occurring fibroin. In addition to the modification corresponding to the insertion of an amino acid residue having a large hydrophobicity index, further, substitution, deletion, insertion and / or addition of one or more amino acid residues as compared with naturally occurring fibroin There may be amino acid sequence modifications corresponding to the above.

For example, the fifth modified fibroin is obtained by removing one or more hydrophilic amino acid residues (for example, amino acid residues having a negative hydrophobicity index) in the REP from the cloned natural fibroin gene sequence. It can be obtained by substituting a group (for example, an amino acid residue having a positive hydrophobicity index) and / or inserting one or more hydrophobic amino acid residues in REP. In addition, for example, one or more hydrophilic amino acid residues in REP are substituted with hydrophobic amino acid residues from the amino acid sequence of naturally occurring fibroin, and / or one or more hydrophobic amino acid residues in REP It can also be obtained by designing an amino acid sequence corresponding to insertion of, and chemically synthesizing a nucleic acid encoding the designed amino acid sequence. In any case, one or more hydrophilic amino acid residues in REP have been replaced with hydrophobic amino acid residues from the amino acid sequence of naturally occurring fibroin and / or one or more hydrophobic amino acids in REP In addition to the modification corresponding to the insertion of a residue, the amino acid sequence corresponding to the substitution, deletion, insertion and / or addition of one or more amino acid residues may be further modified.

The fifth modified fibroin comprises a domain sequence represented by Formula 1: [(A) _n motif-REP] _m , and is located on the most C-terminal side (A) from the _n motif to the C terminus of the domain sequence. In all REPs included in the sequence excluding the sequence from the domain sequence, p is the total number of amino acid residues included in the region where the average value of the hydrophobicity index of four consecutive amino acid residues is 2.6 or more, (A) When the total number of amino acid residues contained in the sequence excluding the sequence from the _n motif to the C terminus of the domain sequence, which is located at the most C-terminal side, from the domain sequence is q, p / q is 6 It may have an amino acid sequence that is 2% or more.

As for the hydrophobicity index of amino acid residues, a known index (Hydropathy index: Kyte J, & Doolittle R (1982) “A simple method for displaying the hydropathic character of bio.p. 7”. 105-132). Specifically, the hydrophobicity index (hydropathic index, hereinafter also referred to as “HI”) of each amino acid is as shown in Table 1 below.

The method for calculating p / q will be described in more detail. For the calculation, a sequence obtained by removing the sequence from the domain sequence represented by Formula 1: [(A) _n motif-REP] _m to the most C-terminal side from the domain (A) _n motif to the C terminus of the domain sequence. (Hereinafter referred to as “array A”). First, in all REPs included in the sequence A, the average value of the hydrophobicity index of four consecutive amino acid residues is calculated. The average value of the hydrophobicity index is obtained by dividing the total HI of each amino acid residue contained in the four consecutive amino acid residues by 4 (number of amino acid residues). The average value of the hydrophobicity index is obtained for all four consecutive amino acid residues (each amino acid residue is used for calculating the average value 1 to 4 times). Next, a region where the average value of the hydrophobicity index of four consecutive amino acid residues is 2.6 or more is specified. Even if a certain amino acid residue corresponds to a plurality of “four consecutive amino acid residues whose average value of hydrophobicity index is 2.6 or more”, it should be included as one amino acid residue in the region. become. The total number of amino acid residues contained in the region is p. The total number of amino acid residues contained in sequence A is q.

For example, when 20 “four consecutive amino acid residues with an average value of hydrophobicity index of 2.6 or more” are extracted (no overlap), the average value of the hydrophobicity index of four consecutive amino acid residues is 2 The region of .6 or more contains 20 consecutive 4 amino acid residues (no overlap), and p is 20 × 4 = 80. In addition, for example, when two “four consecutive amino acid residues having an average value of hydrophobicity index of 2.6 or more” overlap by one amino acid residue, the hydrophobicity index of four consecutive amino acid residues In the region where the average value of is 2.6 or more, 7 amino acid residues are included (p = 2 × 4-1 = 7, where “−1” is a deduction of duplicates). For example, in the case of the domain sequence shown in FIG. 4, there are seven “4 consecutive amino acid residues with an average value of hydrophobicity index of 2.6 or more” without duplication, and therefore p is 7 × 4 = 28. For example, in the case of the domain sequence shown in FIG. 4, q is 4 + 50 + 4 + 40 + 4 + 10 + 4 + 20 + 4 + 30 = 170 (the (A) _n motif present at the end on the C-terminal side is not included). Next, p / q (%) can be calculated by dividing p by q. In the case of FIG. 4, 28/170 = 16.47%.

In the fifth modified fibroin, p / q is preferably 6.2% or more, more preferably 7% or more, further preferably 10% or more, and preferably 20% or more. Even more preferably, it is still more preferably 30% or more. The upper limit of p / q is not particularly limited, but may be 45% or less, for example.

The fifth modified fibroin is, for example, one or a plurality of hydrophilic amino acid residues (for example, a hydrophobicity index) in the REP so that the amino acid sequence of the naturally-derived fibroin thus cloned satisfies the above p / q condition. Is replaced with a hydrophobic amino acid residue (for example, an amino acid residue with a positive hydrophobicity index) and / or one or more hydrophobic amino acid residues are inserted in the REP By doing so, it can be obtained by locally modifying the amino acid sequence to include a region having a large hydrophobicity index. Alternatively, for example, an amino acid sequence satisfying the above p / q conditions can be designed from the amino acid sequence of naturally derived fibroin, and a nucleic acid encoding the designed amino acid sequence can be obtained by chemical synthesis. In any case, compared to naturally occurring fibroin, one or more amino acid residues in REP were replaced with amino acid residues having a higher hydrophobicity index and / or one or more amino acid residues in REP. In addition to modifications corresponding to insertion of amino acid residues having a large hydrophobicity index, modifications corresponding to substitution, deletion, insertion and / or addition of one or more amino acid residues may be performed. .

The amino acid residue having a large hydrophobicity index is not particularly limited, but isoleucine (I), valine (V), leucine (L), phenylalanine (F), cysteine (C), methionine (M) and alanine (A ) Are preferred, and valine (V), leucine (L) and isoleucine (I) are more preferred.

As a more specific example of the fifth modified fibroin, (5-i) the amino acid sequence represented by SEQ ID NO: 19 (Met-PRT720), SEQ ID NO: 20 (Met-PRT665) or SEQ ID NO: 21 (Met-PRT666), Or (5-ii) a modified fibroin comprising an amino acid sequence having 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 19, SEQ ID NO: 20 or SEQ ID NO: 21.

(5) The modified fibroin (5-i) will be described. The amino acid sequence represented by SEQ ID NO: 19 consists of 3 amino acid residues for every other REP with respect to the amino acid sequence represented by SEQ ID NO: 7 (Met-PRT410), excluding the domain sequence of the terminal on the C-terminal side. An amino acid sequence (VLI) is inserted at two positions, a part of glutamine (Q) residues is substituted with a serine (S) residue, and a part of amino acids on the C-terminal side is deleted. The amino acid sequence represented by SEQ ID NO: 20 is an amino acid sequence represented by SEQ ID NO: 8 (Met-PRT525) with one amino acid sequence (VLI) consisting of 3 amino acid residues inserted every other REP. is there. The amino acid sequence shown in SEQ ID NO: 21 is obtained by inserting two amino acid sequences (VLI) each consisting of 3 amino acid residues into the amino acid sequence shown in SEQ ID NO: 8 every other REP.

The modified fibroin (5-i) may be composed of the amino acid sequence represented by SEQ ID NO: 19, SEQ ID NO: 20 or SEQ ID NO: 21.

The modified fibroin (5-ii) comprises an amino acid sequence having 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 19, SEQ ID NO: 20 or SEQ ID NO: 21. The modified fibroin of (5-ii) is also a protein containing a domain sequence represented by Formula 1: [(A) _n motif-REP] _m . The sequence identity is preferably 95% or more.

The modified fibroin of (5-ii) has a sequence identity of 90% or more with the amino acid sequence represented by SEQ ID NO: 19, SEQ ID NO: 20 or SEQ ID NO: 21, and is located on the most C-terminal side (A) _n In all REPs included in the sequence excluding the sequence from the motif to the C-terminal of the domain sequence, the amino acids included in the region where the average value of the hydrophobicity index of 4 consecutive amino acid residues is 2.6 or more P is the total number of residues, and (A) When the total number of amino acid residues contained in the sequence excluding the sequence from the _n motif to the C terminus of the domain sequence from the domain sequence is q , P / q is preferably 6.2% or more.

The fifth modified fibroin may contain a tag sequence at one or both of the N-terminal and C-terminal.

More specific examples of the modified fibroin containing the tag sequence include (5-iii) the amino acid sequence represented by SEQ ID NO: 22 (PRT720), SEQ ID NO: 23 (PRT665) or SEQ ID NO: 24 (PRT666), or (5-iv And a modified fibroin comprising an amino acid sequence having 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 22, SEQ ID NO: 23 or SEQ ID NO: 24.

The amino acid sequences represented by SEQ ID NO: 22, SEQ ID NO: 23 and SEQ ID NO: 24 are the amino acid sequences represented by SEQ ID NO: 11 (His tag) at the N-terminus of the amino acid sequences represented by SEQ ID NO: 19, SEQ ID NO: 20 and SEQ ID NO: 21, respectively. Including a sequence and a hinge sequence).

(5-iii) The modified fibroin may be composed of the amino acid sequence represented by SEQ ID NO: 22, SEQ ID NO: 23, or SEQ ID NO: 24.

The modified fibroin (5-iv) comprises an amino acid sequence having 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 22, SEQ ID NO: 23 or SEQ ID NO: 24. The modified fibroin of (5-iv) is also a protein containing a domain sequence represented by Formula 1: [(A) _n motif-REP] _m . The sequence identity is preferably 95% or more.

The modified fibroin of (5-iv) has a sequence identity of 90% or more with the amino acid sequence represented by SEQ ID NO: 22, SEQ ID NO: 23 or SEQ ID NO: 24, and is located on the most C-terminal side (A) _n In all REPs included in the sequence excluding the sequence from the motif to the C-terminal of the domain sequence, the amino acids included in the region where the average value of the hydrophobicity index of 4 consecutive amino acid residues is 2.6 or more P is the total number of residues, and (A) When the total number of amino acid residues contained in the sequence excluding the sequence from the _n motif to the C terminus of the domain sequence from the domain sequence is q , P / q is preferably 6.2% or more.

The fifth modified fibroin may contain a secretion signal for releasing the protein produced in the recombinant protein production system to the outside of the host. The sequence of the secretion signal can be appropriately set according to the type of host.

The sixth modified fibroin has an amino acid sequence in which the content of glutamine residues is reduced compared to naturally occurring fibroin.

The sixth modified fibroin preferably contains at least one motif selected from GGX motif and GPGXX motif in the amino acid sequence of REP.

When the sixth modified fibroin contains a GPGXX motif in REP, the content ratio of the GPGXX motif is usually 1% or more, may be 5% or more, and is preferably 10% or more. There is no restriction | limiting in particular in the upper limit of GPGXX motif content rate, 50% or less may be sufficient and 30% or less may be sufficient.

In the present specification, the “GPGXX motif content” is a value calculated by the following method.
Formula 1: [(A) _n motif-REP] _m , or Formula 2: [(A) _n motif-REP] _m- (A) fibroin (modified fibroin or naturally derived) containing a domain sequence represented by the _n motif In fibroin), the number of GPGXX motifs contained in the region in all REPs contained in the sequence excluding the sequence from the domain sequence (A) _n motif located at the most C-terminal side to the C-terminus of the domain sequence. The number obtained by multiplying the total number by three (ie, corresponding to the total number of G and P in the GPGXX motif) is s, and is located at the most C-terminal side. (A) The sequence from the _n motif to the C-terminal of the domain sequence is determined from the domain sequence. (A) The content ratio of the GPGXX motif is calculated as s / t, where t is the total number of amino acid residues of all REPs excluding the _n motif. It is.

In the calculation of the content ratio of the GPGXX motif, “A sequence located at the most C-terminal side (A) excluding the sequence from the _n motif to the C-terminal of the domain sequence from the domain sequence” (A) The sequence from the _n motif to the C terminus of the domain sequence ”(sequence corresponding to REP) may include a sequence that is not highly correlated with the sequence characteristic of fibroin, and m is small In this case (that is, when the domain sequence is short), the calculation result of the content ratio of the GPGXX motif is affected, so this influence is excluded. When the “GPGXX motif” is located at the C-terminus of REP, even if “XX” is, for example, “AA”, it is treated as “GPGXX motif”.

FIG. 5 is a schematic diagram showing the domain sequence of the modified fibroin. The calculation method of the content ratio of GPGXX motif will be specifically described with reference to FIG. First, in the domain sequence of the modified fibroin shown in FIG. 5 (“[(A) _n motif-REP] _m- (A) _n motif” type), all REPs are “most C-terminally located”. (A) Since it is included in the “sequence excluding the sequence from the _n motif to the C terminal of the domain sequence from the domain sequence” (the sequence indicated by “region A” in FIG. 5), The number of GPGXX motifs is 7, and s is 7 × 3 = 21. Similarly, all REPs are “a sequence located at the most C-terminal side (A) The sequence from the _n motif to the C-terminal of the domain sequence is excluded from the domain sequence” (the sequence indicated by “region A” in FIG. )), The total number t of amino acid residues of all REPs excluding (A) the _n motif from the sequence is 50 + 40 + 10 + 20 + 30 = 150. Next, s / t (%) can be calculated by dividing s by t. In the case of the modified fibroin in FIG. 5, 21/150 = 14.0%.

The sixth modified fibroin preferably has a glutamine residue content of 9% or less, more preferably 7% or less, still more preferably 4% or less, and particularly preferably 0%. .

In the present specification, the “glutamine residue content” is a value calculated by the following method.
Formula 1: [(A) _n motif-REP] _m , or Formula 2: [(A) _n motif-REP] _m- (A) fibroin (modified fibroin or naturally derived) containing a domain sequence represented by the _n motif In fibroin), (A) the sequence from the _n- motif to the C-terminal of the domain sequence located on the most C-terminal side (sequence corresponding to “region A” in FIG. 5) is included. In the REP, the total number of glutamine residues contained in the region is u, the sequence from the (A) _n motif located at the most C-terminal side to the C-terminus of the domain sequence is excluded from the domain sequence, and (A) _n The glutamine residue content is calculated as u / t, where t is the total number of amino acid residues in all REPs excluding the motif. In the calculation of the glutamine residue content rate, the reason why "A sequence located at the most C-terminal side (A) excluding the sequence from the _n motif to the C-terminus of the domain sequence from the domain sequence" is the reason described above. It is the same.

The sixth modified fibroin corresponds to its domain sequence having one or more glutamine residues in REP deleted or replaced with other amino acid residues compared to naturally occurring fibroin. It may have an amino acid sequence.

The “other amino acid residue” may be an amino acid residue other than a glutamine residue, but is preferably an amino acid residue having a larger hydrophobicity index than the glutamine residue. Table 1 shows the hydrophobicity index of amino acid residues.

As shown in Table 1, amino acid residues having a larger hydrophobicity index than glutamine residues include isoleucine (I), valine (V), leucine (L), phenylalanine (F), cysteine (C), methionine (M ) Amino acid residues selected from alanine (A), glycine (G), threonine (T), serine (S), tryptophan (W), tyrosine (Y), proline (P) and histidine (H). it can. Among these, an amino acid residue selected from isoleucine (I), valine (V), leucine (L), phenylalanine (F), cysteine (C), methionine (M) and alanine (A) is more preferable. More preferably, it is an amino acid residue selected from isoleucine (I), valine (V), leucine (L) and phenylalanine (F).

In the sixth modified fibroin, the hydrophobicity of REP is preferably −0.8 or more, more preferably −0.7 or more, still more preferably 0 or more, and 0.3 or more. It is still more preferable that it is and it is especially preferable that it is 0.4 or more. There is no restriction | limiting in particular in the upper limit of the hydrophobicity of REP, It may be 1.0 or less and may be 0.7 or less.

In the present specification, the “hydrophobicity of REP” is a value calculated by the following method.
Formula 1: [(A) _n motif-REP] _m , or Formula 2: [(A) _n motif-REP] _m- (A) fibroin (modified fibroin or naturally derived) containing a domain sequence represented by the _n motif In fibroin), (A) the sequence from the _n- motif to the C-terminal of the domain sequence located on the most C-terminal side (sequence corresponding to “region A” in FIG. 5) is included. In the REP, the sum of the hydrophobicity index of each amino acid residue in the region is represented by v, and the sequence from the (A) _n motif located at the most C-terminal side to the C-terminus of the domain sequence is excluded from the domain sequence, and ( A) The hydrophobicity of REP is calculated as v / t, where t is the total number of amino acid residues of all REPs excluding the _n motif. In the calculation of the hydrophobicity of REP, the reason why “A sequence located at the most C-terminal side (A) excluding the sequence from the _n motif to the C-terminal of the domain sequence from the domain sequence” is the reason described above. It is the same.

The sixth modified fibroin has its domain sequence deleted one or more glutamine residues in REP and / or one or more glutamine residues in REP compared to naturally occurring fibroin. In addition to modifications corresponding to substitution of other amino acid residues, there may also be amino acid sequence modifications corresponding to substitution, deletion, insertion and / or addition of one or more amino acid residues. .

The sixth modified fibroin is, for example, deleting one or more glutamine residues in REP from the cloned gene sequence of naturally occurring fibroin and / or other one or more glutamine residues in REP. It can obtain by substituting to the amino acid residue. In addition, for example, one or more glutamine residues in REP are deleted from the amino acid sequence of naturally occurring fibroin, and / or one or more glutamine residues in REP are replaced with other amino acid residues. In particular, it can also be obtained by designing a corresponding amino acid sequence and chemically synthesizing a nucleic acid encoding the designed amino acid sequence.

More specific examples of the sixth modified fibroin include (6-i) SEQ ID NO: 25 (Met-PRT888), SEQ ID NO: 26 (Met-PRT965), SEQ ID NO: 27 (Met-PRT889), SEQ ID NO: 28 (Met -PRT916), a modified fibroin comprising the amino acid sequence shown in SEQ ID NO: 29 (Met-PRT918), SEQ ID NO: 30 (Met-PRT699), SEQ ID NO: 31 (Met-PRT698) or SEQ ID NO: 32 (Met-PRT966), or (6-ii) 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31 or SEQ ID NO: 32 Mention may be made of modified fibroin comprising an amino acid sequence having.

The (6-i) modified fibroin will be described. The amino acid sequence represented by SEQ ID NO: 25 is obtained by substituting VL for QQ in the amino acid sequence represented by SEQ ID NO: 7 (Met-PRT410). The amino acid sequence represented by SEQ ID NO: 26 is obtained by substituting all QQs in the amino acid sequence represented by SEQ ID NO: 7 with TS and replacing the remaining Q with A. The amino acid sequence represented by SEQ ID NO: 27 is obtained by substituting all QQs in the amino acid sequence represented by SEQ ID NO: 7 with VL and replacing the remaining Q with I. The amino acid sequence represented by SEQ ID NO: 28 is obtained by replacing all QQs in the amino acid sequence represented by SEQ ID NO: 7 with VI and replacing the remaining Q with L. The amino acid sequence represented by SEQ ID NO: 29 is one in which all QQs in the amino acid sequence represented by SEQ ID NO: 7 are substituted with VF, and the remaining Q is substituted with I.

The amino acid sequence represented by SEQ ID NO: 30 is obtained by substituting VL for all QQs in the amino acid sequence represented by SEQ ID NO: 8 (Met-PRT525). The amino acid sequence shown in SEQ ID NO: 31 is obtained by substituting all QQs in the amino acid sequence shown in SEQ ID NO: 8 with VL and replacing the remaining Q with I.

In the amino acid sequence represented by SEQ ID NO: 32, QQ in the sequence in which the region of 20 domain sequences present in the amino acid sequence represented by SEQ ID NO: 7 (Met-PRT410) is repeated twice is substituted with VF, And the remaining Q is replaced with I.

The amino acid sequences represented by SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31 and SEQ ID NO: 32 all have a glutamine residue content of 9% or less. Yes (Table 2).

The modified fibroin (6-i) comprises the amino acid sequence represented by SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31 or SEQ ID NO: 32. There may be.

The modified fibroin of (6-ii) is 90% or more of the amino acid sequence represented by SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31 or SEQ ID NO: 32 An amino acid sequence having the following sequence identity is included. The modified fibroin of (6-ii) is also represented by the formula 1: [(A) _n motif-REP] _m or the formula 2: [(A) _n motif-REP] _m- (A) _n motif. A protein containing a sequence. The sequence identity is preferably 95% or more.

The modified fibroin (6-ii) preferably has a glutamine residue content of 9% or less. The modified fibroin (6-ii) preferably has a GPGXX motif content of 10% or more.

The sixth modified fibroin may contain a tag sequence at one or both of the N-terminal and C-terminal. This makes it possible to isolate, immobilize, detect and visualize the modified fibroin.

As more specific examples of modified fibroin containing a tag sequence, (6-iii) SEQ ID NO: 33 (PRT888), SEQ ID NO: 34 (PRT965), SEQ ID NO: 35 (PRT889), SEQ ID NO: 36 (PRT916), SEQ ID NO: 37 (PRT918), SEQ ID NO: 38 (PRT699), SEQ ID NO: 39 (PRT698) or modified fibroin comprising the amino acid sequence shown by SEQ ID NO: 40 (PRT966), or (6-iv) SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, modified fibroin comprising an amino acid sequence having 90% or more sequence identity with the amino acid sequence represented by SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO: 38, SEQ ID NO: 39 or SEQ ID NO: 40.

The amino acid sequences represented by SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO: 38, SEQ ID NO: 39, and SEQ ID NO: 40 are SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, respectively. The amino acid sequence represented by SEQ ID NO: 11 (including His tag sequence and hinge sequence) was added to the N-terminus of the amino acid sequence represented by SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31 and SEQ ID NO: 32. Is. Since only the tag sequence was added to the N-terminus, there was no change in glutamine residue content, and SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO: 38, SEQ ID NO: 39. And the amino acid sequence represented by SEQ ID NO: 40 has a glutamine residue content of 9% or less (Table 3).

The modified fibroin (6-iii) comprises the amino acid sequence represented by SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO: 38, SEQ ID NO: 39, or SEQ ID NO: 40. There may be.

The modified fibroin of (6-iv) has 90% or more of the amino acid sequence represented by SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO: 38, SEQ ID NO: 39 or SEQ ID NO: 40 An amino acid sequence having the following sequence identity is included. The modified fibroin of (6-iv) is also a domain represented by Formula 1: [(A) _n motif-REP] _m or Formula 2: [(A) _n motif-REP] _m- (A) _n motif. A protein containing a sequence. The sequence identity is preferably 95% or more.

The modified fibroin (6-iv) preferably has a glutamine residue content of 9% or less. The modified fibroin (6-iv) preferably has a GPGXX motif content of 10% or more.

The sixth modified fibroin may contain a secretion signal for releasing the protein produced in the recombinant protein production system to the outside of the host. The sequence of the secretion signal can be appropriately set according to the type of host.

The modified fibroin has at least two or more of the characteristics of the first modified fibroin, the second modified fibroin, the third modified fibroin, the fourth modified fibroin, the fifth modified fibroin, and the sixth modified fibroin. It may be a modified fibroin having the following characteristics.

The limit oxygen index (LOI) value of the modified fibroin according to this embodiment may be 18 or more, 20 or more, 22 or more, 24 or more, 26 or more, 28 or more, 29 or more, or 30 or more. In this specification, the LOI value is a value measured in accordance with “Test method for powdered or low melting point synthetic resin” described in “Fire Safety No. 50 (May 31, 1995)”. is there.

The maximum hygroscopic exotherm calculated | required according to the following formula A of the modified fibroin which concerns on this embodiment may be more than 0.025 degreeC / g.
Formula A: Maximum moisture absorption exotherm = {(maximum value of sample temperature when the sample is placed in a low humidity environment until the sample temperature reaches equilibrium and then transferred to a high humidity environment) − (sample Sample temperature when placed in a low-humidity environment until the temperature reaches equilibrium and then moved to a high-humidity environment)} (° C.) / Sample weight (g)
In the formula A, a low humidity environment means an environment having a temperature of 20 ° C. and a relative humidity of 40%, and a high humidity environment means an environment having a temperature of 20 ° C. and a relative humidity of 90%.

The maximum moisture absorption exotherm of the modified fibroin according to this embodiment is 0.026 ° C./g or more, 0.027 ° C./g or more, 0.028 ° C./g or more, 0.029 ° C./g or more, 0.030 ° C. / G or more, 0.035 ° C./g or more, or 0.040 ° C./g or more. Although there is no restriction | limiting in particular in the upper limit of the maximum moisture absorption heat generation degree, Usually, it is 0.060 degrees C / g or less.

The modified fibroin according to the present embodiment may have a heat retention index determined according to the following formula B of 0.20 or more.
Formula B: Thermal insulation index = Heat retention ratio (%) / Sample weight (g / m ² )
Here, in this specification, the heat retention rate means a heat retention rate measured by a dry contact method using a Thermolab II type tester (under wind of 30 cm / second), and is measured by a method described in a reference example described later. Is the value to be

The heat retention index of the modified fibroin according to this embodiment may be 0.22 or more, may be 0.24 or more, may be 0.26 or more, may be 0.28 or more, and may be 0. .30 or more and 0.32 or more. Although there is no restriction | limiting in particular in the upper limit of a heat retention index | exponent, For example, it may be 0.60 or less or 0.40 or less.

<Method for producing modified fibroin>
The modified fibroin according to any of the above embodiments is, for example, a host transformed with an expression vector having a nucleic acid sequence encoding the modified fibroin and one or more regulatory sequences operably linked to the nucleic acid sequence. Can be produced by expressing the nucleic acid.

The method for producing the nucleic acid encoding the modified fibroin is not particularly limited. For example, using the gene encoding natural fibroin, the nucleic acid is produced by a method such as amplification by polymerase chain reaction (PCR), cloning, modification by genetic engineering techniques, or chemical synthesis. can do. The method for chemically synthesizing nucleic acids is not particularly limited. For example, based on the amino acid sequence information of fibroin obtained from the NCBI web database, etc., AKTA oligopilot plus 10/100 (GE Healthcare Japan Co., Ltd.) A gene can be chemically synthesized by a method of linking oligonucleotides that are synthesized automatically by PCR or the like. At this time, in order to facilitate purification and / or confirmation of the modified fibroin, a nucleic acid encoding the modified fibroin consisting of an amino acid sequence in which an amino acid sequence consisting of a start codon and a His10 tag is added to the N terminus of the above amino acid sequence is synthesized. May be.

Regulatory sequences are sequences that control the expression of modified fibroin in the host (for example, promoters, enhancers, ribosome binding sequences, transcription termination sequences, etc.), and can be appropriately selected depending on the type of host. As the promoter, an inducible promoter that functions in the host cell and can induce expression of the modified fibroin may be used. An inducible promoter is a promoter that can control transcription by the presence of an inducer (expression inducer), absence of a repressor molecule, or physical factors such as an increase or decrease in temperature, osmotic pressure or pH value.

The type of expression vector can be appropriately selected according to the type of host, such as a plasmid vector, virus vector, cosmid vector, fosmid vector, artificial chromosome vector, and the like. As the expression vector, a vector that can replicate autonomously in a host cell or can be integrated into a host chromosome and contains a promoter at a position where a nucleic acid encoding a modified fibroin can be transcribed is preferably used.

As the host, any of prokaryotes and eukaryotes such as yeast, filamentous fungi, insect cells, animal cells and plant cells can be preferably used.

Preferred examples of prokaryotic hosts include bacteria belonging to the genus Escherichia, Brevibacillus, Serratia, Bacillus, Microbacterium, Brevibacterium, Corynebacterium, Pseudomonas and the like. Examples of microorganisms belonging to the genus Escherichia include Escherichia coli. Examples of microorganisms belonging to the genus Brevibacillus include Brevibacillus agri and the like. Examples of microorganisms belonging to the genus Serratia include Serratia liqufaciens and the like. Examples of microorganisms belonging to the genus Bacillus include Bacillus subtilis. Examples of microorganisms belonging to the genus Microbacterium include microbacterium / ammonia film. Examples of microorganisms belonging to the genus Brevibacterium include Brevibacterium divaricatam. Examples of microorganisms belonging to the genus Corynebacterium include Corynebacterium ammoniagenes. Examples of microorganisms belonging to the genus Pseudomonas include Pseudomonas putida.

When a prokaryotic host is used, vectors for introducing a nucleic acid encoding a modified fibroin include, for example, pBTrp2 (manufactured by Boehringer Mannheim), pGEX (manufactured by Pharmacia), pUC18, pBluescriptII, pSupex, pET22b, pCold, pUB110, pNCO2 (Japanese Patent Laid-Open No. 2002-238696) and the like can be mentioned.

Examples of eukaryotic hosts include yeast and filamentous fungi (molds, etc.). Examples of the yeast include yeasts belonging to the genus Saccharomyces, Pichia, Schizosaccharomyces and the like. Examples of the filamentous fungi include filamentous fungi belonging to the genus Aspergillus, the genus Penicillium, the genus Trichoderma and the like.

When a eukaryote is used as a host, examples of a vector into which a nucleic acid encoding a modified fibroin is introduced include YEp13 (ATCC37115) and YEp24 (ATCC37051). As a method for introducing the expression vector into the host cell, any method can be used as long as it is a method for introducing DNA into the host cell. For example, a method using calcium ions [Proc. Natl. Acad. Sci. USA, 69, 2110 (1972)], electroporation method, spheroplast method, protoplast method, lithium acetate method, competent method, and the like.

As a method for expressing a nucleic acid by a host transformed with an expression vector, in addition to direct expression, secretory production, fusion protein expression, etc. can be performed according to the method described in Molecular Cloning 2nd edition, etc. .

The modified fibroin can be produced, for example, by culturing a host transformed with an expression vector in a culture medium, generating and accumulating the modified fibroin in the culture medium, and collecting from the culture medium. The method for culturing a host in a culture medium can be performed according to a method usually used for culturing a host.

When the host is a prokaryotic organism such as Escherichia coli or a eukaryotic organism such as yeast, the culture medium contains a carbon source, nitrogen source, inorganic salts, etc. that can be assimilated by the host, and can efficiently culture the host. If so, either a natural medium or a synthetic medium may be used.

Any carbon source may be used as long as it can be assimilated by the above-mentioned transformed microorganism. Examples thereof include glucose, fructose, sucrose, and carbohydrates such as molasses, starch and starch hydrolyzate, acetic acid and propionic acid, etc. Organic acids and alcohols such as ethanol and propanol can be used. Examples of the nitrogen source include ammonium salts of inorganic acids or organic acids such as ammonia, ammonium chloride, ammonium sulfate, ammonium acetate, and ammonium phosphate, other nitrogen-containing compounds, and peptone, meat extract, yeast extract, corn steep liquor, Casein hydrolyzate, soybean meal and soybean meal hydrolyzate, various fermented cells and digested products thereof can be used. As inorganic salts, for example, monopotassium phosphate, dipotassium phosphate, magnesium phosphate, magnesium sulfate, sodium chloride, ferrous sulfate, manganese sulfate, copper sulfate and calcium carbonate can be used.

Cultivation of prokaryotes such as E. coli or eukaryotes such as yeast can be performed under aerobic conditions such as shaking culture or deep aeration and agitation culture. The culture temperature is, for example, 15 to 40 ° C. The culture time is usually 16 hours to 7 days. The pH of the culture medium during the culture is preferably maintained at 3.0 to 9.0. The pH of the culture medium can be adjusted using an inorganic acid, an organic acid, an alkaline solution, urea, calcium carbonate, ammonia, or the like.

Moreover, during the culture, antibiotics such as ampicillin and tetracycline may be added to the culture medium as necessary. When culturing a microorganism transformed with an expression vector using an inducible promoter as a promoter, an inducer may be added to the medium as necessary. For example, isopropyl-β-D-thiogalactopyranoside is used when cultivating a microorganism transformed with an expression vector using the lac promoter, and indole acrylic is used when culturing a microorganism transformed with an expression vector using the trp promoter. An acid or the like may be added to the medium.

Isolation and purification of the expressed modified fibroin can be performed by a commonly used method. For example, when the modified fibroin is expressed in a dissolved state in the cells, the host cells are recovered by centrifugation after culturing, suspended in an aqueous buffer, and then subjected to an ultrasonic crusher, a French press, a manton. The host cells are disrupted with a Gaurin homogenizer, dynomill, etc. to obtain a cell-free extract. From the supernatant obtained by centrifuging the cell-free extract, a method usually used for protein isolation and purification, that is, a solvent extraction method, a salting-out method using ammonium sulfate, a desalting method, an organic solvent, etc. Precipitation method, anion exchange chromatography method using a resin such as diethylaminoethyl (DEAE) -Sepharose, DIAION HPA-75 (manufactured by Mitsubishi Kasei), and a positive using a resin such as S-Sepharose FF (manufactured by Pharmacia) Electrophoretic methods such as ion exchange chromatography, hydrophobic chromatography using resins such as butyl sepharose and phenyl sepharose, gel filtration using molecular sieve, affinity chromatography, chromatofocusing, isoelectric focusing Using methods such as these alone or in combination, purification It is possible to obtain the goods.

In addition, when the modified fibroin is expressed by forming an insoluble substance in the cell, the host cell is similarly collected, crushed, and centrifuged to collect the modified fibroin insoluble substance as a precipitate fraction. The recovered insoluble form of modified fibroin can be solubilized with a protein denaturant. After the operation, a purified preparation of modified fibroin can be obtained by the same isolation and purification method as described above. When the modified fibroin is secreted extracellularly, the modified fibroin can be recovered from the culture supernatant. That is, a culture supernatant is obtained by treating the culture with a technique such as centrifugation, and a purified preparation can be obtained from the culture supernatant by using the same isolation and purification method as described above.

<Artificial fibroin fiber>
The artificial fibroin fiber according to this embodiment is obtained by spinning the above-described modified fibroin and contains the above-described modified fibroin as a main component.

The artificial fibroin fiber according to this embodiment may have a LOI value of 18 or more, 20 or more, 22 or more, 24 or more, or 26 or more. 28 or more, 29 or more, or 30 or more.

The artificial fibroin fiber according to the present embodiment may have a maximum moisture absorption exotherm calculated according to the following formula A of more than 0.025 ° C./g.
Formula A: Maximum moisture absorption exotherm = {(maximum value of sample temperature when the sample is placed in a low humidity environment until the sample temperature reaches equilibrium and then transferred to a high humidity environment) − (sample Sample temperature when placed in a low-humidity environment until the temperature reaches equilibrium and then moved to a high-humidity environment)} (° C.) / Sample weight (g)
In the formula A, a low humidity environment means an environment having a temperature of 20 ° C. and a relative humidity of 40%, and a high humidity environment means an environment having a temperature of 20 ° C. and a relative humidity of 90%.

The artificial fibroin fiber according to this embodiment may have a maximum heat absorption exotherm of 0.026 ° C./g or more, 0.027 ° C./g or more, and 0.028 ° C./g or more. Or 0.029 ° C./g or more, 0.030 ° C./g or more, 0.035 ° C./g or more, or 0.040 ° C./g or more. It may be. Although there is no restriction | limiting in particular in the upper limit of the maximum moisture absorption heat generation degree, Usually, it is 0.060 degrees C / g or less.

The artificial fibroin fiber according to the present embodiment may have a heat retention index determined according to the following formula B of 0.20 or more.
Formula B: Thermal insulation index = Heat retention ratio (%) / Sample weight (g / m ² )

The heat retention index of the artificial fibroin fiber according to this embodiment may be 0.22 or more, may be 0.24 or more, may be 0.26 or more, may be 0.28 or more, It may be 0.30 or more, and may be 0.32 or more. Although there is no restriction | limiting in particular in the upper limit of a heat retention index | exponent, For example, it may be 0.60 or less or 0.40 or less.

<Manufacturing method of artificial fibroin fiber>
The artificial fibroin fiber according to the present embodiment can be produced by a known spinning method. That is, for example, when producing an artificial fibroin fiber containing a modified fibroin as a main component, first, the modified fibroin produced according to the above-described method is converted into dimethyl sulfoxide (DMSO), N, N-dimethylformamide (DMF), A dope solution is prepared by adding to a solvent such as formic acid or hexafluoroisopropanol (HFIP) together with an inorganic salt as a dissolution accelerator, if necessary, and dissolving. Next, the target artificial fibroin fiber can be obtained by spinning using this dope solution by a known spinning method such as wet spinning, dry spinning, dry wet spinning or melt spinning. Preferred spinning methods include wet spinning or dry wet spinning.

FIG. 6 is an explanatory view schematically showing an example of a spinning device for producing artificial fibroin fibers. A spinning device 10 illustrated in FIG. 6 is an example of a spinning device for dry and wet spinning, and includes an extrusion device 1, an undrawn yarn production device 2, a wet heat drawing device 3, and a drying device 4.

A spinning method using the spinning device 10 will be described. First, the dope solution 6 stored in the storage tank 7 is pushed out from the base 9 by the gear pump 8. In the lab scale, the dope solution may be filled into a cylinder and extruded from a nozzle using a syringe pump. Next, the extruded dope liquid 6 is supplied into the coagulating liquid 11 in the coagulating liquid tank 20 through the air gap 19, the solvent is removed, the modified fibroin is coagulated, and a fibrous coagulated body is formed. Next, the fibrous solidified body is supplied into the hot water 12 in the drawing bath 21 and drawn. The draw ratio is determined by the speed ratio between the supply nip roller 13 and the take-up nip roller 14. Thereafter, the stretched fibrous solidified body is supplied to the drying device 4 and dried in the yarn path 22, and an artificial fibroin fiber is obtained as the wound thread body 5. Reference numerals 18a to 18g denote thread guides.

The coagulation liquid 11 may be any solvent that can be desolvated, and examples thereof include lower alcohols having 1 to 5 carbon atoms such as methanol, ethanol and 2-propanol, and acetone. The coagulation liquid 11 may appropriately contain water. The temperature of the coagulation liquid 11 is preferably 0 to 30 ° C. When a syringe pump having a nozzle having a diameter of 0.1 to 0.6 mm is used as the base 9, the extrusion speed is preferably 0.2 to 6.0 ml / hour per hole, and 1.4 to 4.0 ml / hour More preferably it is time. The distance that the coagulated protein passes through the coagulation liquid 11 (substantially, the distance from the yarn guide 18a to the yarn guide 18b) may be a length that allows efficient desolvation, for example, 200 to 500 mm. It is. The take-up speed of the undrawn yarn may be, for example, 1 to 20 m / min, and preferably 1 to 3 m / min. The residence time in the coagulating liquid 11 may be, for example, 0.01 to 3 minutes, and preferably 0.05 to 0.15 minutes. Further, stretching (pre-stretching) may be performed in the coagulating liquid 11. The coagulating liquid tank 20 may be provided in multiple stages, and the stretching may be performed in each stage or a specific stage as necessary.

In addition, as the stretching performed when obtaining the artificial fibroin fiber, for example, dry stretching is also adopted in addition to the pre-stretching performed in the coagulating liquid tank 20 and the wet heat stretching performed in the stretching bath 21.

Wet heat stretching can be performed in warm water, in a solution obtained by adding an organic solvent or the like to warm water, or in steam heating. The temperature may be, for example, 50 to 90 ° C., and preferably 75 to 85 ° C. In wet heat drawing, undrawn yarn (or predrawn yarn) can be drawn, for example, 1 to 10 times, and preferably 2 to 8 times.

Dry heat stretching can be performed using an electric tubular furnace, a dry heat plate, or the like. The temperature may be, for example, 140 ° C. to 270 ° C., and preferably 160 ° C. to 230 ° C. In dry heat drawing, an undrawn yarn (or predrawn yarn) can be drawn, for example, 0.5 to 8 times, and preferably 1 to 4 times.

Wet heat stretching and dry heat stretching may be performed independently, or may be performed in multiple stages or in combination. That is, the first stage stretching is performed by wet heat stretching, the second stage stretching is performed by dry heat stretching, or the first stage stretching is performed by wet heat stretching, the second stage stretching is performed by wet heat stretching, and the third stage stretching is performed by dry heat stretching. For example, wet heat stretching and dry heat stretching can be appropriately combined.

The final draw ratio of the lower limit of the undrawn yarn (or predrawn yarn) is preferably more than 1 time, 2 times or more, 3 times or more, 4 times or more, 5 times or more, 6 times. Above, 7 times or more, 8 times or more, 9 times or more, and upper limit is preferably 40 times or less, 30 times or less, 20 times or less, 15 times or less, 14 times or less, 13 times or less 12 times or less, 11 times or less, and 10 times or less. When the artificial fibroin fiber is a fiber spun at a draw ratio of 2 times or more, the shrinkage rate when the artificial fibroin fiber is brought into a wet state by being brought into contact with water becomes higher.

<High shrinkage artificial fibroin fiber>
The high shrinkage artificial fibroin fiber according to the present embodiment is obtained by shrinking the above-described artificial fibroin fiber. The above-mentioned artificial fibroin fiber is sufficiently shrunk by being brought into a wet state by being brought into contact with water, and can be shrunk at a sufficiently high shrinkage rate under milder conditions than conventionally known synthetic fibers.

Therefore, in the high shrinkage artificial fibroin fiber according to the present embodiment, the shrinkage rate defined by the following formula is 2% or more.
Shrinkage rate = {1− (length of artificial fibroin fiber made wet by contact with water / length of artificial fibroin fiber after spinning and before contact with water)} × 100 (%)

The shrinkage rate of the high shrinkage artificial fibroin fiber according to the present embodiment is 2.5% or more, 3% or more, 3.5% or more, 4% or more, 4.5% or more, 5% or more, 5.5% or more. Or 6% or more. The upper limit of the shrinkage rate is not particularly limited, but 80% or less, 60% or less, 40% or less, 20% or less, 10% or less, 7% or less, 6% or less, 5% or less, 4% or less, or 3% or less It may be.

The high shrinkage artificial fibroin fiber according to this embodiment may have a LOI value of 18 or more, 20 or more, 22 or more, 24 or more, or 26 or more. It may be 28 or more, 29 or more, or 30 or more.

The high-shrinkage artificial fibroin fiber according to this embodiment may have a maximum moisture absorption exotherm calculated according to the following formula A of more than 0.025 ° C./g.
Formula A: Maximum moisture absorption exotherm = {(maximum value of sample temperature when the sample is placed in a low humidity environment until the sample temperature reaches equilibrium and then transferred to a high humidity environment) − (sample Sample temperature when placed in a low-humidity environment until the temperature reaches equilibrium and then moved to a high-humidity environment)} (° C.) / Sample weight (g)
In the formula A, a low humidity environment means an environment having a temperature of 20 ° C. and a relative humidity of 40%, and a high humidity environment means an environment having a temperature of 20 ° C. and a relative humidity of 90%.

The high-shrinkage artificial fibroin fiber according to this embodiment may have a maximum moisture absorption exotherm of 0.026 ° C./g or more, 0.027 ° C./g or more, or 0.028 ° C./g or more. May be 0.029 ° C / g or more, 0.030 ° C / g or more, 0.035 ° C / g or more, and 0.040 ° C / g. It may be g or more. Although there is no restriction | limiting in particular in the upper limit of the maximum moisture absorption heat generation degree, Usually, it is 0.060 degrees C / g or less.

The heat-shrinkability index calculated | required according to the following formula B may be 0.20 or more as for the high shrinkage artificial fibroin fiber which concerns on this embodiment.
Formula B: Thermal insulation index = Heat retention ratio (%) / Sample weight (g / m ² )

The heat retention index of the high shrinkage artificial fibroin fiber according to the present embodiment may be 0.22 or more, may be 0.24 or more, may be 0.26 or more, and may be 0.28 or more. It may be 0.30 or more and may be 0.32 or more. Although there is no restriction | limiting in particular in the upper limit of a heat retention index | exponent, For example, it may be 0.60 or less or 0.40 or less.

<Method for producing high shrinkage artificial fibroin fiber>
The method for producing high-shrinkage artificial fibroin fibers according to the present embodiment includes a step (hereinafter, also referred to as “shrinking step”) in which the artificial fibroin fibers containing the modified fibroin are brought into contact with water having a boiling point below.

In the shrinking step, the artificial fibroin fiber is brought into a wet state by bringing the artificial fibroin fiber into contact with water having a boiling point (hereinafter also referred to as “contact step”). The wet state means a state in which at least a part of the artificial fibroin fiber is wet with water. Thereby, an artificial fibroin fiber can be shrunk | reduced irrespective of external force, and a highly shrinkable artificial fibroin fiber can be obtained. It is considered that the contraction of the artificial fibroin fiber in the contacting step due to the external force is caused by the following reason, for example. That is, one reason is considered to be due to the secondary structure or tertiary structure of the artificial fibroin, and another reason is that, for example, in the artificial fibroin fiber having a residual stress due to stretching in the manufacturing process, water is It is considered that the residual stress is relaxed by entering between the fibers or in the fibers. Therefore, it is considered that the shrinkage ratio of the artificial fibroin fiber in the shrinking process can be arbitrarily controlled according to the size of the draw ratio in the manufacturing process of the artificial fibroin fiber described above, for example.

The temperature of the water contacted with the artificial fibroin fiber in the contact step may be less than the boiling point. Thereby, the handleability and the workability of the shrinking process are improved. Further, from the viewpoint of sufficiently shortening the shrinkage time, the lower limit value of the water temperature is preferably 10 ° C or higher, more preferably 40 ° C or higher, and further preferably 70 ° C or higher. . The upper limit of the water temperature is preferably 90 ° C. or lower.

In the contacting step, the method for bringing water into contact with the artificial fibroin fiber is not particularly limited. Examples of the method include, for example, a method of immersing the artificial fibroin fiber in water, a method of spraying water on the artificial fibroin fiber at room temperature or in a heated steam state, and the high humidity where the artificial fibroin fiber is filled with water vapor. Examples include exposure to the environment. Among these methods, the method of immersing artificial fibroin fiber in water is preferable in the contact step because the shrinkage time can be effectively shortened and the processing equipment can be simplified.

In the contact step, when the artificial fibroin fiber is brought into contact with water in a relaxed state, the artificial fibroin fiber may not only contract but also shrink like a wave. In order to prevent the occurrence of such shrinkage, for example, the contact step is performed in a state where the artificial fibroin fiber is not relaxed, for example, the artificial fibroin fiber is brought into contact with water below the boiling point while being tensioned (pulled) in the fiber axis direction. May be.

After the shrinking step, the wet highly shrinkable artificial fibroin fiber may be dried (hereinafter also referred to as “drying step”).

The drying step is a step of drying the high shrinkage artificial fibroin fiber that has undergone the shrinkage step. Drying may be, for example, natural drying or forced drying using a drying facility. As the drying equipment, any known drying equipment of contact type or non-contact type can be used. The drying temperature is not limited as long as it is lower than the temperature at which, for example, the protein contained in the high-shrinkage artificial fibroin fiber is decomposed or the high-shrinkage artificial fibroin fiber is thermally damaged. However, in general, the temperature is in the range of 20 to 150 ° C., and the temperature is preferably in the range of 50 to 100 ° C. The temperature in this range allows the high shrinkage artificial fibroin fiber to dry more quickly and efficiently without thermal damage of the high shrinkage artificial fibroin fiber or degradation of the protein contained in the high shrinkage artificial fibroin fiber. Is done. The drying time is appropriately set according to the drying temperature or the like, and for example, a time that can eliminate as much as possible the influence on the quality and physical properties of the high shrinkage artificial fibroin fiber due to overdrying is adopted.

In the method for producing a high-shrinkage artificial fibroin fiber according to the present embodiment, a high-shrinkage artificial fibroin fiber having a shrinkage rate of 2% or more can be obtained through the shrinking step.

FIG. 7 is an explanatory view schematically showing an example of a production apparatus for producing high-shrinkage artificial fibroin fibers. The manufacturing apparatus 40 shown in FIG. 7 includes a feed roller 42 that feeds out artificial fibroin fibers, a winder 44 that winds up the highly shrinkable artificial fibroin fibers 38, a water bath 46 that performs a shrinking process, and a dryer 48 that performs a drying process. And is configured.

More specifically, the feed roller 42 can be attached with a wound product of the artificial fibroin fiber 36, and the artificial fibroin fiber 36 is continuously formed from the wound product of the artificial fibroin fiber 36 by rotation of an electric motor (not shown). Can be delivered automatically and automatically. The winder 44 continuously and automatically turns the artificial fibroin fiber 36 (high-shrinking artificial fibroin fiber 38), which is fed from the feed roller 42 and then contracted through the contact step and the drying step, by the rotation of an electric motor (not shown). It can be wound up. Here, the feeding speed of the artificial fibroin fiber 36 by the feed roller 42 and the winding speed of the highly shrinkable artificial fibroin fiber 38 by the winder 44 can be controlled independently of each other.

The water bath 46 and the dryer 48 are arranged side by side between the feed roller 42 and the winder 44 on the upstream side and the downstream side in the feeding direction of the artificial fibroin fiber 36. 7 includes

relay rollers

50 and 52 that relay the artificial fibroin fiber 36 before and after contraction, which travels from the feed roller 42 toward the winder 44.

The water bath 46 has a heater 54, and hot water 47 heated by the heater 54 is accommodated in the water bath 46. A tension roller 56 is installed in the water bath 46 so as to be immersed in the hot water 47. As a result, the artificial fibroin fiber 36 fed out from the feed roller 42 travels toward the winder 44 while being immersed in the hot water 47 while being wound around the tension roller 56 in the water bath 46. It has become. The immersion time of the artificial fibroin fiber 36 in the hot water 47 is appropriately controlled according to the traveling speed of the artificial fibroin fiber 36.

The dryer 48 has a pair of hot rollers 58. The pair of hot rollers 58 can be wound around the artificial fibroin fiber 36 that moves away from the water bath 46 and travels toward the winder 44 side. As a result, the artificial fibroin fiber 36 immersed in the hot water 47 in the water bath 46 is heated by the pair of hot rollers 58 in the dryer 48 and dried, and then sent out further toward the winder 44. It has become.

When manufacturing the high shrinkage artificial fibroin fiber 38 using the manufacturing apparatus 40 having such a structure, first, for example, the artificial fibroin fiber 36 spun using the spinning apparatus 10 shown in FIG. 6 is used. The wound material is attached to the feed roller 42. Next, the artificial fibroin fiber 36 is continuously fed from the feed roller 42 and immersed in hot water 47 in the water bath 46. At this time, for example, the winding speed of the winder 44 is set slower than the feeding speed of the feed roller 42. Thereby, since the artificial fibroin fiber 36 is contracted by contact with the hot water 47 in a state where the artificial fibroin fiber 36 is tensioned so as not to relax between the feed roller 42 and the winder 44, occurrence of crimping can be prevented. By contact with hot water 47, the artificial fibroin fiber 36 contracts, and a highly contracted artificial fibroin fiber 38 is obtained.

Next, the high shrinkage artificial fibroin fiber 38 is heated by the pair of hot rollers 58 of the dryer 48. Thereby, the high shrinkage artificial fibroin fiber 38 can be dried. At this time, by controlling the ratio between the feed speed of the feed roller 42 and the winding speed of the winder 44, the high-shrinkage artificial fibroin fiber 38 can be further shrunk, and the length can be kept unchanged. The obtained high-shrinkage artificial fibroin fiber 38 is wound up by a winder 44 to obtain a wound product of the high-shrinkage artificial fibroin fiber 38.

Note that, instead of the pair of hot rollers 58, the high-shrinkage artificial fibroin fiber 38 may be dried using a drying facility consisting of only a heat source such as a dry heat plate 64 as shown in FIG. Also in this case, by adjusting the relative speed of the feed speed of the feed roller 42 and the winding speed of the winder 44 in the same manner as in the case of using a pair of hot rollers 58 as a drying facility, a high shrinkage artificial structure is achieved. The fibroin fiber 38 can be further shrunk or the length can be kept unchanged. Here, the drying means is constituted by the dry heat plate 64. Further, the dryer 48 is not essential.

As described above, by using the manufacturing apparatus 40, the target high-shrinkage artificial fibroin fiber 38 can be manufactured automatically, continuously, and extremely easily.

FIG. 8 is an explanatory view schematically showing another example of a production apparatus for producing high-shrinkage artificial fibroin fibers. FIG. 8A shows a processing apparatus that performs the shrinking process included in the manufacturing apparatus, and FIG. 8B shows a drying apparatus that performs the drying process included in the manufacturing apparatus. The manufacturing apparatus shown in FIG. 8 has a processing device 60 that performs a shrinking process on the artificial fibroin fiber 36 and a drying device 62 that dries the resulting high-shrinkage artificial fibroin fiber 38, and these are independent of each other. It is said that.

More specifically, the processing device 60 shown in FIG. 8A omits the dryer 48 from the manufacturing device 40 shown in FIG. 7 and replaces the feed roller 42, the water bath 46, and the winder 44 with an artificial. It has a structure in which the fibroin fibers 36 are arranged in order from the upstream side to the downstream side in the traveling direction. In such a processing device 60, the artificial fibroin fiber 36 fed from the feed roller 42 is immersed in hot water 47 in the water bath 46 and contracted. The high-shrinkage artificial fibroin fiber 38 obtained by shrinkage is wound up by a winder 44.

8B includes a feed roller 42 and a winder 44, and a dry heat plate 64. The dry heat plate 64 is disposed between the feed roller 42 and the winder 44 so that the dry heat surface 66 is in contact with the high-shrinkage artificial fibroin fiber 38 and extends in the running direction. In the drying device 62, as described above, the high-shrinkage artificial fibroin fiber 38 can be further shrunk by controlling the ratio of the feed speed of the feed roller 42 and the wind-up speed of the winder 44, for example. , You can not change the length.

By using the manufacturing apparatus having such a structure, the artificial fibroin fiber 36 is contracted by the processing apparatus 60 to obtain the desired high-shrinking artificial fibroin fiber 38, and then the high-shrinking artificial fibroin fiber 38 is obtained by the drying apparatus 62. Can be dried.

Note that the processing apparatus 60 may be configured with only the water bath 46 by omitting the feed roller 42 and the winder 44 from the processing apparatus 60 shown in FIG. In the case of using a manufacturing apparatus having such a processing apparatus, for example, high-shrinkage artificial fibroin fibers are manufactured in a so-called batch type. Moreover, the drying apparatus 62 shown in FIG.8 (b) is not essential.

<Use of high shrinkage artificial fibroin fiber>
Since the high-shrinkage artificial fibroin fiber according to the present invention is shrunk at a high shrinkage rate, it is excellent in touch and flexibility, and is suitable as a fiber used for, for example, clothing and bedding.

[Shrinking method of artificial fibroin fiber]
The manufacturing method of the high shrinkage artificial fibroin fiber of the present invention described above includes a step of shrinking an artificial fibroin fiber containing modified fibroin by bringing it into contact with water having a boiling point below, and the shrinkage rate defined by the following formula is 2 %, It can also be regarded as a shrinkage method of artificial fibroin fiber.
Shrinkage rate = {1− (length of artificial fibroin fiber made wet by contact with water / length of artificial fibroin fiber after spinning and before contact with water)} × 100 (%)

Hereinafter, the present invention will be described more specifically based on examples and the like. However, the present invention is not limited to the following examples.

[Test Example 1: Evaluation of high shrinkage artificial fibroin fiber]
(1) Production of modified fibroin (artificial fibroin) (synthesis of nucleic acid encoding modified fibroin and construction of expression vector)
Modified fibroin having the amino acid sequence represented by SEQ ID NO: 18 (PRT399), modified fibroin having the amino acid sequence represented by SEQ ID NO: 12 (PRT380), modified fibroin having the amino acid sequence represented by SEQ ID NO: 13 (PRT410), and sequence A modified fibroin (PRT799) having the amino acid sequence shown by number 15 was designed.

The nucleic acids encoding the four types of designed modified fibroin were synthesized respectively. The nucleic acid was added with an NdeI site at the 5 'end and an EcoRI site downstream of the stop codon. These four types of nucleic acids were cloned into a cloning vector (pUC118). Thereafter, the nucleic acid was cleaved by restriction enzyme treatment with NdeI and EcoRI, and then recombined with the protein expression vector pET-22b (+) to obtain an expression vector.

(Expression of modified fibroin)
Escherichia coli BLR (DE3) was transformed with the obtained pET-22b (+) expression vector. The transformed Escherichia coli was cultured in 2 mL of LB medium containing ampicillin for 15 hours. The culture solution was added to 100 mL of a seed culture medium (Table 4) containing ampicillin so that the OD ₆₀₀ was 0.005. The culture temperature was kept at 30 ° C., and flask culture was performed until the OD ₆₀₀ reached 5 (about 15 hours) to obtain a seed culture solution.

The seed culture was added to a jar fermenter to which 500 mL of production medium (Table 5) was added so that the OD ₆₀₀ was 0.05. The culture solution temperature was maintained at 37 ° C., and the culture was performed at a constant pH of 6.9. The dissolved oxygen concentration in the culture solution was maintained at 20% of the dissolved oxygen saturation concentration.

Immediately after the glucose in the production medium was completely consumed, a feed solution (glucose 455 g / 1 L, Yeast Extract 120 g / 1 L) was added at a rate of 1 mL / min. The culture solution temperature was maintained at 37 ° C., and the culture was performed at a constant pH of 6.9. The culture was performed for 20 hours while maintaining the dissolved oxygen concentration in the culture solution at 20% of the dissolved oxygen saturation concentration. Thereafter, 1M isopropyl-β-thiogalactopyranoside (IPTG) was added to the culture solution to a final concentration of 1 mM to induce expression of the target modified fibroin. At the time when 20 hours passed after the addition of IPTG, the culture solution was centrifuged, and the cells were collected. SDS-PAGE was performed using cells prepared from the culture solution before and after IPTG addition, and the appearance of a band corresponding to the size of the target modified fibroin depending on the addition of IPTG Expression was confirmed.

(Purification of modified fibroin)
The cells recovered 2 hours after the addition of IPTG were washed with 20 mM Tris-HCl buffer (pH 7.4). The washed cells were suspended in 20 mM Tris-HCl buffer (pH 7.4) containing about 1 mM PMSF, and the cells were disrupted with a high-pressure homogenizer (GEA Niro Soavi). The disrupted cells were centrifuged to obtain a precipitate. The resulting precipitate was washed with 20 mM Tris-HCl buffer (pH 7.4) until high purity. The washed precipitate was suspended in 8M guanidine buffer (8M guanidine hydrochloride, 10 mM sodium dihydrogen phosphate, 20 mM NaCl, 1 mM Tris-HCl, pH 7.0) to a concentration of 100 mg / mL, and 60 ° C. And stirred for 30 minutes with a stirrer to dissolve. After dissolution, dialysis was performed with water using a dialysis tube (cellulose tube 36/32 manufactured by Sanko Junyaku Co., Ltd.). White aggregated protein obtained after dialysis was collected by centrifugation. Water was removed from the recovered aggregated protein with a freeze dryer to obtain the desired modified fibroin freeze-dried powder.

(2) Manufacture of artificial fibroin fiber (preparation of dope solution)
Prepare dimethyl sulfoxide (DMSO) in which LiCl is dissolved to 4.0% by mass as a solvent, and add a lyophilized powder of modified fibroin to the concentration of 18% by mass or 24% by mass (Table). 6) and dissolved for 3 hours using a shaker. Thereafter, insoluble matters and bubbles were removed to obtain a modified fibroin solution.

(spinning)
Using the obtained modified fibroin solution as a dope solution (spinning stock solution), spun and drawn artificial fibroin fibers were produced by dry and wet spinning using a spinning device similar to the spinning device 10 shown in FIG. The spinning device used is a spinning device 10 shown in FIG. 6, and a second undrawn yarn production device (a first bath) and a wet heat drawing device 3 (third bath) are further provided between the undrawn yarn production device 2 (first bath) and the wet heat drawing device 3 (third bath). A second bath). The dry and wet spinning conditions are as follows.
Extrusion nozzle diameter: 0.2 mm
Liquid and temperature in the first to third baths: see Table 6 Total draw ratio: see Table 6 Drying temperature: 60 ° C.

(3) Manufacture and evaluation of high shrinkage artificial fibroin fiber (shrinkage process)
A high-shrinkage artificial fibroin fiber was produced by subjecting each of the artificial fibroin fibers obtained in Production Examples 1 to 19 to contact with water having a boiling point below.

A plurality of artificial fibroin fibers each having a length of 30 cm were cut out from the wound product of artificial fibroin fibers obtained in Production Examples 1 to 19. The plurality of artificial fibroin fibers were bundled to obtain an artificial fibroin fiber bundle having a fineness of 150 denier. A 0.8 g lead weight was attached to each artificial fibroin fiber bundle, and in this state, each artificial fibroin fiber bundle was immersed in water at a temperature shown in Tables 7 to 10 for 10 minutes (contact step). Thereafter, the length of each artificial fibroin fiber bundle was measured in water. The measurement of the length of the artificial fibroin fiber bundle in water was carried out with a 0.8 g lead weight attached to the artificial fibroin fiber bundle in order to eliminate the shrinkage of the artificial fibroin fiber bundle. Next, the shrinkage rate (%) of each artificial fibroin fiber was calculated according to the following formula I. In Formula I, L0 represents the length of the artificial fibroin fiber bundle (here 30 cm) after spinning and before contact with water, and Lw represents the length of the contracted artificial fibroin fiber bundle.
Formula I: Shrinkage rate = {1− (Lw / L0)} × 100 (%)

The results are shown in Tables 7-10.

The high-shrinkage artificial fibroin fiber of the present invention had a sufficiently high shrinkage rate and was excellent in touch and flexibility. In addition, since it can manufacture by the contact step made to contact with water below boiling point, it can manufacture safely.

[Reference Example 1: Evaluation of flame retardancy of modified fibroin]
In the same manner as in Test Example 1, a freeze-dried powder of modified fibroin (PRT799) was obtained. PRT799 is a hydrophilic modified fibroin with an average HI of 0 or less.

A modified fibroin (PRT799) freeze-dried powder was added to a LiCl solution in DMSO (concentration: 4.0% by mass) to a concentration of 24% by mass, and dissolved by mixing for 3 hours using a shaker. It was. Thereafter, insoluble matters and bubbles were removed to obtain a modified fibroin solution (spinning stock solution).

The spinning dope is filtered through a metal filter with an opening of 5 μm at 90 ° C., then left to stand in a 30 mL stainless syringe and defoamed, and then in a 100 mass% methanol coagulation bath from a solid nozzle with a needle diameter of 0.2 mm. Was discharged. The discharge temperature was 90 ° C. After coagulation, the obtained raw yarn was wound up and naturally dried to obtain modified fibroin fiber (raw fiber).

A knitted fabric (thickness: 180 denier, number of gauges: 18) was manufactured by circular knitting using a circular knitting machine using twisted yarns obtained by twisting raw material fibers. 20 g of the obtained knitted fabric was cut out and used as a test piece.

The flammability test was conducted in accordance with “Test method for powdered or low melting point synthetic resin” described in “Fire Safety No. 50 (May 31, 1995)”. The test was performed under conditions of a temperature of 22 ° C., a relative humidity of 45%, and an atmospheric pressure of 1021 hPa. Table 11 shows the measurement results (oxygen concentration (%), combustion rate (%), and converted combustion rate (%)).

As a result of the flammability test, the critical oxygen index (LOI) value of the knitted fabric knitted with the modified fibroin (PRT799) fiber was 27.2. Generally, if the LOI value is 26 or more, it is considered to be flame retardant. It can be seen that the modified fibroin is excellent in flame retardancy.

[Reference Example 2: Evaluation of hygroscopic exothermic property of modified fibroin]
In the same manner as in Test Example 1, lyophilized powders of modified fibroin (PRT918 and PRT799) were obtained. PRT918 is a hydrophobically modified fibroin having the amino acid sequence set forth in SEQ ID NO: 37 and having an average HI greater than zero.

By adding a lyophilized powder of modified fibroin (PRT918 and PRT799) to a LiCl solution in DMSO (concentration: 4.0% by mass) to a concentration of 24% by mass and mixing for 3 hours using a shaker, Dissolved. Thereafter, insoluble matters and bubbles were removed to obtain a modified fibroin solution (spinning stock solution).

The spinning dope is filtered through a metal filter having a mesh size of 5 μm at 60 ° C., then left to stand in a 30 mL stainless syringe and defoamed, and then in a 100 mass% methanol coagulation bath from a solid nozzle having a needle diameter of 0.2 mm. Was discharged. The discharge temperature was 60 ° C. After coagulation, the obtained raw yarn was wound up and naturally dried to obtain modified fibroin fiber (raw fiber).

For comparison, commercially available wool fibers, cotton fibers, tencel fibers, rayon fibers and polyester fibers were prepared as raw fibers.

Each raw material fiber was used to produce knitted fabrics by flat knitting using a flat knitting machine. Table 12 shows the thickness and gauge number of the knitted fabric using PRT918 fiber or PRT799 fiber. The thickness and the number of gauges of the knitted fabric using other raw material fibers were adjusted so that the cover factor was almost the same as the cover factor of the knitted fabric of the modified fibroin fiber. Specifically, it is as shown in Table 12.

2 pieces of knitted fabric cut to 10 cm × 10 cm were put together, and four sides were sewn together to obtain a test piece (sample). After leaving the test piece in a low humidity environment (temperature 20 ± 2 ° C., relative humidity 40 ± 5%) for 4 hours or more, it is transferred to a high humidity environment (temperature 20 ± 2 ° C., relative humidity 90 ± 5%). The temperature was measured at intervals of 1 minute by a temperature sensor attached to the center of the interior for 30 minutes.

From the measurement results, the maximum moisture absorption exotherm was determined according to the following formula A.
Formula A: Maximum moisture absorption exotherm = {(maximum value of sample temperature when the sample is placed in a low humidity environment until the sample temperature reaches equilibrium and then transferred to a high humidity environment) − (sample Sample temperature when placed in a low-humidity environment until the temperature reaches equilibrium and then moved to a high-humidity environment)} (° C.) / Sample weight (g)

FIG. 9 is a graph showing an example of the results of the hygroscopic exothermic test. The horizontal axis of the graph represents the time (minutes) left in the high humidity environment, with the time when the sample was transferred from the low humidity environment to the high humidity environment as 0. The vertical axis of the graph indicates the temperature (sample temperature) measured by the temperature sensor. In the graph shown in FIG. 9, the point indicated by M corresponds to the maximum value of the sample temperature.

Table 13 shows the calculation results of the maximum moisture absorption exotherm.

As shown in Table 13, it can be seen that the modified fibroin (PRT918 and PRT799) fibers have a higher maximum heat absorption exotherm and superior hygroscopic heat generation compared to existing materials.

[Reference Example 3: Evaluation of heat retention of modified fibroin]
In the same manner as in Test Example 1, lyophilized powders of modified fibroin (PRT966 and PRT799) were obtained. PRT966 is a hydrophobically modified fibroin having the amino acid sequence set forth in SEQ ID NO: 40 and having an average HI greater than zero.

By adding a lyophilized powder of modified fibroin (PRT966 and PRT799) to a LiCl solution in DMSO (concentration: 4.0% by mass) to a concentration of 24% by mass, and mixing for 3 hours using a shaker, Dissolved. Thereafter, insoluble matters and bubbles were removed to obtain a modified fibroin solution (spinning stock solution).

For comparison, commercially available wool fibers, silk fibers, cotton fibers, rayon fibers and polyester fibers were prepared as raw fibers.

Each raw material fiber was used to produce knitted fabrics by flat knitting using a flat knitting machine. Table 14 shows the count, the number of twists, the number of gauges, and the basis weight of the knitted fabric using PRT966 fiber and PRT799 fiber. The thickness and the number of gauges of the knitted fabric using other raw material fibers were adjusted so that the cover factor was almost the same as the cover factor of the knitted fabric of the modified fibroin fiber. Specifically, it is as shown in Table 14.

Thermal insulation was evaluated using a dry contact method using a KES-F7 Thermolab II tester manufactured by Kato Tech. The dry contact method is a method assuming that the skin and clothes are directly touched in a dry state. One knitted fabric cut into a 20 cm × 20 cm rectangle was used as a test piece (sample). The test piece was set on a hot plate set at a constant temperature (30 ° C.), and the amount of heat (a) dissipated through the test piece was determined under the condition of the wind speed in the wind tunnel of 30 cm / second. With no test piece set, the amount of heat (b) dissipated under the same conditions as above was determined, and the heat retention rate (%) was calculated according to the following formula.
Thermal insulation rate (%) = (1−a / b) × 100

From the measurement results, the heat retention index was determined according to the following formula B.
Formula B: Thermal insulation index = Heat retention ratio (%) / Sample weight (g / m ² )

Table 15 shows the calculation results of the heat retention index. It can be evaluated that the higher the heat retention index, the better the heat retention material.

As shown in Table 15, it can be seen that the modified fibroin (PRT966 and PRT799) fibers have a higher heat retention index and superior heat retention compared to existing materials.

DESCRIPTION OF SYMBOLS 1 ... Extrusion apparatus, 2 ... Undrawn yarn manufacturing apparatus, 3 ... Wet heat drawing apparatus, 4 ... Drying apparatus, 6 ... Dope liquid, 10 ... Spinning apparatus, 20 ... Coagulating liquid tank, 21 ... Drawing bath, 36 ... Artificial fibroin fiber 38 ... High shrinkage artificial fibroin fiber, 40 ... Production equipment, 42 ... Feed roller, 44 ... Winder, 46 ... Water bath, 48 ... Dryer, 54 ... Heater, 56 ... Tension roller, 58 ... Hot roller, 60 ... Processing Apparatus, 62 ... drying apparatus, 64 ... dry heat plate.

Claims

Shrinked artificial fibroin fiber comprising modified fibroin,
A highly shrinkable artificial fibroin fiber having a shrinkage rate defined by the following formula of 2% or more.
Shrinkage rate = {1− (length of artificial fibroin fiber made wet by contact with water / length of artificial fibroin fiber after spinning and before contact with water)} × 100 (%)
The high-shrinkage artificial fibroin fiber according to claim 1, wherein the modified fibroin is a modified spider silk fibroin.
The high-shrinkage artificial fibroin fiber according to claim 1 or 2, which has been shrunk by contact with water having a boiling point below.
The high-shrinkage artificial fibroin fiber according to claim 3, wherein the temperature of the water is 10 to 90 ° C.
The high shrinkage artificial fibroin fiber according to claim 3 or 4, wherein the shrinkage ratio is 7% or less.
A step of contacting an artificial fibroin fiber containing modified fibroin with water having a boiling point lower than that,
The manufacturing method of the high shrinkage artificial fibroin fiber whose shrinkage rate defined by a following formula is 2% or more.
Shrinkage rate = {1− (length of artificial fibroin fiber made wet by contact with water / length of artificial fibroin fiber after spinning and before contact with water)} × 100 (%)
The method for producing a high-shrinkage artificial fibroin fiber according to claim 6, wherein the modified fibroin is a modified spider silk fibroin.
The method for producing high-shrinkage artificial fibroin fiber according to claim 6 or 7, wherein the temperature of the water is 10 to 90 ° C.
The method for producing high-shrinkage artificial fibroin fiber according to any one of claims 6 to 8, wherein the shrinkage rate is 7% or less.
A step of contacting an artificial fibroin fiber containing modified fibroin with water having a boiling point lower than that,
A shrinkage method of artificial fibroin fiber, wherein the shrinkage rate defined by the following formula is 2% or more.
Shrinkage rate = {1− (length of artificial fibroin fiber made wet by contact with water / length of artificial fibroin fiber after spinning and before contact with water)} × 100 (%)
The method for shrinking artificial fibroin fiber according to claim 10, wherein the modified fibroin is a modified spider silk fibroin.
The method for shrinking artificial fibroin fiber according to claim 10 or 11, wherein the temperature of the water is 10 to 90 ° C.
The method for shrinking artificial fibroin fiber according to any one of claims 10 to 12, wherein the shrinkage ratio is 7% or less.
The modified fibroin comprises a domain sequence represented by Formula 1: [(A) n motif-REP] m ;
The domain sequence has an amino acid sequence with a reduced content of (A) n motif corresponding to deletion of at least one or more (A) n motifs compared to naturally occurring fibroin,
The high shrinkage artificial fibroin fiber according to any one of claims 1 to 5.
[In Formula 1, (A) n motif represents an amino acid sequence composed of 2 to 27 amino acid residues, and (A) the number of alanine residues relative to the total number of amino acid residues in n motif is 83% or more. . REP indicates an amino acid sequence composed of 10 to 200 amino acid residues. m represents an integer of 2 to 300. A plurality of (A) n motifs may have the same or different amino acid sequences. Plural REPs may have the same amino acid sequence or different amino acid sequences. ]
The modified fibroin comprises a domain sequence represented by Formula 1: [(A) n motif-REP] m ;
Compared with naturally occurring fibroin, the content of glycine residues corresponding to at least one or more glycine residues in REP being replaced with another amino acid residue was reduced in the domain sequence. Having an amino acid sequence,
The high shrinkage artificial fibroin fiber according to any one of claims 1 to 5.
[In Formula 1, (A) n motif represents an amino acid sequence composed of 2 to 27 amino acid residues, and (A) the number of alanine residues relative to the total number of amino acid residues in n motif is 83% or more. . REP indicates an amino acid sequence composed of 10 to 200 amino acid residues. m represents an integer of 2 to 300. A plurality of (A) n motifs may have the same or different amino acid sequences. Plural REPs may have the same amino acid sequence or different amino acid sequences. ]
The modified fibroin comprises a domain sequence represented by Formula 1: [(A) n motif-REP] m ;
The domain sequence has one or more amino acid residues in REP substituted with amino acid residues having a higher hydrophobicity index and / or one or more hydrophobicity in REP compared to naturally occurring fibroin. Having an amino acid sequence including a region having a large hydrophobic index, which corresponds to insertion of an amino acid residue having a large sex index,
The high shrinkage artificial fibroin fiber according to any one of claims 1 to 5.
[In Formula 1, (A) n motif represents an amino acid sequence composed of 2 to 27 amino acid residues, and (A) the number of alanine residues relative to the total number of amino acid residues in n motif is 83% or more. . REP indicates an amino acid sequence composed of 10 to 200 amino acid residues. m represents an integer of 2 to 300. A plurality of (A) n motifs may have the same or different amino acid sequences. Plural REPs may have the same amino acid sequence or different amino acid sequences. ]
The modified fibroin comprises a domain sequence represented by Formula 1: [(A) n motif-REP] m or Formula 2: [(A) n motif-REP] m- (A) n motif;
Glutamine residue content corresponding to the domain sequence having one or more glutamine residues in REP deleted or substituted with other amino acid residues compared to naturally occurring fibroin Has a reduced amino acid sequence,
The high shrinkage artificial fibroin fiber according to any one of claims 1 to 5.
[In Formula 1 and Formula 2, (A) n motif represents an amino acid sequence composed of 2 to 27 amino acid residues, and (A) the number of alanine residues is 80% with respect to the total number of amino acid residues in n motif. That's it. REP indicates an amino acid sequence composed of 10 to 200 amino acid residues. m represents an integer of 2 to 300. A plurality of (A) n motifs may have the same or different amino acid sequences. Plural REPs may have the same amino acid sequence or different amino acid sequences. ]
The high-shrinkage artificial fibroin fiber according to any one of claims 1 to 5, wherein the modified fibroin has a limiting oxygen index (LOI) value of 26.0 or more.
The high-shrinkage artificial fibroin fiber according to any one of claims 1 to 5, wherein the maximum hygroscopic exotherm obtained according to the following formula A of the modified fibroin is more than 0.025 ° C / g.
Formula A: Maximum moisture absorption exotherm = {(maximum value of sample temperature when the sample is placed in a low humidity environment until the sample temperature reaches equilibrium and then transferred to a high humidity environment) − (sample Sample temperature when placed in a low-humidity environment until the temperature reaches equilibrium and then moved to a high-humidity environment)} (° C.) / Sample weight (g)
[In Formula A, a low humidity environment means an environment with a temperature of 20 ° C. and a relative humidity of 40%, and a high humidity environment means an environment with a temperature of 20 ° C. and a relative humidity of 90%. ]