JP5274795B2 - Protein refolding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for refolding by which a high-purity protein having a relatively large molecular weight can be produced with good productivity without greatly diluting the high-purity protein. <P>SOLUTION: The method for refolding is carried out as follows. A protein is initially treated with an aggregation inhibitor (A) and then subsequently treated with a refolding agent (B) composed of a compound (B1) having a group represented by general formula (1) and/or a compound (B2) having an oxycarbonyl group in the method for refolding the unfolded protein. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a protein refolding method, and more particularly, to a refolding method for unwinding an unfolded protein into an active protein structure.

  Elucidation and analysis of protein functions and structures are extremely important, for example, directly related to disease treatment and drug discovery. For this reason, various proteins are synthesized and produced by various methods, their structures are examined, and action mechanisms and roles in the living body are elucidated. Now, it is well known that the functions of proteins are determined not only by the sequence and chain length of the amino acids constituting them, but also by the ordered three-dimensional structure (higher order structure) taken by them.

Industrially, with the development of genetic engineering, various proteins have been prepared in large quantities as recombinants and used in a wide variety of industries such as pharmaceutical manufacturing, food processing, and clinical diagnosis. With the development of vector technology, technology that produces a large amount of target protein in Escherichia coli and yeast cells can be easily and reproducibly executed with few resources.
However, many of the proteins expressed in recombinants are unordered in their three-dimensional structure, their higher-order structures are not controlled, and often form small particle granules called inclusive inclusion bodies (inclusion bodies). . For this reason, in the production process by E. coli, the inclusion body is unwound (unfolded), the higher-order structure is prepared, and the protein is converted into a soluble protein with an ordered three-dimensional structure, that is, the inclusion body is unfolded and then refolded. It is necessary to (rewind).

  This type of refolding is an extremely important technique that can be applied not only to proteins produced by E. coli and yeast, but also to the regeneration of proteins inactivated due to certain causes such as thermal history. Therefore, this refolding has been extensively studied and various methods have been proposed, but most of them have a low refolding rate and a certain limited protein (especially a specific protein having a low molecular weight). In many cases, this refolding is general, universal, and has a high refolding rate applicable to various proteins. It is not an efficient and economical method.

The refolding operation that has been used for a long time is the dialysis method and the dilution method.
In the dialysis method, a protein denaturing agent (an unfolding agent such as guanidine hydrochloride and / or urea) added in advance by dialysis is gradually diluted and replaced with a buffer solution to obtain a functional protein three-dimensional structure. It is a method of refolding. As an application example of this method, a stepwise dilution method is known in which the yield of refolding to a functional protein tertiary structure is increased by further slowly decreasing the protein denaturant concentration (for example, non-patented). Reference 1).
However, the dialysis method is not practical in industry because the external solution usually requires a volume of 100 times or more of the protein solution and requires several days of time.

The dilution method is widely used because it ends in a relatively short time and requires a relatively small volume compared to the dialysis method. In the dilution method, an unfolded protein solution to which a protein denaturant (unfolding agent) is added is excessively diluted with a buffer solution to refold the protein from an unfolded state to a functional protein structure. It is a method to do. The dilution method is the simplest and low-cost method for refolding a protein into a functional three-dimensional structure, but the yield of refolding is poor (for example, Non-Patent Document 2), and the yield is low due to large dilution. is the current situation.

When β-cyclodextrin or cycloamylose is used as an artificial chaperone and a protein unfolded with a surfactant is mixed into this chaperone solution, the surfactant is taken up by the artificial chaperone, and the protein is refolded in this process. There are also reports (Non-Patent Documents 3 to 5). However, this method is only successful with carbonic anhydrase B and the like. Moreover, it is not a method that can be repeated, but is expensive.
J Biol Chem. 2003 Mar 14; 278 (11): 8979-8987. J Immunol Methods. 1998 Oct 1; 219 (1-2): 119-129. J. et al. Am. Chem. Soc. Vol. 117 (1995) 2373-2374 J. et al. Biol. Chem. Vol. 271 (1996) 3478-3487 FEBS Lett. Vol. 486 (2000) 131-135

As described above, various refolding methods have been proposed, but when refolding an unfolded protein, there were still problems such as a decrease in yield and low purity due to large dilution of the protein. . Further, when a refolding agent is added to a protein having a relatively large molecular weight, aggregation and precipitation often occur, and the yield is markedly reduced.

As a result of intensive studies to solve the above problems, the present inventors have reached the present invention.
That is, the present invention provides a method for refolding an unfolded protein, in which a protein is treated with 25 to 500% by weight of a nonionic surfactant (A1) based on the weight of the protein, and then phosphoric acid and pyrophosphoric acid are used. From one or more compounds (B1) selected from the group consisting of tripolyphosphoric acid and salts thereof, or one or more compounds (B2) selected from the group consisting of aliphatic carboxylic acids having 1 to 8 carbon atoms and salts thereof A refolding method (B), wherein the nonionic surfactant (A1) is a higher alcohol alkylene oxide adduct and a polyhydric alcohol type nonionic surfactant. In the step of treating the protein with the refolding agent (B), the system of the compound (B1) Concentration in the system of concentration 1 to 6 mol / L or compound (B2) is a refolding method 1 to 6 mol / L.

Moreover, this invention is a protein production method including the process of refolding by the said method.

When the refolding method of the present invention is used, protein aggregation hardly occurs at the time of refolding, and it is not necessary to dilute the protein greatly. Therefore, productivity is dramatically improved as compared with the conventional method. Moreover, since the refolding effect is higher than before, a high-purity protein can be obtained in large quantities.

  The present invention relates to a method for refolding an unfolded protein, wherein the protein is first treated with an aggregation inhibitor (A), and then the compound (B1) having a group represented by the general formula (1) and / or A refolding method comprising treating with a refolding agent (B) comprising a compound (B2) having an oxycarbonyl group.

The aggregation inhibitor (A) in the refolding method of the present invention is an agent that prevents the protein from aggregating when the refolding agent (B) is added and during the subsequent standing.
Examples of the aggregation inhibitor (A) include surfactants, and the following nonionic surfactants, cationic surfactants, anionic surfactants, and amphoteric surfactants.

  Nonionic surfactants include alkylene oxide (hereinafter abbreviated as AO) adducts of higher alcohols [for example, higher alcohols having 8 to 24 carbon atoms (decyl alcohol, dodecyl alcohol, coconut oil alkyl alcohol, octadecyl alcohol). And oleyl alcohol, etc.) ethylene oxide (hereinafter abbreviated as EO) 1-20 mol adducts, etc.]; AO adducts of alkylphenols having alkyl of 6-24 carbons (Triton-X100, Triton-X300, etc.) Polypropylene glycol EO adducts and polyethylene glycol PO adducts; pluronic surfactants, fatty acid AO adducts, and polyhydric alcohol nonionic surfactants (TWEEN20, TWEEN40, TWEEN60, TWEEN) 0, etc.), and the like.

  Examples of the cationic surfactant include a quaternary ammonium salt type cationic surfactant and an amine salt type cationic cationic surfactant.

  Examples of the anionic surfactant include ether carboxylic acid or a salt thereof, sulfate ester or ether sulfate ester and salt thereof, sulfonate, sulfosuccinate, fatty acid salt, acyl having a hydrocarbon group having 8 to 24 carbon atoms. And naturally occurring carboxylic acids and salts thereof (eg, chenodeoxycholic acid, cholic acid, deoxycholic acid, etc.).

Examples of amphoteric surfactants include betaine-type amphoteric surfactants and amino acid-type amphoteric surfactants.
Examples of the surfactant include surfactants described in JP-B-57-39678, in addition to the above.

As the aggregation inhibitor (A) in the refolding method of the present invention, the above nonionic active agent is preferable from the viewpoint of little interaction with protein.
More preferred are alkylene oxide adducts of higher alcohols and polyhydric alcohol type nonionic surfactants.

  The addition amount of the aggregation inhibitor (A) is usually 1000 parts or less with respect to 100 parts of the protein, preferably 1 to 500 parts, more preferably 2 to 300 parts from the viewpoint of the aggregation suppression effect.

  In the present invention, P in the general formula (1) is a phosphorus atom, and examples of the compound (B1) having a group represented by the general formula (1) include inorganic phosphoric acid and salts thereof (B1-1); Acid esters and salts thereof (B1-2); and sugar phosphate esters and salts (B1-3) thereof.

As inorganic phosphoric acid and its salt (B1-1), phosphoric acid, hypophosphorous acid, phosphorous acid, hypophosphoric acid, pyrophosphoric acid, pyrophosphorous acid, metaphosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and these Salt.
Salts include alkali metal salts (sodium salt, potassium salt, lithium salt, etc.), alkaline earth metal salts (calcium salt, magnesium salt, barium salt, etc.), ammonium salt, amine salt (primary amine salt, secondary amine salt). Tertiary amine salts), and quaternary ammonium salts (such as tetraalkylammonium salts).
Specific examples of the salt of (B1-1) include phosphoric acid monohydrogen disodium salt, phosphoric acid dihydrogen monosodium salt, phosphoric acid monohydrogen dipotassium salt, phosphoric acid dihydrogen monopotassium salt, and ammonium phosphate. Salts, phosphates such as tetramethylammonium phosphate, tetraethylammonium phosphate, triethylamine phosphate and triethanolamine phosphate; sodium phosphite, potassium phosphite, ammonium phosphite salt, phosphorous acid Phosphites such as tetramethylammonium acid salt, tetraethylammonium phosphite salt, triethylamine phosphite salt and triethanolamine phosphite salt; sodium pyrophosphate salt, potassium pyrophosphate salt, tetramethylammonium pyrophosphate salt, Tetraethylammonium pyrophosphate, triethyl pyrophosphate Like pyrophosphate, such as amine salts and pyrophosphoric acid triethanolamine salts.

Examples of the alkyl phosphate esters and their salts (B1-2) include alkyl phosphate esters having an alkyl group having 1 to 12 carbon atoms (B1-2-1), alkyl pyrophosphate esters (B1-2-2), And alkyltripolyphosphate (B1-2-3).
Examples of the alkyl phosphate ester (B1-2-1) having an alkyl group having 1 to 12 carbon atoms include methyl phosphate ester, ethyl phosphate ester, propyl phosphate ester, 2-propyl phosphate ester, butyl phosphate ester, Examples include 2-butyl phosphate, t-butyl phosphate, pentyl phosphate, hexyl phosphate, cyclohexyl phosphate, octyl phosphate, nonyl phosphate, decyl phosphate.
Examples of the alkyl pyrophosphate ester (B1-2-2) having an alkyl group having 1 to 12 carbon atoms include methyl pyrophosphate ester, ethyl pyrophosphate ester, propyl pyrophosphate ester, 2-propyl pyrophosphate ester, and butyl pyroline. Acid ester, 2-butyl pyrophosphate ester, t-butyl pyrophosphate ester, pentyl pyrophosphate ester, hexyl pyrophosphate ester, cyclohexyl pyrophosphate ester, octyl pyrophosphate ester, nonyl pyrophosphate ester, decyl pyrophosphate ester, etc. .
Examples of the alkyltripolyphosphate (B1-2-3) having an alkyl group having 1 to 12 carbon atoms include methyltripolyphosphate, ethyltripolyphosphate, propyltripolyphosphate, 2-propyltripolyphosphate, butyltripolyline. Acid ester, 2-butyltripolyphosphate, t-butyltripolyphosphate, pentyltripolyphosphate, hexyltripolyphosphate, cyclohexyltripolyphosphate, octyltripolyphosphate, nonyltripolyphosphate, decyltripolyphosphate, etc. .
Examples of the salts of (B1-2-1) to (B1-2-3) include the same alkali metal salts, alkaline earth metal salts, ammonium salts, and amine salts as the salts mentioned in the above (B1-1). And quaternary ammonium salts.

  Sugar phosphates and their salts (B1-3) include adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP) and cyclic adenosine monophosphate (c-AMP) The sodium salt, potassium salt, triethylamine salt, triethanolamine salt, etc. are mentioned.

  Of the compound (B1) containing a phosphorus atom, (B1-1) and (B1-3) are preferable from the viewpoint of the refolding effect, and more preferable are phosphoric acid, pyrophosphoric acid, polyphosphoric acid, and adenosine. Triphosphate, adenosine diphosphate, adenosine monophosphate and their salts.

The compound (B2) having an oxycarbonyl group in the present invention is characterized by having an oxycarbonyl group (—COO—).
Examples of the compound (B2) include a compound (B2-1) having at least one carboxyl group (—COOH) or one carboxylate anion group (—COO ⁻ ) in the molecule, and at least one in the molecule. Compound (B2-2) having an ester group (—COOR). In addition, oxycarboxylic acids such as lactic acid having these oxycarbonyl group and hydroxyl group at the same time are also included.

  Examples of the compound (B2) having at least one carboxyl group or carboxylate anion group in the molecule include the following carboxylic acids, ether carboxylic acids, and salts thereof.

  As the carboxylic acid in (B2), an aliphatic carboxylic acid (B2-1-1) and an aromatic carboxylic acid (B2-1-1-) having 1 to 36 carbon atoms (including the carbon atom of the carbonyl group, the same shall apply hereinafter). 2).

  As aliphatic carboxylic acid (B2-1-1), C1-C36 aliphatic saturated monocarboxylic acid (formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid , Verargonic acid, lauric acid, myristic acid, stearic acid, behenic acid, 2-ethylhexanoic acid, etc.); C3-36 aliphatic unsaturated monocarboxylic acids (acrylic acid, methacrylic acid, oleic acid, etc.); carbon C3-C36 aliphatic oxycarboxylic acid (glycolic acid, lactic acid, tartaric acid, gluconic acid, etc.); C2-C36 aliphatic saturated dicarboxylic acid (oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, Pimelic acid, suberic acid, azelaic acid, sebacic acid, etc.) and their monoalkyl esters; aliphatic unsaturated dicarboxylic acids having 4 to 36 carbon atoms (maleic acid) Inic acid, fumaric acid, itaconic acid, etc.); and trivalent or higher (preferably 3-12 valent) aliphatic polyvalent carboxylic acids (citric acid, butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, ethylenediaminetetraacetic acid, And diethylenetriaminepentaacetic acid).

Among aromatic carboxylic acids (B2-1-2) among carboxylic acids, aromatic monocarboxylic acids having 7 to 36 carbon atoms (benzoic acid, cinnamic acid, hydroxybenzoic acid, etc.); aromatics having 8 to 36 carbon atoms Aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid, etc.); aromatic tricarboxylic acids and tetracarboxylic acids (trimellitic acid, pyromellitic acid, etc.) having 9 to 36 carbon atoms; aromatic oxycarboxylic acids (salicylic acid, etc.) Can be mentioned.

  As other carboxylic acids, polymers having the above aliphatic unsaturated mono- or dicarboxylic acids as essential constituent monomers (for example, polyacrylic acid, polymaleic acid, acrylic acid / acrylic acid alkyl ester copolymers, etc .: several Average molecular weight 500 to 50,000).

  As the carboxylic acid, a partial alkyl (having 1 to 12 carbon atoms as an alkyl group) ester (for example, monomethyl oxalate, monomethyl succinate, maleic acid) of the above dicarboxylic acid or a trivalent or higher polyvalent carboxylic acid. Monomethyl, monoethyl oxalate, monomethyl citrate, dimethyl citrate, etc.).

Examples of the ether carboxylic acid in (B2-1) include compounds represented by the following general formula (2).

^{R 1 -O- (R 2 O)} p-R 3 -COOH (2)

(In the formula, R ¹ represents a hydrocarbon group having 1 to 36 carbon atoms, R ² represents an alkylene group having 2 to 4 carbon atoms, R ³ represents an alkylene group having 1 to ³ carbon atoms, and p represents an integer of 1 to 50. .)

R ¹ is a hydrocarbon group having 1 to 36 carbon atoms, which is a methyl group, an ethyl group, an n-propyl group, a 2-propyl group, an n-butyl group, a 2-butyl group, a t-butyl group, a pentyl group, Examples include n-hexyl group, cyclohexyl group, octyl group, nonyl group and decyl group.
R2 is an alkylene group having 2 to 4 carbon atoms, and examples thereof include an ethylene group, a 1,2-propylene group, a 1,3-propylene group, a 1,2-butylene group, and a 1,4-butylene group.
R3 is an alkylene group having 1 to 3 carbon atoms, and examples thereof include a methylene group, an ethylene group, a 1,2-propylene group, and a 1,3-propylene group.
p is usually an integer of 1 to 50, preferably 1 to 20, more preferably 1 to 10, and particularly preferably 1 to 4.

  Specific examples of the ether carboxylic acid include polyoxyethylene hexyl ether carboxylic acid, polyoxyethylene octyl ether carboxylic acid, polyoxyethylene nonyl ether carboxylic acid, polyoxyethylene decyl ether carboxylic acid, polyoxyethylene decyl hydroxy ether carboxylic acid, Polyoxyethylene dodecyl ether carboxylic acid, polyoxypropylene hexyl ether carboxylic acid, polyoxypropylene octyl ether carboxylic acid, polyoxypropylene nonyl ether carboxylic acid, polyoxypropylene decyl ether carboxylic acid, polyoxypropylene dodecyl ether carboxylic acid, etc. It is done.

Among the compounds (B2-1), examples of the compound having a carboxylate anion group include salts of the above carboxylic acids or ether carboxylic acids.
Examples of the salt include alkali metal salts alkali, earth metal salt ammonium salt, amine salt and quaternary ammonium salt similar to the salts mentioned in the above (B1).

  Specific examples of the carboxylate include the above aliphatic saturated monocarboxylate having 1 to 36 carbon atoms (sodium formate, ammonium formate, guanidinium formate, sodium acetate, ammonium acetate, guanidinium acetate, sodium propionate, ammonium propionate). Guanidinium propionate, sodium butyrate, sodium caproate, etc.); aliphatic unsaturated monocarboxylic acids having 3 to 36 carbon atoms (such as sodium acrylate); aliphatic oxycarboxylates having 3 to 36 carbon atoms (sodium glycolate) Sodium lactate, ammonium lactate, guanidinium lactate, sodium tartrate, potassium tartrate, ammonium tartrate, guanidinium tartrate, sodium gluconate, etc .; aliphatic saturated dicarboxylates having 2 to 36 carbon atoms (sodium oxalate, succinic acid) Thorium, sodium glutarate, etc.); aliphatic unsaturated dicarboxylates having 4 to 36 carbon atoms (sodium maleate, etc.); salts of the above dicarboxylic acids or partial alkyl esters of trivalent or higher polyvalent carboxylic acids (oxalic acid) Monomethyl sodium, monomethyl sodium succinate, monomethyl potassium maleate, monoethyl sodium oxalate, monomethyl sodium citrate, dimethyl sodium citrate, etc.).

  Examples of ether carboxylates include sodium polyoxyethylene hexyl ether carboxylate, sodium polyoxyethylene octyl ether carboxylate, sodium polyoxyethylene nonyl ether carboxylate, sodium polyoxyethylene decyl ether carboxylate, polyoxyethylene decyl hydroxy ether carboxyl Acid sodium, sodium polyoxyethylene dodecyl ether carboxylate, sodium polyoxypropylene hexyl ether carboxylate, sodium polyoxypropylene octyl ether carboxylate, sodium polyoxypropylene nonyl ether carboxylate, sodium polyoxypropylene decyl ether carboxylate, polyoxy And sodium propylene dodecyl ether carboxylate That.

Examples of the compound (B2-2) having at least one ester group in the molecule include a carboxylic acid alkyl ester (B2-2-1) and an alkylene oxide adduct (B-2-2) of carboxylic acid. .
Examples of the carboxylic acid constituting the carboxylic acid alkyl ester (B2-2-1) include the same carboxylic acids as the compound (B2-1) having at least one carboxyl group or carboxylate anion group in the molecule. It is done.
In addition, as an alkyl group in the ester group, methyl group, ethyl group, n-propyl group, 2-propyl group, n-butyl group, 2-butyl group, t-butyl group, pentyl group, n-hexyl group, cyclohexyl group A linear or branched aliphatic alkyl group having 1 to 12 carbon atoms, such as a group, octyl group, nonyl group or decyl group.

  Specific examples of the carboxylic acid alkyl ester (B2-2-1) include methyl formate, methyl acetate, ethyl formate, ethyl acetate, n-butyl acetate, methyl stearate, and n-butyl stearate); dimethyl oxalate, Dimethyl succinate, dimethyl maleate, diethyl oxalate, diethyl succinate, dimethyl adipate, etc.); those in which all carboxyl groups of trivalent or higher aliphatic polycarboxylic acids are esterified (trimethyl citrate and ethylenediamine) And tetramethyl tetraacetate).

Examples of the alkylene oxide adduct of carboxylic acid include adducts of 1 to 50 mol of alkylene oxide having 2 to 4 carbon atoms with the carboxylic acid mentioned in (B2-1) above.
Examples of the alkylene oxide include ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as PO), and butylene oxide.

  Specific examples of carboxylic acid alkylene oxide adducts include monocarboxylic acid EO adducts (formic acid EO 1-10 mol adduct, acetic acid EO 1-10 mol adduct, propionic acid EO 10 mol adduct, butyric acid EO 1-10 mol addition. Products, caproic acid EO 2-20 mol adduct, lauric acid EO 1-20 mol adduct, etc.); oxycarboxylic acid EO adduct (glycolic acid EO 1-20 mol adduct, lactic acid EO 1-20 mol adduct, tartaric acid PO1- EO adducts of aliphatic polycarboxylic acids (oxalic acid EO 1-20 mol adduct, malonic acid EO 1-20 mol adduct, succinic acid EO 1-20 mol adduct, glutaric acid EO1-20 Mole adduct, citric acid EO 1-20 mol adduct, maleic acid EO 1-20 mol adduct, etc.); aromatic carboxylic acid EO adduct EO1~30 mol adduct of phthalic acid, terephthalic acid EO1~30 mol adduct) and the like.

  Among these compounds (B-2), a compound (B2-1) having a carboxyl group or a carboxylate anion group is preferable from the viewpoint of the refolding effect, and an aliphatic carboxylic acid (B2-1) is more preferable. -1), in particular, aliphatic carboxylic acids having 1 to 8 carbon atoms, such as formic acid, acetic acid, propionic acid, lactic acid, tartaric acid and salts thereof.

The unfolded protein in the present invention may be a protein unfolded by any method, but from the viewpoint of the refolding effect, a protein unfolded by guanidine hydrochloride, urea or a combination thereof is preferable. Guanidine, urea, or a protein unfolded in an aqueous solution having a total concentration of 0.5 mol / L or more is usually used.
When the protein contains an S—S bond in the molecule, it is unfolded by adding 2-mercaptoethanol, dithiothreitol, cystine or thiophenol in addition to guanidine hydrochloride and / or urea. It may be a protein.

The refolding method of the present invention is a method for refolding an unfolded protein, and includes a step of treating the protein with the above-mentioned refolding agent. In this step, in the case of the phosphorus-containing refolding agent (B1), a system is used. The concentration of the compound (B1) is usually 0.2 to 6 mol / L. In the case of the oxycarbonyl group-containing refolding agent (B2), the concentration of the compound (B2) in the system is usually It is a method used at 0.01 to 6 mol / L.
In the case of the phosphorus-containing refolding agent (B1), the concentration of (B1) in the system is usually 0.2 mol / L or more, preferably 0.3 mol / L or more, more preferably 0.5 mol / L. That's it. By being in this concentration range, the effect | action which returns the structure of the unfolded protein to a normal structure can be expressed effectively.
When the concentration of (A) is too low, the refolding effect (ratio at which the unfolded protein can be refolded) is poor.

The phosphorus compound (B1) in the present invention is such that when the concentration in the system is 0.2 mol / L or more, a hydrogen bond between the group represented by the general formula (1) and the protein is easily formed. Estimated to reach equilibrium concentration.
Conventionally, in the refolding process, a general phosphoric acid compound (for example, phosphoric acid / sodium phosphate, etc.) may be used as a buffering agent. / L or less, and at most 0.05 mol / L or less, no refolding action was observed.
In addition, if the concentration of the phosphorus compound (B1) in the system is too high, the viscosity of the system tends to increase, which makes it difficult to separate and purify the protein in the subsequent protein production step.

In the case of the oxycarbonyl group-containing refolding agent (B2), the concentration of (B2) in the system is 0.01 mol / L or more, preferably 0.02 mol / L or more, more preferably 0.1 mol / L. That's it. By being in this concentration range, the effect | action which returns the structure of the unfolded protein to a normal structure can be expressed effectively.
When the concentration of (B2) is too low, the refolding effect (ratio at which the unfolded protein can be refolded) is poor.
(B2) in the present invention is estimated to reach an equilibrium concentration at which a specific hydrogen bond between an oxycarbonyl group and a protein is easily formed when the concentration in the system is 0.01 mol / L. The
In addition, when the concentration of (B2) in the system is too high, the viscosity of the system tends to be high, which makes it difficult to separate and purify the protein in the subsequent protein production step.

  In the present invention, the “step of treating the protein with a refolding agent” is a step of stirring and mixing the protein and the refolding agent to such an extent that a heterogeneous portion is eliminated. In order to proceed to the above, it is also included to stand for a certain period of time if necessary. The standing time is, for example, 1 to 50 hours.

  In the refolding method of the present invention, the refolding effect can be improved by further adding a pH adjuster (C) to the aggregation inhibitor (A), the refolding agent (B), or both of them in advance. It is possible and preferable. For example, the aggregation inhibitor (A) may be diluted with a 0.05 mol / L pH adjuster (C) aqueous solution and used.

  Similarly, the refolding effect can be improved by adding the protein stabilizer (D) to (A), (B), or both in advance, which is preferable. For example, (B) may be prepared by diluting with 0.001 mol / L protein stabilizer (D) aqueous solution.

As the pH adjuster (C), Tris (N-tris (hydroxymethyl) methylaminoethanesulfonic acid), HEPES (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid), and phosphate buffer (For example, monosodium dihydrogen phosphate + aqueous hydrochloric acid solution or monosodium dihydrogen phosphate + sodium hydroxide aqueous solution).
In addition, when using a phosphate buffer, since a phosphate buffer is a phosphate, it may overlap with (B1) in this invention. However, as described above, the upper limit of the addition concentration of the phosphate buffer used for the purpose of pH adjustment is at most 0.05 mol / L, and the phosphorus compound (B1) as the refolding agent of the present invention When the pH adjustment is used together with the target phosphate buffer, the concentration in the system of (B1) is preferably 0.2 to 5.95 mol / L.

In general, the refolding operation is performed at pH 7 to 8. The amount of the pH adjuster (C) added is not particularly limited as long as it is adjusted within this range, but is usually limited to the amount added (B1). Is 20% or less, preferably 0.001 to 20% by weight, more preferably 0.01 to 20% by weight from the viewpoint of the refolding effect.
The addition amount of the pH adjuster (C) is usually 20% by weight or less with respect to the addition amount of (B2), preferably 0.001 to 20% by weight from the viewpoint of the refolding effect. More preferably, the content is 01 to 20% by weight.

Examples of the protein stabilizer (D) include reducing agents, polyols, metal ions, chelating reagents and the like.
Examples of the reducing agent include 2-mercaptoethanol, dithiothreitol, ascorbic acid, reduced glutathione and cysteine.
Examples of polyols include glycerin, glucose, sucrose, ethylene glycol, sorbitol and mannitol.
Examples of metal ions include divalent metal ions such as magnesium ions, manganese ions, and calcium ions.
Examples of the chelating reagent include ethylenediaminetetraacetic acid (EDTA) and glycol etherdiamine-N, N, N ′, N′-4 acetic acid (EGTA).

The addition amount of the protein stabilizer (D) is usually 10% by weight or less with respect to the addition amount of (B1), preferably 0.001 to 10% by weight from the viewpoint of the refolding effect, 0.01 to 5% by weight is more preferred.
The amount of the protein stabilizer (D) added is usually 10% by weight or less with respect to the amount of (B2) added, and is preferably 0.001 to 10% by weight from the viewpoint of the refolding effect. More preferably, the content is 01 to 5% by weight.

In the refolding method of the present invention, the protein concentration in the system is preferably 0.2 to 30 mg / mL, more preferably 0.2 to 20 mg / mL, and particularly preferably 0.25 to 5 mg / mL. If it is 0.2 mg / mL or more, it is preferable from the viewpoint of protein production efficiency, and if it is 30 mg / mL or less, the viscosity in the system is rarely excessively high, and thus production efficiency does not decrease.
Moreover, the addition amount (weight) of (B1) and (B2) with respect to the weight of the protein is preferably 5 to 2,000 parts with respect to 1 part of the protein, and more preferably 10 to 1, from the viewpoint of the refolding effect. 000 parts.

The protein production method of the present invention is a protein production method including the step of refolding by the above refolding method.
Since the protein obtained by the protein production method of the present invention is obtained by the above refolding method, it has a higher purity than the conventional method, and it is not necessary to carry out a large dilution, so that a high yield can be obtained.
Examples of the protein production method of the present invention include a production method according to the following sequence of steps.
(1) Protein culturing step: Enzyme or recombinant protein is cultured in a protein producer such as E. coli.
(2) Lysis process: The inclusion body in the protein producing body is removed by using a lysing agent or the like.
(3) Unfolding step: 0.5 mol / L or more unfolding agent and 20 mmol / L or less reducing agent are added to an inclusion body suspension (for example, 10 mg protein / mL), and the mixture is gently stirred and left at room temperature for several hours. .
(4) Refolding step: Add (A) to the unfolded protein suspension, stir lightly, add (B1) or (B2), stir lightly, and leave at room temperature overnight to refold. Do.
(5) Separation / removal step: The target normal protein is separated from the suspension by column chromatography or the like.

Examples of the protein producer in the protein culturing step (1) include the following bacterial cells, Escherichia and Bacillus.
Bacterial cells include streptococci, staphylococci, Escherichia, streptomyces and Bacillus cells, fungal cells such as yeast cells and Aspergillus Genus (Aspergillus) cells, insect cells: eg Drosophila S2 (Spodoptera S2), Spodoptera Sf9 (
Spodoptera Sf9) cells, animal cells: for example, CHO, COS, Hela, C127, 3T3, BHK, 293, and Bowes melanoma cells, plant cells, and the like.
Examples of Escherichia include Escherichia coli (E. coli) K12DH1 [Proc. Natl. Acad. Sci. USA, Volume 60, 160 (1968)], JM103 (Nucleic Acids Research, Vol. 9, 309 (1981)), JA221 (Journal of Molecular Biology). ) 120, 517 (1978)], HB101 [Journal of Molecular Biology, 41, 459 (196) See year)], C600 [Genetics (Genetics) 39 vol, see 440 pp (1954)], MM294 [Nature (Nature) 217 Vol see 1110 pages to (1968)] and the like.
Examples of Bacillus include Bacillus subtilis MI114 (see Gene, 24, 255 (1983)), 207-21 (Journal of Biochemistry 95, 87). Page (1984)].

As a recombinant protein culturing method, an expression vector containing cDNA encoding the target protein is:
(I) A messenger RNA (mRNA) is isolated from the target protein-producing cell, a single-stranded cDNA and then a double-stranded DNA are synthesized from the mRNA, and the complementary DNA is incorporated into a phage or a plasmid.
(Ii) A host is transformed with the obtained recombinant phage or plasmid, and after culture, contains the target DNA by hybridization with a DNA probe encoding a part of the target protein or by immunoassay using an antibody. Isolate phage or plasmid.
(Iii) It can be produced by cutting out the desired cloned DNA from the recombinant DNA and ligating the cloned DNA or a part thereof downstream of the promoter in the expression vector.
Thereafter, the host is transformed with the expression vector and cultured by an appropriate method. Culture is usually performed at 15 to 43 ° C. for 3 to 24 hours, and aeration and agitation can be added as necessary.

  As the lysis method in the lysis process, any of physical disruption by ultrasound, treatment with a lytic enzyme such as lysozyme, treatment with a lysis agent such as a surfactant, etc. can be used. The treatment with a lysis agent described in Japanese Patent Application No. 2005-119133 is particularly preferred from the viewpoint of not denatured useful proteins.

Examples of the unfolding agent used in the unfolding step include guanidine hydrochloride, urea and a combination thereof.
In addition, when the protein is a protein containing an S—S bond in the molecule, 2-mercaptoethanol, dithiothreitol, cystine, thiophenol or the like is further added as a reducing agent in addition to guanidine hydrochloride and / or urea. May be.

  Examples of the packing material used for column chromatography in the protein separation / removal process include silica, dextran, agarose, cellulose, acrylamide, vinyl polymer, etc., and commercially available products such as Sephadex series, Sephacryl series, Sepharose series (above, Pharmacia series). And Bio-Gel series (Bio-Rad) are available.

The protein of the present invention is a protein obtained by the above protein production method.
Examples of the protein obtained by the protein production method of the present invention include enzymes, recombinant proteins, and nucleic acids.

Examples of the enzyme include a hydrolase, an isomerase, an oxidoreductase, a transferase, a synthetic enzyme, and a desorbing enzyme.
Examples of hydrolases include protease, serine protease, amylase, lipase, cellulase, glucoamylase and the like.
An example of the isomerase is glucose isomerase.
Examples of the oxidoreductase include peroxidase.
Examples of the transferase include acyltransferase and sulfotransferase.
Synthetic enzymes include fatty acid synthase, phosphate synthase, citrate synthase and the like.
Examples of the desorption enzyme include pectin lyase.

Examples of the recombinant protein include protein preparations and vaccines.
Examples of protein preparations include interferon α, interferon β, interleukins 1 to 12, growth hormone, erythropoietin, insulin, granular colony stimulating factor (G-CSF), tissue plasminogen activator (TPA), natriuretic peptide, Examples include blood coagulation factor VIII, somatomedin, glucagon, growth hormone releasing factor, serum albumin, calcitonin and the like.
Examples of the vaccine include hepatitis A vaccine, hepatitis B vaccine, and hepatitis C vaccine.

  Nucleic acids include deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

The following examples further illustrate the invention, but the invention is not limited thereto.
Refolding was performed by the methods of Examples 1 to 5 and Comparative Examples 1 to 6 below to obtain proteins.
The state of aggregation at the time of refolding was observed, and the enzyme activity of the obtained protein was measured to evaluate the productivity.

Example 1
1 ml of 10 mg of lysozyme chloride (manufactured by Nacalai Tesque) and 6 mol / L guanidine hydrochloride (manufactured by Wako Pure Chemical Industries) was added to a 10 ml sterilized test tube, and left at room temperature overnight to unfold the lipase.
To this unfolded protein solution, 2 ml of 0.125% TWEEN 80 (“Polysorbate 80”: Sanyo Chemical Industries) was added and stirred gently, followed by 2 mol / L phosphate (disodium monohydrogen phosphate: phosphoric acid). 3 ml of 1 sodium dihydrogen = 1: 1 molar ratio (both manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was allowed to stand overnight at room temperature for refolding (concentration of compound (B) in the system = 1.0 mol / L, concentration of protein in the refolding step in the system = 1.7 mg / mL).

Example 2
Refolding was performed in the same manner as in Example 1 except that 2 mol / L sodium tripolyphosphate (manufactured by Wako Pure Chemical Industries, Ltd.) was added instead of 2 mol / L phosphate (compound (B) in the system). (Concentration = 1.0 mol / L, concentration of protein in the refolding step in the system = 1.7 mg / mL).

Example 3
Refolding was performed in the same manner as in Example 1 except that 2 mol / L sodium acetate salt (manufactured by Wako Pure Chemical Industries, Ltd.) was added instead of 2 mol / L phosphate (compound (B) in the system). (Concentration = 1.0 mol / L, concentration of protein in the refolding step in the system = 1.7 mg / mL).

Example 4
Refolding was performed in the same manner as in Example 1 except that 2 mol / L ammonium acetate (manufactured by Wako Pure Chemical Industries) was added instead of 2 mol / L phosphate (compound (B) in the system). (Concentration = 1.0 mol / L, concentration of protein in the refolding step in the system = 1.7 mg / mL).

Example 5
Instead of 2 mol / L phosphate, 2 mol / L acetate sodium salt (manufactured by Wako Pure Chemical Industries, Ltd.) is added, and instead of 0.125% TWEEN 80, 0.125% oleyl alcohol EO 18 mol adduct (Emalmine 180: Sanyo) Refolding was performed in the same manner as in Example 1 except that 2 ml (made by Kasei Kogyo) was added (concentration of compound (B) in the system = 1.0 mol / L, concentration of protein in the refolding step) = 1.7 mg / mL).

Comparative Example 1
No aggregation inhibitor was added to the unfolded protein solution, and 1.2 mol / L phosphate (monosodium phosphate disodium: sodium dihydrogen phosphate = 1 molar ratio) (both Wako Pure) The procedure was the same as in Example 1 except that only 5 ml of (medicinal product) was added and allowed to stand overnight at room temperature for refolding. (Concentration of compound (B) in the system = 1.0 mol / L, concentration of protein in refolding process in the system = 1.7 mg / mL).

Comparative Example 2
No unfolding protein solution was added to the unfolded protein solution, except that only 5 ml of 1.2 mol / L sodium acetate salt (manufactured by Wako Pure Chemical Industries, Ltd.) was added and left overnight at room temperature for refolding. Was carried out in the same manner as in Example 1. (Concentration of compound (B) in the system = 1.0 mol / L, concentration of protein in refolding process in the system = 1.7 mg / mL).

Comparative Example 3
To this unfolded protein solution, 0.05% TWEEN 80 (“Polysorbate 80”: manufactured by Sanyo Kasei Kogyo Co., Ltd.) and 1.2 mol / L phosphate (disodium monohydrogen phosphate: monosodium dihydrogen phosphate) = 1: 1 molar ratio) (both manufactured by Wako Pure Chemical Industries, Ltd.) and 5 ml of refolding agent were simultaneously added and left to stand overnight at room temperature for refolding (concentration of compound (B) in the system = 1. (0 mol / L, concentration of protein in the refolding step in the system = 1.7 mg / mL).

Comparative Example 4 [Refolding by large dilution-1]
Put 1 ml of unfolded protein solution in a 210 ml sterilized bottle and 200 ml of 0.1 mol / L sodium phosphate buffer (pH = 7: Wako Pure Chemical Industries). I did it. (Concentration of compound (B) in the system: 0.10 mol / L, protein concentration in refolding step: 0.05 mg / mL)

Comparative Example 5 [Refolding by Large Dilution-2]
In a 140 ml sterile bottle, 1 ml of unfolded protein solution and 70 ml of 0.05% cetyltrimethylammonium bromide (CTAB) (manufactured by Tokyo Kasei) are added, and left at room temperature for 1 hour, 2% cycloamylose (Ezaki 30 ml of a solution (manufactured by Glico) was added and left overnight (concentration of compound (B) in the system: 0 mol / L, protein concentration in refolding step = 0.1 mg / mL).

Comparative Example 6 [Refolding by Dialysis]
1 ml of the unfolded protein solution was put into a dialysis machine, 0.1 mol / L Tris buffer (pH = 7: manufactured by Wako Pure Chemical Industries) was gradually added, and diluted gradually to perform refolding. The reaction was completed when 200 ml of Tris buffer was added (concentration of compound (B) in the system: 0 mol / L, protein concentration in refolding step = 0.05 mg / mL).

<Confirmation of aggregation suppression effect>
In Examples 1-5 and Comparative Examples 1-6, the aggregation inhibitory effect during refolding was judged on the following scale.
○: No agglomerates are visually recognized x: Agglomerates are partially observed visually

<Measurement of enzyme activity>
3 ml of a 0.5 weight percent concentration Bacillus subtilis solution was placed in a 10 ml sterilized test tube, and the protein solution obtained in Example 1-5 or Comparative Example 1-6 was added with a 10 μl micropipette and mixed gently. Absorbance (450 nm) was measured for 12 minutes every 3 minutes with an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-2550), and the initial rate Ka of the decomposition reaction was calculated from the rate of decrease in absorbance with respect to time.
Further, “lysozyme” aqueous solutions having the same concentrations as the protein concentrations of Examples 1 to 5 or Comparative Examples 1 to 6 were prepared, and the initial rate Kb of the Bacillus subtilis decomposition reaction was calculated in the same manner as described above.
The enzyme activities (%) of Examples 1 to 5 and Comparative Examples 1 to 6 were calculated by the following formula.
Enzyme activity (%) = (Ka / Kb) × 100

<Evaluation of protein productivity>
Protein productivity was defined and evaluated with the following indicators.
Productivity = protein concentration in the refolding process (mg / mL) x enzyme activity (%)

  Tables 1 and 2 show the evaluation results of the aggregation inhibitory effect, enzyme activity, and productivity of Examples 1-5 and Comparative Examples 1-6.

When the refolding method of the present invention is used, various useful proteins can be produced with high purity and efficiency without aggregation.
Examples of the protein obtained by the protein production method of the present invention include enzymes, recombinant proteins, and nucleic acids.

Claims (7)

In the unfolded protein refolding method, after treating the protein with 25 to 500% by weight of nonionic surfactant (A1) based on the weight of the protein, phosphoric acid, pyrophosphoric acid, tripolyphosphoric acid and their A refolding agent (B) comprising one or more compounds (B1) selected from the group consisting of salts or one or more compounds (B2) selected from the group consisting of aliphatic carboxylic acids having 1 to 8 carbon atoms and salts thereof; ), And the refolding method is characterized by:
The nonionic surfactant (A1) is a higher alcohol alkylene oxide adduct and a polyhydric alcohol type nonionic surfactant,
In the step of treating the protein with the refolding agent (B), the concentration of the compound (B1) in the system is 1 to 6 mol / L or the concentration of the compound (B2) in the system is 1 to 6 mol / L. Folding method. The refolding method according to claim 1, wherein the alkylene oxide adduct of the higher alcohol is an adduct of 1 to 20 mol of ethylene oxide of a higher alcohol having 8 to 24 carbon atoms. The polyhydric alcohol type nonionic surfactant is polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan monooleate according to claim 1 or 2. The refolding method as described. The refolding method according to any one of claims 1 to 3, wherein the unfolded protein is a protein unfolded with guanidine hydrochloride and / or urea. The protein is treated with a nonionic surfactant (A1) and / or a refolding agent (B) in the presence of a pH adjuster (C) and / or a protein stabilizer (D). The refolding method as described. The refolding method according to any one of claims 1 to 5, wherein the protein concentration in the system in the step of treating with the refolding agent (B) is 0.2 to 30 mg / mL. A method for producing a protein comprising a step of refolding by the refolding method according to claim 1.