JP2017222614A - Rare earth ions mineralization agent and use of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a peptide and a mineralization agent utilizing the peptide which are capable of capturing heavy rare earth species such as ytterbium (Yb) and lutetium (Lu) while having selectively high bondability thereto which have been difficult.SOLUTION: A mineralization agent contains amino acid sequence made up of a specific sequence, and selectively captures ytterbium and/or lutetium as rare earth species for any one of gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho) and erbium (Er).SELECTED DRAWING: None

Description

  The present specification relates to a rare earth ion mineralization agent and use thereof.

  In recent years, the use of rare earths, that is, inorganic elements centered on rare earth elements has become essential. On the other hand, there are concerns about the stable supply of rare earth elements and the environmental impact of rare earth elements. Therefore, it is hoped to develop technology to efficiently collect rare earth elements from nature, and to establish technology to selectively and efficiently collect and recycle dilute rare earth elements contained in discarded products and wastewater with low energy. It is rare.

  As a method for recovering such rare earth elements, a method for recovering by utilizing solvent extraction utilizing N, N-dioctyl diglycolamidic acid (DODGAA) or a reducing microorganism has been reported. On the other hand, peptides that bind to rare earth ions such as lanthanoid ions have been reported (Patent Documents 1 and 2).

US Patent Publication No. 2003/0228622 JP 2014-51449 A

  The above-described solvent extraction method and recovery method using a reducing microorganism are difficult to make a profitable cost. Further, the methods of Patent Documents 1 and 2 do not provide peptides that bind or mineralize ytterbium (Yb) or lutetium (Lu) with high specificity among rare earth elements.

  The present specification provides a peptide capable of selectively capturing rare earth species such as Yb and Lu, which have been difficult in the past, and capable of capturing them, and uses thereof.

  The present inventors have already developed a peptide capable of capturing or recovering dysprosium oxide or neodymium oxide. As a result of producing and searching for mutants of this peptide, it was found that certain peptides can bind to heavy rare earth ions such as Yb and Lu with high selectivity and can be mineralized.

[1] A mineralization agent of a rare earth species having an ability to capture rare earth species that are rare earth minerals and / or rare earth ions,
-X1-X2-X3-A1-X4-X5-A2-X6-A3-X7-X8- (SEQ ID NO: 1)
(However, A1 to A3 are each independently an acidic amino acid, X1 is leucine, isoleucine, valine or threonine, X2 is alanine, glycine, serine or asparagine, and X3 is glycine, isoleucine, Cysteine, serine, arginine, X4 is valine, serine, arginine, methionine, phenylalanine or leucine, X5 is serine, leucine, arginine, glycine, cysteine, asparagine or lysine, and X6 is leucine, lysine, Valineserine or glycine, X7 is phenylalanine, glycine, leucine, threonine, isoleucine, valine, tryptophan or histidine, X8 is leucine, valine, threonine, serine, asparagine, phenylara Emissions, is a glutamic acid.)
An amino acid sequence represented by
A mineralization agent that captures ytterbium (Yb) and / or lutetium (Lu) as the rare earth species.
[2] The amino acid sequence is Leu-Ala / Gly / Ser / Asn-Gly-Asp / Glu-Val-Ser / Asn-Asp / Glu-Leu / Val-Asp / Glu-Phe / Leu-Leu (SEQ ID NO: The mineralization agent according to [1], represented by 2).
[3] Selectively capture ytterbium and / or lutetium for any of gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho) and erbium (Er), [1] or [ 2].
[4] The amino acid sequence is represented by Leu-Ala / Gly / Ser / Asn-Gly-Asp-Val-Ser-Glu-Leu-Asp-Phe-Leu (SEQ ID NO: 2), [1] to [1] 3] The mineralization agent according to any one of [3].
[5] The mineralization agent according to any one of [1] to [4], which is a cyclic peptide containing the amino acid sequence.
[6] A separation target that may contain ytterbium (Yb) and / or lutetium (Lu) as a rare earth species that is a rare earth mineral and / or a rare earth ion, and a rare earth according to any one of [1] to [5] A step of contacting the seed mineralization agent,
A method for separating rare earth species.
[7] The method according to [6], wherein the rare earth species is ytterbium ion.
[8] The method according to [6], wherein the rare earth species is lutetium ion.
[9] A mineralization target that may contain ytterbium (Yb) ions and / or lutetium (Lu) ions, and a rare earth species mineralization agent according to any one of [1] to [5]. Contacting and mineralizing ytterbium ions and / or lutetium ions;
A mineralization method for rare earth ions.
[10] A detection target that may contain ytterbium (Yb) ions and / or lutetium (Lu) ions is contacted with the rare earth species mineralization agent according to any one of [1] to [5]. Detecting ytterbium ions and / or lutetium ions,
A method for detecting rare earth ions.
[11] Contacting a composite object that may contain ytterbium (Yb) ions and / or lutetium (Lu) ions with the rare earth species mineralization agent according to any one of [1] to [5] A step of forming a complex of a ytterbium ion and / or a lutetium ion and a peptide,
A method for producing a rare earth composite.

It is a figure which shows the amino acid sequence of the alanine substitution product of mineralization peptide Lamp1- of heavy rare earth ion. It is a figure which shows the mineralization evaluation result (after 15 minutes) of various alanine substitution products. It is a figure which shows the mineralization evaluation result (after progress for 15 minutes, 1 hour, and 18 hours) of each alanine substituted body in order from an upper stage, respectively. It is a figure which shows the chromatogram of the gel filtration chromatography of various alanine substitution products. It is a figure which shows the amino acid sequence of various substitution products of 4th-position tryptophan of Lamp-1 peptide. It is a figure which shows the mineralization evaluation result of various substitution products of 4-position tryptophan of Lamp-1 peptide.

  The disclosure of the present specification relates to agents and methods for capturing, detecting, separating and the like of rare earth species, particularly rare earth species derived from ytterbium and / or lutetium. The rare earth species mineralization agent disclosed herein (hereinafter also simply referred to as the present mineralization agent) selectively captures ytterbium ions and / or lutetium ions even in the presence of other rare earth species. Can be detected and separated. The present mineralization agent has a selective mineralization ability to selectively mineralize ytterbium ions and / or lutetium ions, and can capture, detect, and separate rare earth species.

  In this specification, the rare earth mineralization ability is the ability to capture rare earth ions and mineralize them into hydroxides. More specifically, the rare earth mineralization ability is determined by the fact that the mineralization agent is used in the liquid medium in which the rare earth ions are present, from the rare earth ions and the counter ions in the liquid medium to the rare earth hydroxide, etc. Ability to generate rare earth minerals.

  In the present specification, a combination of mineralization ability for two or more rare earth ions in the rare earth ion series is referred to as a mineralization tendency. In terms of the mineralization trend, which rare earth ions will exhibit the mineralization ability, and what level of mineralization will be possible for the rare earth ions to be minarized This includes both the point regarding the strength (easyness) of the mineralization ability.

  According to the present disclosure, for example, in a rare earth ion series composed of 17 rare earth ions ranging from scandium (Sc) to lutetium (Lu), it is selective to ytterbium and lutetium and has a high mineralization ability. A mineralization agent having the following can be provided.

  According to the present disclosure, by utilizing the mineralization tendency of such a mineralization agent, rare earth ion series ytterbium and lutetium ions can be captured, detected, separated, and the like as rare earth minerals.

  Further, according to the present disclosure, in addition to the mineralization agent of the present disclosure, one or two or more mineralization agents are separately used, and the difference in the tendency of mineralization is effectively utilized to make rare earths efficiently. Ions can be separated and detected.

  In this specification, “rare earth” means two elements of scandium (Sc) and yttrium (Y), and the lanthanoid lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), and promethium (Pm). , Samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu) Is mentioned.

  In the present specification, “rare earth ion” or “rare earth ion” includes ions having a valence of a potential oxidation number for each rare earth. In the present specification, the “rare earth ion series” means an aggregate of all 17 rare earth ions ranging from scandium to lutetium.

  As used herein, “rare earth minerals” include oxides, hydroxides, inorganic acid salts and organic acid salts with possible oxidation numbers for each rare earth. The rare earth mineral produced by the mineralization agent of the rare earth ion in the aqueous medium is typically a hydroxide.

  In this specification, “light rare earth” includes scandium (Sc), lanthanoid lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), and promethium (Pm). In this specification, the “light rare earth ion series” means an assembly of ions having a valence of oxidation that can be nine types of light rare earths.

  In the present specification, “medium rare earth” includes samarium (Sm), europium (Eu), and gadolinium (Gd). In this specification, the “medium rare earth ion series” means an assembly of ions having a valence of oxidation that can be three types of medium rare earths.

  In this specification, “heavy rare earth” means yttrium (Y), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium ( Lu). In the present specification, the term “heavy rare earth ion series” means a set of ions having a valence of oxidation that can be eight kinds of heavy rare earths.

  In the present specification, the “rare earth species” includes rare earth ions and rare earth minerals.

(Mineralization agent)
The mineralization agent disclosed in this specification has a mineralization ability to selectively mineralize ytterbium and lutetium with respect to the rare earth series.

(Mineralization domain)
The mineralization agent can form a cyclic structure when in proximity to a rare earth ion or can itself have a cyclic structure. It is speculated that the region of the cyclic structure that can be formed by the mineralization agent is related to the mineralization ability. Hereinafter, the region related to the cyclic structure is also referred to as a mineralization region. Examples of the compound capable of constituting such a mineralization region include a polymer in which a plurality of units are linked by a rotatable bond.

  The mineralization region is configured as a peptide chain, for example. Peptide chains in which amino acids are linked by peptide bonds can change their bond angles (φ, ψ) based on interactions with side chains and surroundings, and can adopt various three-dimensional structures, and amino acid residues. The size of the ring structure can also be controlled by the number of bases.

  In the present specification, a peptide is usually a polymer in which several or more natural amino acids and / or unnatural amino acids are linked by acid amide bonds. Peptides generally have about 50 amino acid residues or less. The peptide is preferably a polymer of L-form amino acid residues, but does not exclude the fact that it is a D-form polymer.

  When the mineralization region is a peptide chain, the mineralization region may be linear or may be cyclized by an intramolecular disulfide bond or the like. If it is cyclized, the mineralization ability can be exhibited more efficiently. In addition, since the peptide chain can form a disulfide bond in advance using S (sulfur atom) of S-containing amino residues such as cysteine, it can be cyclized at a predetermined site and a closed cyclic structure is easy. Can be formed. Furthermore, by appropriately selecting the number of residues and amino acid residues, a mineralization region capable of forming a cyclic structure exhibiting a desired mineralization tendency with a desired inner diameter can be constructed. It should be noted that the cyclization of the mineralization region by cysteine residues can be easily realized by adding an oxidizing agent such as iodine or hydrogen peroxide to peptides containing cysteine residues.

(Mineralization sequence)
The mineralization region comprising a peptide chain can be provided with an amino acid sequence of 8 to 14 amino acid residues as an amino acid sequence (mineralization sequence) for exerting the mineralization ability. According to the mineralization region having such a number of residues, mineralization agents having various mineralization tendencies with respect to the rare earth ion series can be designed. If it is less than 8, an effective cyclic structure cannot be formed, and if it exceeds 14, the mineralization ability selective to the rare earth ion series is reduced, while the mineralization ability for other ions is exhibited. become.

  The mineralization region may have a mineralization sequence as a part thereof or may consist only of the mineralization sequence. The mineralization sequence is more preferably composed of 10 to 14 amino acid residues.

  Considering the formation of a cyclic structure, it is preferable that both ends of the mineralization sequence are cysteine residues. For example, in the case of a mineralization sequence consisting of 10 or more and 14 or less amino acid residues, if both ends are cysteine residues, the amino acid sequence between both cysteine residues is 8 or more and 12 or less amino acid residues. An amino acid sequence consisting of

  The mineralization sequence preferably contains one or more acidic amino acid residues. Examples of the acidic amino acid residue include glutamic acid, aspartic acid, isoaspartic acid, isoglutamic acid, 2-aminoadipic acid, 2-aminosuberic acid and the like. Preferred are aspartic acid and glutamic acid. Two or more acidic amino acid residues may be the same or different. The acidic amino acid residue can be 1 to 3 or less, but the acidic amino acid residue may be 3 or more.

  When the mineralization sequence has two or more acidic amino acid residues, the closest acidic amino acid residues may be directly adjacent to each other or through 1 or 2 to 4 amino acid residues. May be adjacent to each other. The type of the intervening amino acid residue (intervening amino acid residue) is not particularly limited, but is preferably intervened by a neutral amino acid residue, an aromatic amino acid residue, or the like. The intervening amino acid residue more preferably includes a neutral amino acid residue.

  Here, examples of the neutral amino acid residue include glycine, alanine, valine, leucine, isoleucine, serine, threonine, and norvaline. Examples of basic amino acid residues include histidine, lysine, arginine, ornithine, norleucine, 2-aminobutanoic acid, 2,4-diaminobutanoic acid, 2,3-diaminopropionic acid, methionine, o-methylserine, and t-butyl. Examples include glycine, t-butylalanine, and cyclohexylalanine. Examples of acid amide amino acid residues include asparagine and glutamine. Examples of cyclic amino acid residues include proline, 3-hydroxyproline, and 4-hydroxyproline. Examples of the OH-containing amino acid residue include serine, threonine, and homoserine. Aromatic amino acid residues include phenylalanine, tyrosine and tryptophan.

  The mineralization region composed of the peptide chain of the present mineralization agent can have an amino acid sequence (mineralization sequence) for mineralizing ytterbium ions or lutetium ions.

The mineralization sequence of the present mineralization agent can comprise, for example, the following amino acid sequence:
(1) -X1-X2-X3-A1-X4-X5-A2-X6-A3-X7-X8-
(However, A1 to A3 are each independently an acidic amino acid, X1 is leucine, isoleucine, valine or threonine, X2 is alanine, glycine, serine or asparagine, and X3 is glycine, isoleucine, Cysteine, serine, arginine, X4 is valine, serine, arginine, methionine, phenylalanine or leucine, X5 is serine, leucine, arginine, glycine, cysteine, asparagine or lysine, and X6 is leucine, lysine, Valineserine or glycine, X7 is phenylalanine, glycine, leucine, threonine, isoleucine, valine, tryptophan or histidine, X8 is leucine, valine, threonine, serine, asparagine, phenylara Emissions, is a glutamic acid.)

  The mineralization tendency of the mineralization sequence is that the mineralization ability is extremely selective to ytterbium and lutetium in the rare earth ion series because X2 is alanine.

  The mineralization sequence X1 is preferably leucine, isoleucine or valine, X3 is preferably glycine, A1 and A3 are each preferably aspartic acid or glutamic acid, X4 is preferably valine, A2 Is preferably glutamic acid or aspartic acid, X5 is preferably serine, arginine, asparagine or lysine, X6 is preferably leucine or valine, X7 is preferably phenylalanine or leucine, and X8 is preferably leucine or valine. Or threonine.

  The mineralization sequence may further comprise one or more amino acid residues at the N-terminus or C-terminus. For example, 1 or 2 amino acid residues may be added, 1 or more and 3 or less amino acid residues may be added, or 1 or more and 5 or less amino acid residues may be added. 1 to 7 or less amino acid residues may be added, 1 to 19 amino acid residues may be added, or 1 to 10 amino acid residues may be added. No more than amino acid residues may be added.

  Examples of amino acid residues that can be provided at the terminal of the mineralization sequence include serine, cysteine, and asparagine. In addition, by introducing cysteine at both ends, the mineralization region can be easily cyclized.

  Considering the formation of a cyclic structure, it is preferable that both ends of the mineralization sequence are cysteine residues. Thus, for example, a cysteine residue can be provided directly or with one or more amino acid residues at the N-terminus and C-terminus of the above-described mineralization sequence. The number of intervening amino acids is preferably small and may not be present.

  Examples of the mineralization sequence (1) include Leu-Ala / Gly / Ser / Asn-Gly-Asp / Glu-Val-Ser / Asn-Asp / Glu-Leu / Val-Asp / Glu-Phe / Leu- An amino acid sequence represented by Leu (SEQ ID NO: 2) is exemplified, and more specifically, an amino acid sequence represented by SEQ ID NO: 3 to 10 is exemplified. These amino acid sequences are examples in which Ala is adopted among Ala, Gly, Ser and Asn, which are the second amino acid residue candidates of the mineralization sequence (1). In the amino acid sequences of SEQ ID NOs: 3 to 10 below, amino acid sequences substituted with any of Gly, Ser and Asn in place of Ala at the fourth position are also disclosed herein. In the amino acid sequences shown below, the mineralization sequence is preferably a sequence excluding one amino acid residue at each of the N-terminal and C-terminal, more preferably two amino acid residues at both terminals, , SC- and -CS. More preferred is a sequence excluding one amino acid group (S) at both ends.

SerCys-LeuAlaGlyAspValSerGluLeuAspPheLeu-CysSer (SEQ ID NO: 3)
SerCys-LeuAlaGlyAspValSerGluLeuGluPheLeu-CysSer (SEQ ID NO: 4)
SerCys-LeuAlaGlyGluValSerGluLeuGluPheLeu-CysSer (SEQ ID NO: 5)
SerCys-LeuAlaGlyGluValSerGluLeuAspPheLeu-CysSer (SEQ ID NO: 6)
SerCys-LeuAlaGlyAspValSerAspLeuAspPheLeu-CysSer (SEQ ID NO: 7)
SerCys-LeuAlaGlyAspValSerAspLeuGluPheLeu-CysSer (SEQ ID NO: 8)
SerCys-LeuAlaGlyGluValSerAspLeuGluPheLeu-CysSer (SEQ ID NO: 9)
SerCys-LeuAlaGlyGluValSerAspLeuAspPheLeu-CysSer (SEQ ID NO: 10)

  The mineralization agent can exhibit a monomer in gel filtration chromatography. According to the present inventors, a peptide having the above-described mineralization sequence and capable of exhibiting a monomer in gel filtration chromatography has a tendency toward mineralization as the atomic number increases for each lanthanoid ion. Was found to change.

  The mineralization region mineralizes ytterbium ions and / or lutetium ions in an aqueous medium by an interaction other than a rare earth ion and a covalent bond. In mineralization, it is considered that such a heavy rare earth ion and a mineralization region can form a complex at least temporarily enough to capture the rare earth ion. Non-covalent interactions include electrostatic bonds, ionic bonds, hydrogen bonds, and the like, but the interactions related to “trapping” in this specification are not limited to these.

  Note that the mineralization region can also have the ability to capture ytterbium and / or lutetium minerals. When the mineralization ability of these ions is provided, rare earth minerals such as rare earth hydroxides can be generated from a liquid medium containing these ions. For this reason, while separating the ionized rare earth, a rare earth mineral can be produced at once from the ion, and separation and recovery are facilitated, which can greatly contribute to the efficiency of separation and recovery of rare earth species. The mineralization region can also have a capability of capturing rare earth minerals such as rare earth hydroxides.

  When the mineralization agent is a peptide as a whole, it can be obtained by methods well known to those skilled in the art, such as genetic engineering methods in addition to known chemical synthesis methods.

  The mineralization agent may be provided with a labeling substance. By providing the labeling substance, the mineralization agent mineralized with rare earth ions can be easily identified, which is convenient for separation and recovery. The labeling substance is not particularly limited, and various known labeling substances can be used. The labeling substance may be visually identifiable or may emit light by light of a predetermined wavelength. In addition to being colored, it may be capable of coloring by reaction with other compounds. The labeling substance may be held on a carrier such as a bead. Examples of such labeling substances include colored beads, colloidal gold, fluorescent compounds, and enzyme proteins. The labeling substance includes label binding substances such as those using an antibody-antibody reaction and those using a biotin-avidin bond. A label-binding substance is a substance that binds a labeling substance, and such a label-binding substance can also function as a labeling substance.

  The labeling substance is bound by a known method depending on the type of the mineralization agent. When the mineralization agent is a peptide, it is typically attached to the N-terminus and / or C-terminus of the mineralization region via an appropriate number of linker peptides for the mineralization agent.

  Furthermore, the mineralization agent may be provided with a tag so that it can be recovered using affinity chromatography or the like. The tag may be an antigen (epitope) or the like, and in addition to a known His tag, biotin or the like can be used. Such tags may be linked via a suitable linker.

  Further, by obtaining an antibody against the mineralization agent and using the antibody, the mineralization agent can be identified and detected without any labeling of the mineralization agent.

(Rare earth ion separation method)
Separation or identification of rare earth ions by the present mineralization agent may comprise a step of bringing the present mineralization agent into contact with a separation object that may contain ytterbium ions and / or lutetium ions. Based on the mineralization tendency of the present mineralization agent, ytterbium ions and / or lutetium ions can be mineralized to separate these heavy rare earth ions as rare earth minerals.

  Conditions for the production of rare earth minerals from heavy rare earth ions by the mineralization agent (mineralization conditions) are not particularly limited as long as the mineralization ability of the mineralization agent is exhibited. What is necessary is just to contact the isolation | separation object and a rare earth ion on suitable conditions, and to incubate as needed.

  Mineralization conditions are different conditions in the pH, temperature, and salt concentration of the liquid medium, the separation target and the mineralization agent are brought into contact with each other, and the rare earth mineral is produced from the rare earth ions by the mineralization agent. You can get it by checking.

  For example, the liquid medium may be any liquid medium as long as the mineralization ability of the mineralization agent can be exhibited. The liquid medium may be an aqueous medium or an organic solvent, or a mixed medium thereof. When the mineralization agent has a peptide chain, it can be considered that the denaturation of the peptide is suppressed or avoided.

  As the liquid medium, typically, a neutral buffer or the like, a mixed liquid containing them, or the like can be used. For example, the pH is not particularly limited, but can be about 5 or more and 8 or less, and the salt concentration is not particularly limited, but can be 10 mM or more and 1 M or less. Further, the temperature is not particularly limited, and can be easily bonded without temperature control. Typically, the temperature can be 4 ° C. or higher and 80 ° C. or lower, more preferably 10 ° C. or higher and 40 ° C. or lower. Preferably, it can be set to 15 ° C or higher and 30 ° C or lower.

  For contact between the rare earth ions and the mineralization agent, the contact efficiency can be increased by stirring as appropriate. The time for contact is not particularly limited, but can be about 10 minutes to several hours, preferably 30 minutes to 8 hours, and the upper limit time is more preferably 6 hours or less. More preferably, it can be about 4 hours or less. More preferably, it can be about 1 hour or more and 3 hours or less.

  In addition, since the production situation and precipitation situation of rare earth minerals by mineralization differ depending on the pH, temperature and / or incubation time, the pH adjustment, temperature adjustment and / or incubation time is appropriately adjusted such as extending or shortening as appropriate. It is preferable.

  The concentration of the mineralization agent and the concentration of the mineralization material in the liquid medium for exerting the mineralization ability of the mineralization agent are not particularly limited. For example, the mineralization agent may have a concentration of 5 μM or more. Preferably, the rare earth ion concentration is 100 μM or more. Further, other mineralization raw materials other than the rare earth ions are preferably the same as the rare earth ion concentration.

  In the case of mineralization of a rare earth ion by a mineralization agent, a rare earth ion for producing a rare earth mineral and an anion such as an inorganic acid ion or a hydroxide ion that forms the mineral with the rare earth ion (a combination of these mineral ions) May be referred to as a raw material for lysation). Among these anions, inorganic acid ions can be present in a liquid medium used for mineralization by addition of an acid or a salt. Further, hydroxide ions can be contained in a liquid medium containing water by ionization of water or the like.

  According to this separation method, ytterbium ions and / or lutetium ions can be separated. Ytterbium ions and / or lutetium ions can be separated and captured as minerals. Moreover, since it can isolate | separate as a mineral, presence of a rare earth ion is easily detectable also by precipitation or precipitation of a rare earth mineral. For example, the generation of rare earth minerals can be confirmed by detecting turbidity using a visible light wavelength such as 600 nm.

  This mineralization agent can selectively and efficiently mineralize ytterbium ions and / or lutetium ions in all rare earth ion series. For this reason, it can be suitably applied to separation objects in which rare earth ions other than ytterbium ions and lutetium ions coexist. Therefore, when it is desired to separate ytterbium ions and lutetium ions, pretreatment such as removing other rare earth ions in advance can be omitted.

  In addition, examples of separation targets that may contain ytterbium ions and / or lutetium ions include those collected from rare earth production sites, and discarded or used materials that may contain these rare earth species. If there is a possibility that a rare earth species that may be contained is not ionized, a material that has been treated in advance such that the rare earth species is a rare earth ion can be used as a separation target. Typically, ionization treatment with a strong acid or the like can be given.

  The rare earth mineral produced by the mineralization can be obtained as an insoluble matter (precipitate) or the like in the liquid medium during the incubation. The rare earth mineral separated from the mineralization agent is recovered by recovering the solid phase by a known solid-liquid separation means such as centrifugation and separating the mineralization agent using a surfactant or the like as necessary. Can be obtained. Moreover, a rare earth mineral can be obtained by drying and / or baking as needed.

  The firing step for crystallization can be performed based on known conditions for crystallizing a known amorphous compound. For example, the heating temperature can be 300 ° C. or higher and 1500 ° C. or lower. When the rare earth mineral is an inorganic salt such as carbonate, a heating temperature for crystallization while maintaining the state of the inorganic salt can be set. In the case where an oxide is obtained by desorbing an inorganic acid such as dehydration from a hydroxide or decarboxylation from a carbonate, the temperature at which the desorption occurs can be appropriately selected.

  Separation of rare earth ions by this mineralization agent is advantageous in that it can be realized under simple low-cost conditions. Moreover, it is advantageous in that particles of rare earth minerals at the nm level can be obtained by a mineralization agent.

  The rare earth mineral produced based on the mineralization ability of the present mineralization agent is produced as particles in which rare earth is detected. The generated rare earth mineral is presumed to be a rare earth hydroxide, a rare earth salt, or a rare earth oxide (or a hydrate thereof). The rare earth mineral produced may be crystalline or amorphous at the time of production. In the case of an amorphous material, it can be crystallized by performing a firing step as necessary.

(Rare earth ion detection method)
According to the present specification, a method for detecting rare earth ions is provided. The method for detecting rare earth ions includes a step of bringing a detection target that may contain ytterbium ions and / or lutetium ions into contact with a mineralization agent to be mineralized. According to this detection method, ytterbium ions and / or lutetium ions are separated as rare earth minerals. Furthermore, ytterbium ions and / or lutetium ions can be detected by providing a step of detecting the detected mineral or the rare earth species in the mineral.

  As described above, the method for separating rare earth ions can be implemented as a method for detecting rare earth ions by further including a rare earth mineral or a rare earth species detection step in the rare earth mineral. According to this detection method, it is possible to easily detect whether ytterbium ions and / or lutetium ions are contained in a detection target that may contain ytterbium ions and / or lutetium ions of a rare earth ion series. it can. In addition, the separation object in this separation method can be applied as the detection object in this detection method.

  In the detection process, the rare earth mineral produced by the mineralization agent is detected by a detection method based on the rare earth, and information for identification given to the mineralization agent (for example, on the labeling substance, beads, or array). Etc.) and a detection technique based on the mineralization agent such as an antibody that specifically binds to the mineralization agent.

  According to the present specification, the method for separating ytterbium ions and / or lutetium ions can be carried out as a method for mineralization of these ions and a method for producing a complex with rare earth ions. In this case, the separation target in this separation method can be used as a mineralization target and a composite target, respectively.

(Other)
In addition, according to this specification, DNAs, such as a nucleotide which codes this mineralization agent, the DNA construct for expressing such DNA as a peptide of a predetermined amino acid sequence, and the vector containing the said DNA are also provided. Such DNA acquisition and expression vector construction can be easily carried out by those skilled in the art by techniques well known in the art. The elements of the expression vector are selected according to the type of host cell for expressing the mineralization sequence of the mineralization agent and the DNA encoding the mineralization region.

  Moreover, according to this specification, the holding body hold | maintained this mineralization agent on a solid-phase carrier is also provided. This mineralization agent may be hold | maintained at the granular material, such as various beads, and the sheet-like body which consists of various materials, for example. Such solid phase carriers are known and can be appropriately selected and used by those skilled in the art. Such immobilization forms and techniques of peptides and the like on the surface of a solid phase carrier are known. A person skilled in the art can appropriately select an immobilization technique, select a desired form (such as an immobilization pattern on a sheet-like solid phase carrier), and obtain a peptide solid phase carrier. The particulate solid phase carrier can typically take a form in which the present peptide is held on the entire surface of the solid phase carrier by dipping or the like. Further, the sheet-like solid phase carrier can take a form in which the present peptide is held in a film form or in an arbitrary pattern by dipping, coating, spotting or the like. Such supports are useful as columns, beads and array devices for the separation and detection of ytterbium and / or lutetium ions.

  There is also provided a holder for holding the mineralization agent on a biological carrier. Specifically, the peptide having the mineralization sequence of the present mineralization agent may be in a state where the peptide is presented on the surface layer of a biological carrier such as a cell or in a state constituting the surface layer. Examples of biological carriers include various microorganisms, plant cells, animal cells, viruses and phages. The present mineralization agent, which is a peptide, may be displayed on the surface of a microorganism such as yeast or Escherichia coli, or may be configured as an outer shell protein in a phage or virus. Such a support is also useful as a device for separating and detecting ytterbium ions and / or lutetium ions.

  Hereinafter, the disclosure of this specification will be specifically described by way of examples. In addition, the following examples do not limit the present invention.

[Various peptide synthesis]
Peptide synthesis was performed by a solid-phase synthesis method using a 9-Fluorenylmethylcarbonyl (Fmoc) group. The N-terminus was biotinylated via Gly-Gly-Gly-Ser derived from the T7 phage g10 sequence. The peptide cleaved from the HMP (parahydroxymethylphenoxymethyl polystyrene) resin and deprotected was formed with intramolecular disulfide bonds by the iodine oxidation method, and then purified by reverse phase chromatography (Reverse phase HPLC). The purity of the peptide was confirmed using a mass spectrometer (HPLC / MS).

  Alanine substitution was performed on the amino acid sequence of the peptide consisting of the amino acid sequence represented by SEQ ID NO: 11 (referred to as Lamp-1) to synthesize peptides having 15 amino acid sequences. The amino acid sequences of the Lamp-1 and Lamp-1 alanine substitution products are shown in FIG.

[Evaluation of Mineralization Phenomenon of Synthetic Peptides]
The following lanthanoid nitrates (both SIGMA-Aldrich) were prepared with MES buffer (50 mM) to a final concentration of 3000 μM (pH 6.0). To this, the above synthetic peptide was added at a final concentration of 100 μM and reacted at room temperature. After the reaction, the absorbance (600 nm) of the mixed solution was measured for 15 minutes, 1 hour, and 18 hours. Absorbance without peptide was subtracted as a blank. The results for 15 minutes after the reaction are shown in FIG. Further, the results after 15 minutes, 1 hour and 18 hours after the reaction are shown in FIG.

Lanthanum nitrate hexahydrate La (NO ₃ ) ₃・ 6H ₂ O
Cerium nitrate hexahydrate Ce (NO ₃ ) ₃・ 6H ₂ O
Neodymium nitrate hexahydrate Nd (NO ₃ ) ₃・ 6H ₂ O
Samarium nitrate hexahydrate Sm (NO ₃ ) ₃・ 6H ₂ O
Europium nitrate hexahydrate Eu (NO ₃ ) ₃・ 6H ₂ O
Gadolinium nitrate hexahydrate Gd (NO ₃ ) ₃・ 6H ₂ O
Terbium nitrate hexahydrate Tb (NO ₃ ) ₃・ 6H ₂ O
Dysprosium nitrate hexahydrate Dy (NO ₃ ) ₃・ 6H ₂ O
Holmium nitrate pentahydrate Ho (NO ₃ ) ₃・ 5H ₂ O
Ytterbium nitrate pentahydrate Yb (NO ₃ ) ₃・ 5H ₂ O
Lutetium nitrate n-hydrate Lu (NO ₃ ) ₃・ nH ₂ O

  As shown in FIG. 2, a mutant peptide in which the fourth tryptophan (W) is replaced with alanine (A) (Ser-Cys-Leu-Ara-Gly-Asp-Val-Ser-Glu-Leu-Asp-Phe- In Leu-Cys-Ser), high mineralization reaction was observed only for ytterbium and lutetium ions, confirming that the mineralization selectivity was improved.

  Moreover, as shown in FIG. 3, the mutant peptide (Ser-Cys-Leu-Ara-Gly-Asp-Val-Ser-Glu-Leu-Asp-) in which the fourth tryptophan (W) is substituted with alanine (A) is used. In Phe-Leu-Cys-Ser), mineralization to other rare earth ions was not confirmed even 18 hours after the reaction.

[Gel filtration chromatography]
A Superdex peptide 10/300 column (GE healthcare) was set on AKTA purifier (GE healthcare), and various synthetic peptides (10 uM) were injected. TBS (Tris buffered saline; 50 mM Tris-HCl, 150 mM NaCl) adjusted to pH 6.8 was used as a running buffer, and the measurement was performed at a flow rate of 0.5 ml / min. Gel Filtration Standard (Bio-rad) was used as a molecular weight marker. The results are shown in FIG.

  As shown in FIG. 4, as a result of analysis by gel filtration, it was shown that some of the Lamp-1 alanine substitutes associate with each other to form a dimer. In general, it was found that the molecules forming the dimer tend to have low selectivity for Ln mineralization. Further, the substituted 4WA having improved selectivity to ytterbium ions and lutetium ions has a molecular weight smaller than that of Lamp-1, but as a result of gel filtration, the only apparent size (space occupied volume) becomes larger. It was shown that Substituting tryptophan (W) with alanine (A) results in the loss of bulky side chains, suggesting the possibility that the structural change of the whole peptide contributes to the improvement of selectivity.

(Evaluation of mineralization of other 4-position tryptophan substitutions)
In the same manner as in Example 1, a peptide (FIG. 5) was synthesized in which tryptophan (W) at position 4 in the amino acid sequence represented by SEQ ID NO: 11 was substituted with alanine and other various amino acids.

  About these peptides, the mineralization phenomenon was evaluated about various lanthanoid nitrates like Example 1. FIG. The results are shown in FIG.

  As shown in FIG. 6, in the mutant peptides (4WG, 4WS, 4WN) in which the fourth tryptophan (W) is substituted with glycine (G), serine (S), and asparagine (N), the fourth tryptophan (W ), A high mineralization reaction was observed only for ytterbium and lutetium as in the case where alanine (A) was substituted. On the other hand, those substituted with leucine (L), phenylalanine (F), and tyrosine (Y) (4WL, 4WF, 4WY) showed selectivity similar to Lamp-1.

  From the above, peptides with improved selectivity (4WA, 4WG, 4WS, 4WN) tend to have a significant decrease in the degree of hydrophobicity and side chain bulkiness of the fourth amino acid compared to Lamp-1. there were. Moreover, these results suggest that the nature of the side chain of the fourth amino acid contributes to the specificity of the mineralization target.

Sequence numbers 1-11: Synthetic peptide

Claims (11)

A mineralization agent of a rare earth species having an ability to capture rare earth species that are rare earth minerals and / or rare earth ions,
-X1-X2-X3-A1-X4-X5-A2-X6-A3-X7-X8-
(However, A1 to A3 are each independently an acidic amino acid, X1 is leucine, isoleucine, valine or threonine, X2 is alanine, glycine, serine or asparagine, and X3 is glycine, isoleucine, Cysteine, serine, arginine, X4 is valine, serine, arginine, methionine, phenylalanine or leucine, X5 is serine, leucine, arginine, glycine, cysteine, asparagine or lysine, and X6 is leucine, lysine, Valineserine or glycine, X7 is phenylalanine, glycine, leucine, threonine, isoleucine, valine, tryptophan or histidine, X8 is leucine, valine, threonine, serine, asparagine, phenylara Emissions, is a glutamic acid.)
An amino acid sequence represented by
A mineralization agent that captures ytterbium (Yb) and / or lutetium (Lu) as the rare earth species.   The amino acid sequence is represented by Leu-Ala / Gly / Ser / Asn-Gly-Asp / Glu-Val-Ser / Asn-Asp / Glu-Leu / Val-Asp / Glu-Phe / Leu-Leu, Item 2. The mineralization agent according to Item 1.   The ytterbium and / or lutetium is selectively captured with respect to any of gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), and erbium (Er). Mineralization agent.   The mineral sequence according to any one of claims 1 to 3, wherein the amino acid sequence is represented by Leu-Ala / Gly / Ser / Asn-Gly-Asp-Val-Ser-Glu-Leu-Asp-Phe-Leu. Zeation agent.   The mineralization agent in any one of Claims 1-4 which is a cyclic peptide containing the said amino acid sequence. The rare earth species mineralization agent according to any one of claims 1 to 5, and a separation object that may contain ytterbium (Yb) and / or lutetium (Lu) as a rare earth species that is a rare earth mineral and / or a rare earth ion A step of contacting
A method for separating rare earth species.   The method according to claim 6, wherein the rare earth species is ytterbium ion.   The method of claim 6, wherein the rare earth species is lutetium ion. A ytterbium (Yb) ion and / or a mineralization target that may contain lutetium (Lu) ion is contacted with the rare earth species mineralization agent according to any one of claims 1 to 5, to thereby provide ytterbium. Mineralizing ions and / or lutetium ions,
A mineralization method for rare earth ions. A detection target that may contain ytterbium (Yb) ion or lutetium (Lu) ion and the rare earth species mineralization agent according to any one of claims 1 to 5 are brought into contact with each other, and ytterbium ion or lutetium ion Detecting step,
A method for detecting rare earth ions. A complex object that may contain ytterbium (Yb) ion and / or lutetium (Lu) ion is contacted with the rare earth species mineralization agent according to any one of claims 1 to 5, and ytterbium ion And / or forming a complex of lutetium ion and peptide,
A method for producing a rare earth composite.