Abstract: The present invention relates to a modified fibroin including a domain sequence represented by Formula 1: [(A)nmotif-REP]m or Formula 2: [(A)nmotif-REP]m?(A)n motif, in which the domain sequence has an amino acid sequence with a reduced content of a glutamine residue equivalent to an amino acid in which one or a plurality of glutamine residues in REP are deleted or substituted with other amino acid residues, as compared with a naturally occurring fibroin.

Abstract: An object of the present invention is to provide a method capable of producing a protein fiber in which shrinkage at the time of first contact with moisture after production is more reliably suppressed and generation of crimp is also suppressed. A method for producing a protein fiber according to the present invention includes: a pre-shrinking step of shrinking a protein fibril in a relaxed state after drawing and before being wound; a winding step of winding the protein fibril subjected to the pre-shrinking step to obtain a wound product; and a post-shrinking step of shrinking the protein fibril subjected to the winding step in a relaxed state.

Abstract: An object of the present invention is to provide a method for advantageously producing a protein molded article which can solve a problem caused by esterification of a hydroxyl group contained in a protein while maintaining a sufficient strength. A method for producing a protein molded article according to the present invention includes a step of bringing a raw material molded article containing a protein in which a hydroxyl group is esterified into contact with an acidic or basic medium in a state of applying a tensile force, thus hydrolyzing an ester group.

Abstract: An object of the present invention is to provide a method for producing an artificial structural protein fiber having a small diameter and having a stress equal to or higher than that of the related art. A method for producing an artificial structural protein fiber according to the present invention is a method for producing an artificial structural protein fiber by a wet spinning method, the method including a coagulation step of discharging a spinning dope containing an artificial structural protein and an organic solvent from a spinneret into a coagulation liquid to coagulate the artificial structural protein, wherein a bath draft in the coagulation step is more than 0.4 and 20 or less.

Abstract: The present invention relates to a modified fibroin including a domain sequence represented by Formula 1: [(A)n motif-REP]m or Formula 2: [(A)n motif-REP]m-(A)n motif, and having a serine residue content rate of less than 5.5%. [In Formula 1 and Formula 2, the (A)n motif represents an amino acid sequence consisting of 4 to 27 amino acid residues, and the number of alanine residues with respect to the total number of amino acid residues in the (A)n motif is 80% or more. REP represents an amino acid sequence consisting of 10 to 200 amino acid residues. m represents an integer of 10 to 300. The plurality of (A)n motifs may be the same amino acid sequence or different amino acid sequences. A plurality of REPs may be the same amino acid sequence or different amino acid sequences.

Abstract: Disclosed is a fiber for artificial hairs that is given a predetermined shape, the fiber being formed from a synthetic fibroin fiber containing a modified fibroin, and the fiber expanding when placed in a wet state and contracting when dried from a wet state. Also disclosed is a method for producing a fiber for artificial hairs that is given a predetermined shape, the method including retaining a fibroin fiber containing a modified fibroin in a state conforming to a predetermined shape. A wetted fibroin fiber may also be heated while being retained in a state conforming to a predetermined shape.

Abstract: The present invention provides a modified fibroin fiber having a shrinkage history of being irreversibly shrunk after spinning, the modified fibroin fiber containing modified fibroin, wherein a fiber diameter of a raw material fiber before being irreversibly shrunk exceeds 25 ?m.

Abstract: An object of the present invention is to provide a method for producing a modified fibroin multifilament excellent in productivity and a multifilament produced by the same. The multifilament of the present invention contains modified fibroin, in which the multifilament has 100 or more constituent single yarns, a coefficient of variation in elastic modulus is 15% or less, a coefficient of variation in strength is 15% or less, and a coefficient of variation in elongation is less than 33%.

Abstract: Disclosed is a method for producing a protein fiber, the method including: bringing a spinning dope containing a protein and an organic solvent into contact with a coagulation liquid to coagulate the protein, wherein a content of the protein in the spinning dope is more than 10% by mass based on a total amount of the spinning dope, and the coagulation liquid contains water or an aqueous solution of pH 0.25 or more and pH 10.00 or less.

Abstract: A production method of a protein composition, the method comprising a step of hydrolyzing an ester group by bringing a raw material composition containing an esterified protein into contact with an acidic or basic medium.

Abstract: The present invention pertains to an artificial hair fiber that includes an artificial fibroin fiber containing a modified fibroin and that expands when being in a wet state and shrinks when being dried after the wet state.

Abstract: Provided is a side-by-side type composite fiber having a latent crimping ability, including a first component containing a modified fibroin and a second component containing a structural protein, in which the first component and the second component are joined to each other.

Abstract: The present invention relates to a method for manufacturing a protein fiber, the method including a step of bringing a spinning raw liquid containing a spider silk protein and a solvent into contact with a coagulation liquid to coagulate the spider silk protein, in which the coagulation liquid contains a ketone.

Abstract: An object of the present invention is to provide a method for efficiently manufacturing a protein crimped staple from protein filaments at a low cost. A manufacturing method for a protein crimped staple according to the present invention includes: a) preparing an artificial fibroin filament containing a modified fibroin; b) cutting the artificial fibroin filament to obtain an artificial fibroin staple; and c) performing crimping by bringing the artificial fibroin filament into contact with an aqueous medium to crimp the artificial fibroin filament before the cutting or bringing the artificial fibroin staple into contact with an aqueous medium to crimp the artificial fibroin staple after the cutting.

Abstract: The present invention relates to a modified fibroin including a domain sequence represented by Formula 1: [(A)n motif-REP]m or Formula 2: [(A)n motif-REP]m-(A)n motif, in which the domain sequence has an amino acid sequence with a reduced content of a glutamine residue equivalent to an amino acid in which one or a plurality of glutamine residues in REP are deleted or substituted with other amino acid residues, as compared with a naturally occurring fibroin. [In Formula 1 and Formula 2, (A)n motif represents an amino acid sequence consisting of 4 to 27 amino acid residues, and the number of alanine residues with respect to the total number of amino acid residues in the (A)n motif is 80% or more. REP represents an amino acid sequence consisting of 10 to 200 amino acid residues. m represents an integer of 10 to 300. A plurality of (A)n motifs may be the same amino acid sequence or different amino acid sequences.

Abstract: The present invention relates to a polypeptide solution in which polypeptide including an amino acid sequence derived from type I keratin that belongs to Cluster Ia is dissolved in a solvent including a formic acid or a solvent including an aprotic polar agent having a dipole moment of 3.0 D or more and an inorganic salt.