Abstract: The present invention relates to a protein composition formed of dry matter of a dispersion in which a protein is dispersed in a stabilizer solution, in which the stabilizer includes at least one type selected from the group consisting of a catechol-based stabilizer, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid, 2,6-di-tert-butyl-p-cresol, 2-tert-butyl-4-methoxyphenol, and 6,6?-di-tert-butyl-4,4?-butylidenedi-m-cresol.

Abstract: The present invention relates to a modified fibroin including a domain sequence represented by Formula 1: [(A)n motif-REP]m, in which the domain sequence has an amino acid sequence locally containing a region with locally high hydropathy index equivalent to an amino acid sequence in which one or a plurality of amino acid residues in REP are substituted with amino acid residues with a high hydropathy index and/or one or a plurality of amino acid residues with a high hydropathy index are inserted into REP, as compared to naturally occurring fibroin. In Formula 1, (A)n motif represents an amino acid sequence consisting of 4 to 20 amino acid residues and the number of alanine residues relative to the total number of amino acid residues in the (A)n motif is 83% 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 and the like may be the same amino acid sequence or different amino acid sequences.

Abstract: Disclosed is a method for purifying a recombinant protein of interest from a recombinant cell expressing intracellularly the recombinant protein as an insoluble matter, comprising treating the recombinant cell under conditions where a protein derived from a host cell dissolves in a first aprotic polar solvent to which an inorganic salt is added or not but the recombinant protein does not dissolve, removing a first soluble fraction, and then treating the resulting first insoluble fraction under conditions where the recombinant protein dissolves in a second aprotic polar solvent to which an inorganic salt is added.

Abstract: The present invention provides a method for producing a molded article including a step 1 of adding water to a composition including a structural protein, a step 2 of molding a water-containing composition obtained in the step 1, and a step 3 of drying the molded composition obtained in the step 2 to obtain the molded article.

Abstract: The invention relates to a method for production of a recombinant protein using recombinant cells that express the recombinant protein under the control of an inducible promoter, the method including continuous culturing with addition of fresh culture medium to a portion of the culture solution in which the recombinant cells have been grown, wherein the recombinant cells whose expression of the recombinant protein has been induced are not reused.

Abstract: A film of the present invention contains a polypeptide derived from spider silk proteins. The decomposition temperature of the film is 240 to 260° C. The film absorbs ultraviolet light having a wavelength of 200 to 300 nm and has a light transmittance of 85% or more at a wavelength of 400 to 780 nm. The film is transparent and colorless in a visible light region. A method for producing a film of the present invention includes: dissolving a polypeptide derived from spider silk proteins in a dimethyl sulfoxide solvent to prepare a dope; and cast-molding the dope on a surface of a base. Thus, the present invention provides a spider silk protein film that can be formed easily and has favorable stretchability, and a method for producing the same.

Abstract: Provided are a composite molding composition such as a composite film and a composite fiber that have properties such as an improved tensile strength, strain and toughness as a result of blending a peptide or polyamino acid having a ?-sheet structure with a natural or artificially modified fibroin-derived protein; a method for producing such composite molding composition; and a method for improving the physical properties of a composite molding composition containing a fibroin-derived protein.

Abstract: An object of the present invention is to provide a method for efficiently separating insoluble bodies of a recombinant protein from a recombinant cell expressing a target recombinant protein as insoluble bodies in the cell. The present invention provides a method for producing a recombinant protein aggregate by separating insoluble bodies of a recombinant protein from a recombinant cell expressing the recombinant protein as insoluble bodies in the cell, including disrupting the recombinant cell, aggregating the insoluble bodies of the recombinant protein, and separating the resulting aggregate.

Abstract: Provided is a modified fibroin, including a domain sequence represented by Formula 1: [(A)n motif-REP]m, in which the domain sequence has an amino acid sequence having a reduced content of glycine residues equivalent to an amino acid sequence in which, at least, one or a plurality of the glycine residues in REP is substituted with another amino acid residue, as compared to naturally occurring fibroin: [In Formula 1, (A)n motif represents an amino acid sequence consisting of 4 to 20 amino acid residues and the number of alanine residues relative to the total number of amino acid residues in the (A)n motif is 83% or more, REP represents an amino acid sequence consisting of 10 to 200 amino acid residues, m represents an integer of 8 to 300, and a plurality of (A)n motifs or the like may be the same amino acid sequence or different amino acid sequences.

Abstract: Provided is a modified fibroin, including a domain sequence represented by Formula 1: [(A)n motif-REP]m, in which the domain sequence has an amino acid sequence having a reduced content of (A)n motif equivalent to an amino acid sequence in which, at least, one or a plurality of the (A)n motifs is deleted, as compared to naturally occurring fibroin. [In Formula 1, (A)n motif represents an amino acid sequence consisting of 4 to 20 amino acid residues and the number of alanine residues relative to the total number of amino acid residues in the (A)n motif is 83% or more, REP represents an amino acid sequence consisting of 10 to 200 amino acid residues, m represents an integer of 8 to 300, and a plurality of (A)n motifs or the like may be the same amino acid sequence or different amino acid sequences.

Abstract: Provided is a molded article of a composition comprising a polypeptide, wherein the polypeptide is at least one kind selected from the group consisting of natural spider silk protein and polypeptides derived from natural spider silk protein.

Abstract: The present invention provides, in one aspect, a method for producing a molded article, the method comprising exposing a molded article precursor comprising a protein to an environment with a relative humidity of 80% or more to obtain the molded article.

Abstract: The present invention provides, in one aspect, a method for producing a molded article, the method comprising exposing a molded article precursor comprising a protein to an environment with a relative humidity of 90% or more to obtain the molded article.

Abstract: The present invention relates to a method for producing a polymer aggregate, the method including: a step for bringing a polymer solution containing a polymer substance and cations for gel formation into contact with an anion solution containing anions for gel formation to form a gel at an interface between the polymer solution and the anion solution; and a step for causing the polymer substance to aggregate inside the gel.

Abstract: Provided is a method for producing a protein solution, including applying a pressure to a dispersion liquid containing a protein and a polar solvent in which the protein is dispersed, to obtain a protein solution containing the protein and the polar solvent in which the protein is dissolved.

Abstract: A method for producing a fibroin-like protein is provided. A fibroin-like protein is produced by a method of culturing Escherichia coli having a gene encoding the fibroin-like protein in a medium, inducing expression of the gene encoding the fibroin-like protein, and collecting the fibroin-like protein, wherein accumulation of an organic acid at the time of inducing the expression is reduced, and wherein the gene is expressed under control of a tryptophan promoter.

Abstract: Provided is a molded article of a composition comprising a polypeptide which has more than 4.3 GPa of a bending elastic modulus and transparency.

Abstract: A polypeptide porous body of the present invention is a porous body of a polypeptide derived from spider silk proteins. The polypeptide includes a water-insoluble polypeptide. The polypeptide porous body has an apparent density of 0.1 g/cm3 or less. A method for producing the polypeptide porous body includes: a solution production step in which the polypeptide is dissolved in at least one solvent selected from DMSO, DMF, and these with an inorganic salt, so as to obtain a solution of the polypeptide; a step in which the solution produced in the solution production step is substituted with a water-soluble solvent so as to obtain a polypeptide gel; and a step in which the polypeptide gel is dried. Thereby, the present invention provides a polypeptide porous body having excellent water absorbability and a polypeptide porous body suitable for application to a living body, and a method for producing the same.

Abstract: A polypeptide hydrogel of the present invention is a hydrogel of a polypeptide derived from spider silk proteins, and has a moisture content of 85.0 to 99.9 mass % based on 100 mass % of the polypeptide hydrogel. A method for producing the hydrogel includes: a solution production step in which a polypeptide derived from spider silk proteins is dissolved in at least one dissolving solvent selected from the group consisting of: (A) dimethyl sulfoxide; (B) dimethyl sulfoxide with an inorganic salt; and (C) N, N-dimethylformamide with an inorganic salt, so as to obtain a solution of the polypeptide; and a substitution step in which the solution produced in the solution production step is substituted with a water-soluble solvent. Thus, the present invention provides a polypeptide hydrogel having excellent water retentivity and a polypeptide hydrogel suitable for application to a living body.

Abstract: A method for producing a fibroin-like protein is described. A fibroin-like protein is produced by culturing Escherichia coli having a gene encoding the fibroin-like protein in a medium, inducing expression of the gene encoding the fibroin-like protein, and collecting the fibroin-like protein, wherein the accumulation of an organic acid at the time of inducing the expression is reduced.