Composite molding composition including fibroin-like protein, and method for producing composite molding composition

1. A composition comprising:

a fibroin-derived protein; and

a polyamino acid having a β-sheet structure, wherein

the polyamino acid consists of a homopolyamino acid or a copolymer of 2 to 5 kinds of amino acids.

2. The composition according to claim 1 ,

wherein the composition is a composite molding composition which is obtained by molding the fibroin-derived protein blended with the polyamino acid having the β-sheet structure.

3. The composition according to claim 2 ,

wherein the composite molding composition retains the β-sheet structure derived from the polyamino acid.

4. The composition according to claim 2 ,

wherein said composite molding composition is selected from a composite fiber, a composite film, a composite gel or a composite molded body.

5. A composite molding composition formed of a fibroin-derived protein blended with a polyamino acid having a β-sheet structure,

wherein the polyamino acid consists of a homopolyamino acid or a copolymer of 2 to 5 kinds of amino acids,

wherein the composite molding composition is selected from a composite fiber, a composite film and a composite gel, and is produced by a method comprising:

(i) preparing a dope solution in which the fibroin-derived protein and the polyamino acid having the β-sheet structure are dissolved; and

(ii) molding the composite molding composition from the dope solution.

6. A pre-drawn composite molding composition, being selected from a composite fiber or a composite film, and produced by a method comprising the processes (i) and (ii) according to claim 5 and

(iii) drawing the composite molding composition obtained in the process (ii) in a solvent and then drying the composite molding composition.

7. The composition according to claim 2 ,

wherein the fibroin-derived protein is selected from:

(i) a natural fibroin-derived protein; and/or

(ii) a modified fibroin-derived protein.

8. The composition according to claim 7 ,

wherein the natural fibroin-derived protein is at least one selected from the group consisting of a silk fibroin-derived silk protein (silk fibroin protein), a spider thread fibroin-derived spider thread protein (spider thread fibroin protein) and a hornet silk fibroin-derived hornet silk protein.

9. The composition according to claim 7 ,

wherein the modified fibroin-derived protein is a modified fibroin-derived protein having a domain sequence represented by the following formula (I):

[(A) m motif-REP] m   (I),

wherein as compared to a naturally derived fibroin, at least one or a plurality of the glycine residues in REP are substituted with a different amino acid residue(s), and the domain sequence has an amino acid sequence with a reduced content of glycine residues,

in the

in the (A)n motif, (A) represents an amino acid residue, n represents an integer of 8 to 20, and the number of alanine residues relative to a total number of the amino acid residues in the (A) n motif is 40% or more; and wherein the ratio of the number of alanine residues/the total number of the amino acid residues in the (A)n motif becomes maximum in the calculation;

REP represents an amino acid sequence consisting of 2 to 200 amino acid residues;

m represents an integer of 2 to 300;

the plurality of (A) n motifs may be the same amino acid sequences or different amino acid sequences; and

the plurality of REPs may be the same amino acid sequences or different amino acid sequences.

10. The composition according to claim 9 ,

wherein in the modified fibroin-derived protein, the domain sequence, as compared to a naturally derived fibroin, has an amino acid sequence equivalent to an amino acid sequence in which, in at least one motif sequence selected from GGX and GPGXX, wherein X represents an amino acid residue other than glycine, in REP, one glycine residue in said at least one motif sequence or a plurality of the motif sequences is substituted with a different amino acid residue(s); and

a ratio of the motif sequences in which the glycine residue is substituted with a different amino acid residue(s) is 10% or more with respect to all the motif sequences.

11. The composition according to claim 9 ,

wherein in the modified fibroin-derived protein, a maximum value of x/y (%) is 20% or more,

in which x represents a sum total of the numbers of amino acid residues in two adjacent [(A) n motif-REP] units, provided that, with the number of amino acid residues in REPs of two adjacent [(A) n motif-REP] units being sequentially compared from the N-terminal side to the

C-terminal side, when the number of amino acid residues in an REP having a smaller number of amino acid residues is defined as 1, a ratio of the number of amino acid residues in the other REP thereto becomes 2 to 3.5; and

y represents a total number of amino acid residues in the domain sequence.

12. The composition according to claim 9 ,

wherein the modified fibroin-derived protein represented by the formula (I) is a modified fibroin-derived protein having the amino acid sequence set forth in any one of SEQ ID NOs:4 to 19; or a sequence having a homology of 90% or more with respect to the amino acid sequence of any one of SEQ ID NOs:4 to 19.

13. The composition according to claim 12 ,

wherein the modified fibroin-derived protein has the sequence of any one of SEQ ID NOs:4 to 19.

14. The composition according to claim 2 ,

wherein the polyamino acid having the β-sheet structure is a polyalanine.

15. The composition according to claim 14 ,

wherein the polyalanine is selected from a linear polyalanine or a telechelic polyalanine.

16. The composition according to claim 1 ,

wherein the polyamino acid having the β-sheet structure has a polymerization degree of 5 to 50.

17. The composition according to claim 16 ,

wherein the compounding ratio of the polyamino acid having the β-sheet structure is in a range of 0.5 to 30.0%.

18. The composition according to claim 16 ,

wherein the compounding ratio of the polyamino acid having the β-sheet structure is in a range of 1 to 10.0%.

19. A composite molded body comprising the composition of claim 1 , said composite molded body being produced by a method comprising:

(i) preparing the composition by mixing the fibroin-derived protein and the polyamino acid having a β-sheet structure; and

(ii) heating the composition while applying a pressure thereto.

20. A method for producing a composite molding comprising the composition of claim 1 that is formed of the fibroin-derived protein blended with the polyamino acid having a β-sheet structure, and is selected from a composite fiber, a composite film and a composite gel, comprising:

(i) preparing a dope solution in which the fibroin-derived protein and the polyamino acid having the β-sheet structure are dissolved; and

(ii) producing the composition by performing spinning from the dope solution or further performing drawing.

21. A method for producing a pre-drawn composite molding composition, comprising:

(i) drawing, in a solvent, the composition produced by the method according to claim 20 ; and

(ii) drying the drawn composition.

22. The method according to claim 20 ,

wherein the fibroin-derived protein is selected from:

(i) a natural fibroin-derived protein; and/or

(ii) a modified fibroin-derived protein.

23. The method according to claim 22 ,

wherein the natural fibroin-derived protein is at least one selected from the group consisting of a silk fibroin-derived silk protein (silk fibroin protein), a spider thread fibroin-derived spider thread protein (spider thread fibroin protein) and a hornet silk fibroin-derived hornet silk protein.

24. The method according to claim 20 ,

wherein the polyamino acid having the β-sheet structure is a polyalanine.

25. The method according to claim 24 , wherein the polyalanine is selected from a linear polyalanine or a telechelic polyalanine.