Patent ID: 8642734

Claim:
A method of producing polymers of an isolated spider silk protein, comprising the steps of: (i) providing a spider silk protein consisting of from 170 to 760 amino acid residues and comprising: an N-terminal (NT) fragment consisting of at least one fragment of from 100 to 160 amino acid residues derived from the N-terminal fragment of a spider silk protein; and a repetitive fragment of from 70 to 300 amino acid residues derived from the repetitive fragment of a spider silk protein; and optionally a C-terminal (CT) fragment of from 70 to 120 amino acid residues, which fragment is derived from the C-terminal fragment of a spider silk protein; (ii) providing a solution of said spider silk protein in a liquid medium at pH 6.4 or higher and/or an ion composition that prevents polymerisation of said spider silk protein, optionally involving removal of lipopolysaccharides and other pyrogens; (iii) adjusting the properties of said liquid medium to a pH of 6.3 or lower and an ion composition that allows polymerisation of said spider silk protein; (iv) allowing the spider silk protein to form polymers in the liquid medium, said liquid medium having a pH of 6.3 or lower and an ion composition that allows polymerisation of said spider silk protein; and (v) isolating the spider silk protein polymers from said liquid medium.