Pichia Pastoris Extract/sr-(Sturgeon Polypeptide-4 Hexapeptide-40) is a single chain recombinant peptide, produced by fermentation in Pichia pastoris. The starting gene is synthesized by the fusion of the gene from sr-Sturgeon Polypeptide-4and Hexapeptide-40. The fusion peptide contains 251 amino acids which may contain disulfide bonds and/or glycosylation, and consists of the proper sequence of the 20 standard amino acids.