Silkworm Oligopeptide-4 is a single chain peptide containing 12 amino acids consisting of alanine, glycine, tyrosine and valine, obtained from the silkworm. The starting gene codes for Fibroin Heavy Chain, found in the silkworm. The parent protein contains a maximum of 5263 amino acids which may contain disulfide bonds and/or glycosylation, and consists of the proper sequence of the 20 standard amino acids.