sr-Sturgeon Polypeptide-4 is a single chain recombinant protein produced by fermentation in Pichia pastoris. The starting gene is synthesized to be identical to the gene which codes for Extracellular Superoxide Dismutase [Cu-Zn] derived from the sturgeon, Acipenser schrenckii. The parent protein contains a maximum of 243 amino acids which may contain disulfide bonds and/or glycosylation and consists of the proper sequence of the 20 standard amino acids.