Proteolytic preparation of a heme binding fragment from sperm whale myoglobin: Micro-myoglobin

Clostripain digestion of sperm whale apomyoglobin does not yield a heme bin ding fragment, contrary to horse heart apomyoglobin, from which mini-myoglo bin has been obtained by this approach. However, in pepsin digests of sperm whale apomyoglobin we identified two fragments closely corresponding to th e polypeptide encoded by the central exon of the myoglobin gene. One of the se fragments consisting of 77 amino acid residues was purified. Spectroscop ic data indicate that it has heme binding properties.