Studies on CytochromecOxidase, II. The Chemical Constitution of a Short Polypeptide from the Beef Heart Enzyme

Abstract
A low MW (.apprx. 6000) polypeptide fraction was isolated from beef heart cytochrome c oxidase, consisting of 3 peptides with the N-terminal end groups isoleucine, phenylalanine and serine. The complete amino acid sequence of the serine component is described. From the chemical constitution, a site-specific cleavage from a precursor protein and a possible function in membrane penetration and complex formation of the oxidase is inferred.