Abstract
Two aminopeptidases, I and II, were found in the acidic fraction of the yeast autolysate, adsorbed on DEAE-cellose and DEAE-Sephadex A-50. Aminopeptidase I was purified as a single protein with a molecular weight of 200, 000. The enzyme required Zn for its activity and hydrolyzed dipeptides, and a polypeptide (glucagon). It also hydrolyzed amides, naphthylamides and the p-nitroanilide of amino acids. The enzyme was strongly inhibited by sulfhydryl reagents. Aminopeptidase II seemed also to be a metal enzyme with a molecular weight of 34, 000. The enzyme hydrolyzed the dipeptide and tetrapeptide but not leucine p-nitroanilide.
