An Aminopeptidase from Bovine Brain Which Catalyzes the Hydrolysis of Enkephalin

An aminopeptidase from bovine brain which catalyzes the hydrolysis of the tyrosyl¹-glycine² bond of methionine⁵-enkephalin has been purified to electrophoretic homogeneity. The enzyme also catalyzes the hydrolysis of di-peptides, tripeptides, and amino acid β-naphthylamides. The enzyme can be inactivated by dialysis against EDTA, and reconstituted with divalent metal ions. Inhibition of the enzyme is observed in the presence of p-chloromercuribenzoate and puromycin, the latter compound not being hydro-lyzed by the enzyme. The enzyme is composed of a single polypeptide chain of molecular weight approx. 100,000. The properties of this enzyme are similar to those reported for other brain aminopeptidases active on enkephalin, although distinct differences are observed.