Purification and Properties of an Aminopeptidase from Rabbit Skeletal Muscle

An aminopeptidase active on l-Val-l-Val-l-Val-l-Ala was purified from rabbit skeletal muscle by the method including ammonium sulfate precipitation, DEAE-cellulose chromatography, gel-filtration on Sephadex G–200, rechromatography on DEAE-cellulose, hydroxylapatite chromatography and rechromatography on Sephadex G–200. Polyacrylamide gel disc electrophoresis showed that the enzyme thus obtained was homogeneous. The specific activity of the purified enzyme was 1500 times that of the original muscle extract. The enzyme had an optimal pH in a range of 6.0~7.6 and was stable in pH 6.1~8.1. Molecular weight of the enzyme was estimated to be 160,000 from the result of gel-filtration on Sephadex G–200. The enzyme showed specificity for tri-, tetra-, penta-, and hexapeptides. The analytical data of liberated amino acids showed that the enzyme was an aminopeptidase active on these oligopeptides. The enzyme was strongly inhibited by N-ethyl-maleimide and EDTA.