Further studies on aminopeptidases of rat muscle

Abstract

1. I. Four aminopeptidase peaks (pH 7.5) were obtained from rat muscle extract on DEAE Sephadex. 2. 2. All showed little or no inhibition with 1 mM puromycin. 3. 3. Peak II hydrolysed alanine 2-naphthylamide at a much faster rate than other 2-naphthylamides. Peak III hydrolysed arginine 2-naphthylamide, with little or no activity on lcucine- or alanine-2-naphthylamides. Peak IV had broad specificity, methionine 2-naphthylamide being most rapidly split. Peak IV but not II readily hydrolysed the 7-amino-4-methylcournarin derivative of alanine. 4. 4. Peak II and IV were inhibited by Cu 2+, Zn 2+ and Co 2+ (10 μm or less), and II by similar concentrations of Mn 2+. Peak II was inhibited by l mM Mg 2+ and stimulated by l mM Ca 2+. 5. 5. Molecular weights (gel filtration) were: II. 50,000; III. 66,000; IV, 309,000.