Isolation and partial characterization of bovine liver aminopeptidase B

Abstract

Aminopeptidase B, specifically hydrolyzing the L-lysine and L-arginine derivatives of p-nitroaniline and β-naphthylamine, was isolated from bovine liver. A multistep purification procedure involving fractionation with ammonium sulfate, gel filtration on Sephadex, ion exchange chromatography on Ecteola-cellulose, and adsorption chromatography on hydroxylapatite, afforded an enzyme whose activity was approximately 240 times higher than the activity of the original material. The molecular weight of the enzyme determined by gel filtration on Sephadex G-200 was approximately 55 000. The Michaelis constant with respect to L-lysyl-p-nitroanilide was 1.2 . 10-3 mol/l.