Purification and characterization of aminopeptidase activity from rat urine

The aminopeptidase activity of rat urine was tested using L-aminoacyl-2-naphthylamides and L-Leu-p-nitroanilide. The enzyme preparation was purified by ion-exchange and gel filtration chromatography and showed only a single active protein band on 7.5% polyacrylamide gel electrophoresis. The enzyme was characterized by studying the effects of ions (divalent cations and chloride), chelating agents and -SH and -S-S- group reagents and by determining kinetic parameters (Km and Vmax for different substrates and Ki for amino acids, antibiotics and anti-inflammatory drugs).