Some properties of leucine aminopeptidase from Aspergillus japonica as a metalloenzyme.

摘要: Some properties of purified leucine aminopeptidase [E.C. 3.4.1.1] from Aspergillus japonica as a metalloenzyme were investigated. Leucine was inhibited by various chelating agents. The addition Zn2+ to the ethylenediaminetetraacetic acid (EDTA)-treated restored activity nearly original level, but Co2+ partially effective. Kinetic studies using L-leucyl-β-naphthylamide substrate carried out with native aminopeptidase, or Co2+-reactivated after dialysis against EDTA. Michaelis constant (Km) and activation energy (Eact) in good agreement those reactivated (native Km : 2.5×10-4 M, Eact 9.2×103 cal/mol, Zn2+-reactivated 9.8×103 cal/mol). In presence L-leucyl-β-naphthylamide, inhibition agents Cd2+ decreased an extent 23-46%. Metal analysis indicated that containing 1 g-atom zinc per mol both content lowered when treated EDTA o-phenanthroline.