Purification and Characterization of Aminopeptidase B from Escherichia coli K-12(Microbiology & Fermentation Technology)

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Aminopeptidase B, which is one of the four cysteinylglycinases of Escherichia coli K-12, was purified to electrophoretic homogeneity and its enzymatic characteristics were observed. Aminopeptidase B was activated by various divalent cations such as Ni^<2+>, Mn^<2+>, Co^<2+>, and Cd^<2+>, and lost its activity completely on dialysis against EDTA. This indicates that aminopeptidsase B is a metallopeptidase. It was stabilized against heat in the presence of Mn^<2+> or Co^<2+>. The activity of aminopeptidase B, which was saturated with one of above divalent cations, was enhanced on the addition of a very small amount of a second divalent cation. α-Glutamyl p-nitroanilide, leucine p-nitroanilide, and methionine p-nitroanilide were good substrates for aminopeptidase B, while native peptides, cysteinylglycine and leucylglycine, were far better substrates. The k_<cat>/K_m for cysteinylglycine was much bigger than those for leucylglycine or leucine p-nitroanilide.
社団法人日本農芸化学会の論文
2001-07-23