Human placental dipeptidyl aminopeptidase III: hydrolysis of enkephalins and its stimulation by cobaltous ion |
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| Authors: | Y Shimamori Y Watanabe Y Fujimoto |
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| Institution: | Department of Clinical Biochemistry, Hokkaido Institute of Pharmaceutical Sciences, Japan. |
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| Abstract: | The degradation of enkephalin and related peptides by highly purified dipeptidyl aminopeptidase III (EC 3.4.14.4) was studied. The enzyme releases the N-terminal dipeptide units from substrates greater in length than the tetrapeptide. The enzyme exhibits an optimum of pH 7.5, Km of 81 microM and Vmax of 0.043 mumole/min for Leu-enkephalin. Its activity was markedly stimulated by Co2+, with both the Km and Vmax being increased. Among the enkephalin-related peptides examined, des-Tyr1-Leu-enkephalin was the most rapidly hydrolyzed with Co2+, but only slight stimulation was observed with Co2+. |
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