title: Human placental dipeptidyl aminopeptidase III: hydrolysis of enkephalins and its stimulation by cobaltous ion.
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+.
authors.affiliation: Department of Clinical Biochemistry, Hokkaido Institute of Pharmaceutical Sciences, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Shimamori
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Y
authors.initials: Y
authors.lastname: Fujimoto
mesh_terms: D002413:Cations, Divalent; D003035:Cobalt / Q000494:pharmacology*; D003600:Cytosol / Q000201:enzymology; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism*; D004745:Enkephalins / Q000378:metabolism*; D005260:Female; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D009842:Oligopeptides / Q000378:metabolism; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D013379:Substrate Specificity
chemical_list: D002413:Cations, Divalent; D004745:Enkephalins; D009842:Oligopeptides; D003035:Cobalt; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C100152:dipeptidyl peptidase III; C018021:cobaltous chloride