Role of metal ions in goat carboxypeptidase A-catalysed hydrolysis of acyl peptides.
The carboxypeptidase A purified from goat pancreas has been found to have a molecular weight of 34,600 +/- 300. The enzyme is a zinc-protein and the molar ratio of zinc to enzyme protein is 1:1. Removal of zinc yields an inactive apocarboxypeptidase A. The loss of activity of the native enzyme and restoration of the activity of the apoenzyme run parallel with the zinc content of the protein, thus showing the essentiality of zinc for the enzymatic activity. The exact role of zinc in the enzyme catalysed hydrolysis of the acylpeptides has been investigated after preparing metallo proteins by substituting the zinc of carboxypeptidase A with Co2+, Mn2+, Ni2+, Fe2+, Cd2+, Hg2+, and Cu2+ and determining the kinetic parameters of such metalloproteins. These studies indicate that the metal ion is involved in both binding the substrate and polarising the peptide bond.
D000818:Animals; D002268:Carboxypeptidases / Q000378:metabolism*; D043422:Carboxypeptidases A; D002413:Cations, Divalent; D004151:Dipeptides; D004950:Esterases; D006041:Goats; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals / Q000494:pharmacology*; D010179:Pancreas / Q000201:enzymology*; D010455:Peptides; D013379:Substrate Specificity; D015032:Zinc / Q000494:pharmacology
D002413:Cations, Divalent; D004151:Dipeptides; D008670:Metals; D010455:Peptides; C019156:carbobenzoxyglycylphenylalanine; D004950:Esterases; D002268:Carboxypeptidases; D043422:Carboxypeptidases A; D015032:Zinc