title: Coordination chemical studies on metalloenzymes. Kinetics and mechanism of the Zn(II) exchange reaction between chelating agent and apo-bovine carbonic anhydrase.
abstract: The mechanism of removal of the zinc ion from bovine carbonic anhydrase [EC 4.2.1.1] (BCA) by a chelating agent was studied. It was shown that the removal of the zinc ion from BCA took place through the formation of a ternary complex involving the enzyme, chelating agent, and metal ions. The formation constant of the ternary complex (KEML) was 10(2) M-1. This value was lower than the formation constant assumed by Wilkins. The reaction of zinc-2, 6-pyridinedicarboxylate complex with the apoenzyme also took place through the formation of the ternary complex and the species which reacted with apo-BCA was a 1:1 complex of zinc and 2, 6-pyridine-dicarboxylate. The theoretical equilibrium equation derived from the reaction mechanism showed a good fit with observed equilibrium dialysis data.
mesh_terms: D000818:Animals; D001051:Apoenzymes / Q000378:metabolism; D002256:Carbonic Anhydrases / Q000378:metabolism*; D002417:Cattle; D003956:Dialysis; D003998:Dicarboxylic Acids / Q000494:pharmacology; D004912:Erythrocytes / Q000201:enzymology; D007700:Kinetics; D046911:Macromolecular Substances; D009994:Osmolar Concentration; D011485:Protein Binding; D011725:Pyridines / Q000494:pharmacology; D015032:Zinc / Q000494:pharmacology*
chemical_list: D001051:Apoenzymes; D003998:Dicarboxylic Acids; D046911:Macromolecular Substances; D011725:Pyridines; D002256:Carbonic Anhydrases; D015032:Zinc