Oxidation of kynuramine by Lentil seedling copper amine oxidase: demonstrtion of a single turnover mechanismin the apoenzyme

Copper amine oxidase was shown to be able to oxidize kynuramine to the corresponding aldehyde, which spontaneously rearranged to 4-hydroxyquinoline. Under anaerobic conditions, the native enzyme oxidized one equivalent of kynuramine and released one equivalent of aldehyde per enzyme subunit. The apoenzyme gave exactly the same 1:1:1 stoichiometry under anaerobic as well as aerobic conditions. These findings demonstrate unequivocally that copper-free amine oxidase can oxidize substrates with a single incomplete turnover.