Abstract: The polyphenoloxidase has been isolated from banana peel by extraction with cold acetone. The catechol oxidation reaction catalyzed by polyphenoloxidase is selected as a model to study the oxidase catalyzed oxidation by using an oxygen electrode,The activation energy of the reaction was calculated to be 23. 6kJ·mol^-1,and the Michae's constant 1·58?10^-2mol/L. Nine compounds were found to have inhibition effects on the activity of the oxidase,The inhibition kinetics and the mechanism of the catechol oxidation have been investigated by using benzoic acid as inhibitor. The results showed that the copper ions which was found in the polyphenoloxidase may activate the substrates and the combination of the copper ions with inhibitor results in the inhibition effect on the catalytic oxidation.

Key words: catechol, polyphenoloxidase, inhibition, kinetics, mechanism, benzoic acid