Kinetics of o-Benzoquinone Mediated Oxidation of Glucose by Glucose Oxidase at Edge Plane Pyrolytic Graphite Electrode

The kinetic constants for the electrocatalytic oxidation of β-D-glucose by glucose oxidase in the presence of o- and p-benzoquinone as electron mediators have been evaluated by cyclic voltammetry in pH 6-8. The rate constants for the reductive half-reaction (reduction of glucose oxidase by β-D-glucose), kred, the oxidative half-reaction (oxidation of glucose oxidase by the mediator), koxand the maximum turnover number for glucose oxidase, ko, have been obtained. koxwas found to depend on the pH of the medium. At pH 7.0, Aoxfor o-benzoquinone and p-benzoquinone are 6.0 × 106and 4.7 × 105mol-1dm3s-1, respectively. o-Benzoquinone appears to be a more effective electron transfer mediator than p-benzoquinone.