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), k_red, the oxidative half-reaction (oxidation of glucose oxidase by the mediator), k_ox and the maximum turnover number for glucose oxidase, k_o, have been obtained. k_ox was found to depend on the pH of the medium. At pH 7.0, A_ox for o-benzoquinone and p-benzoquinone are 6.0 × 10⁶ and 4.7 × 10⁵ mol^-1 dm³ s^-1, respectively. o-Benzoquinone appears to be a more effective electron transfer mediator than p-benzoquinone.