Direct bioelectrocatalysis at electrodes modified with D-gluconate dehydrogenase.

D-Gluconate dehydrogenase isolated from Pseudomonas fluorescens was immobilized on the surfaces of carbon and gold electrodes by irreversible adsorption. The electrodes with the adsorbed enzyme produced anodic currents in solutions containing D-gluconate. The currents were attributable to the electro-enzymic oxidation (direct bioelectrocatalytic oxidation) of D-gluconate; the electrochemical system required no external redox molecules serving as mediators of electron transfer between the electrode and the adsorbed enzyme. A model of the direct bioelectrocatalysis at the enzyme-modified electrodes is presented.