Kinetic Study of Direct Bioelectrocatalysis of Dioxygen Reduction with Bilirubin Oxidase at Carbon Electrodes

Abstract

Direct electron transfer-type bioelectrocatalysis of four-electron reduction of dioxygen was successfully realized with bilirubin oxidase (BOD, EC 1.3.3.5, from Myrothecium verrucaria) at carbon electrode surfaces with high crystal graphite edge density. It was found that adsorbed BOD functions as a biocatalyst. The current-potential curves were interpreted by considering the enzyme catalytic constant, surface electron transfer kinetics, surface concentration of BOD, and the formal potential of BOD. The analysis suggested that the standard surface electron transfer rate constant and surface coverage of “active” enzyme depend strongly on functional groups and/or nano-structure of carbon electrode surface.