A kinetic study of an amperometric enzyme electrode based on immobilised cytochrome C peroxidase

Abstract

Results are presented for the detection of hydrogen peroxide and m-chloroperbenzoic acid at an amperometric enzyme electrode based on cytochrome c peroxidase immobilised on a nylon membrane held in close proximity to the working electrode. Using 1,3'-dimethylferrocene ethylamine as a homogeneous mediator the enzyme substrate could be detected at −100 mV vs. SCE in buffered aqueous solution. A general model for the mass transport and kinetics of species within the enzyme membrane is presented and used to analyse the data. The results of this analysis show that the saturated electrode response is determined, either by the kinetics of the reaction of the substrate with the immobilised enzyme or by the reaction of the mediator with immobilised enzyme, depending upon the concentration of mediator employed. The relative rates of reaction of the two substrates, hydrogen peroxide and m-chloroperbenzoic acid, are found to be similar to those observed for the homogeneous enzyme.