On the mechanism of immobilized glucose oxidase deactivation by hydrogen peroxide

Abstract

The result of experiments in a fixed-bed reactor containing glucose oxidase immobilized on a nonporous support and conducted in the absence of diffusional limitations are reported. Kinetic parameters were established by separate batch experiments. The key observation was that, in every case, poisoning by product hydrogen peroxide resulted in a minimum in enzyme activity in the interior of the bed, well away from the ends. The deactivation data were interpreted by fitting the rate constant for poisoning, the only free parameter, to a previously reported theory. The theory postulates several deactivation mechanisms each of which leads to self-consistent kinetics, but the only mechanism which fitted the data assumes that peroxide attack the enzyme when it is the from complexed with glucose. Theory and experiment agreed to within the accuracy (+/- 2%) of the activity measurements.