Degree of glucose conversion in amperometric glucose oxidase (-mutarotase) membrane electrodes

Abstract

The substrate concentration dependence of the peroxide flux to the amperometric glucose oxidase (-mutarotase) electrode and of the product accumulation in the bulk phase was studied at enzyme loadings between 0.046 and 46 Unit/cm 2 of glucose oxidase and 0 or 100 Unit/cm 2 of mutarotase. It is demonstrated that at low glucose oxidase loading the electrode process is controlled by the enzyme kinetics, while at excess of glucose oxidase the internal diffusion is the slowest step. In the absence of mutarotase only 63 % of glucose (the β-form) is converted because the spontaneous mutarotation is slow compared with the glucose oxidation. The consumption in bulk glucose concentration (about 0.2 % per min) is negligible during operation of the electrode.