Biocatalysis of Glucose 2-Oxidase from Coriolus Versicolor at High Pressures

摘要

Glucose 2-oxidase (pyranose oxidase, pyranose:oxygen-2-oxidoreductase, EC 1.1.3.10) from Coriolus versicolor catalyses the oxidation of D-glucose at carbon 2 in the presence of molecular oxygen producing D-glucosone (2-keto-glucose and D-arabino-2-hexosulose) and hydrogen peroxide. This enzyme was used to convert D-glucose into D-glucosone at high pressures with compressed air in a modified commercial batch reactor. Several parameters affecting biocatalysis at high pressures were investigated as follows: pressure, enzyme concentration, glucose concentration, supercritical fluid and the presence of catalase. Glucose 2-oxidase was purified by immobilized metal affinity chromatography on epoxy-activated Sepharose 6B-IDA-Cu(II) column at pH 6.0. The conversion of D-glucose into D-glucosone was dependent on the pressure since an increase in the pressure with compressed air resulted in higher rates of conversion. On the other hand, the presence of catalase increased the rate of reaction which strongly suggests that hydrogen peroxide inhibited the rate of reaction. The rate of conversion of D-glucose into D-glucosone by glucose 2-oxidase in the presence of either nitrogen or supercritical CO_2 at 110 bar was very low compared with the use of compressed air at the same pressure.