Enzymatic Oxidation and Separation of Various Saccharides with Immobilized Glucose Oxidase

Abstract

Glucose oxidase from Aspergillus niger, the specific enzyme for beta-D-glucose oxidation, can also oxidize other related saccharides at very slow or negligible rates. The present study aimed to compare the kinetics of D-glucose oxidation using immobilized glucose oxidase on bead cellulose for the oxidation of related saccharides using the same biocatalyst. The significant differences were observed between the reaction rates for D-glucose and other saccharides examined. As a result, k (cat)/K (M) ratio for D-glucose was determined to be 42 times higher than D-mannose, 61.6 times higher than D-galactose, 279 times higher than D-xylose, and 254 times higher than for D-fructose and D-cellobiose. On the basis of these differences, the ability of immobilized glucose oxidase to remove D-glucose from D-cellobiose, D-glucose from D-xylose, and D-xylose from D-lyxose was examined. Immobilized catalase on Eupergit and mixed with immobilized glucose oxidase on bead cellulose or co-immobilized with glucose oxidase on bead cellulose was used for elimination of hydrogen peroxide from the reaction mixture. The accelerated elimination of D-glucose and D-xylose in the presence of co-immobilized catalase was observed. The co-immobilized glucose oxidase and catalase were able to decrease D-glucose or D-xylose content to 0-0.005% of their initial concentrations, while a minimum decrease of low oxidized saccharides D-xylose, D-cellobiose, and D-lyxose, respectively, was observed.