Formation and partial characterization of glucose-2-oxidase, a H2O2 producing enzyme in Phanerochaete chrysosporium

A sugar oxidizing enzyme which produces H2O2 during glucose starvation in the white-rot fungus Phanerochaete chrysosporium has been purified from mycelial extracts and somewhat characterized. Enzyme purity was confirmed by analytical isoelectric focusing and by dodecylsulfate/polyacrylamide gel electrophoresis, both techniques revealing a homogeneous protein. The enzyme is active over a broad pH range with maximum activity at pH 7.5. Of several sugars tested, glucose was the preferred substrate although δ-d-gluconolactone and d-xylose were also oxidized at significant rates (at 60% and 37%, respectively, of the rate observed with glucose). Km-values for glucose and xylose are 1.03 and 20 mM respectively and the glucose oxidation product was idenitified as d-arabino-2-hexosulose. The possible importance of glucose-2-oxidase in lignin degradation is discussed.