IS CELLOBIOSE OXIDASE FROM PHANEROCHAETE-CHRYSOSPORIUM A ONE-ELECTRON REDUCTASE

The heme domain of cellobiose oxidase (CBO) from Phanerochaete chrysosporium increases the rate of electron transfer to one-electron acceptors. This conclusion was drawn from comparisons of the rates of reduction of 3,5-t-butyl-o-benzoquinone, triiodide ion, cytochrome c and ferricyanide by intact CBO, FAD fragment and CBO with the heme inactivated by cyanide. The oxidation of cellobiose produced hydrogen peroxide, but the enzyme disturbs peroxidase-based assays by reduction of the product or by direct interaction with the peroxidase. CBO can also degrade hydrogen peroxide in the presence of cellobiose. The 1,2,4,5-tetramethoxybenzene cation radical was rapidly reduced by CBO.