Cellobiose dehydrogenase from Schizophyllum commune: purification and study of some catalytic, inactivation, and cellulose-binding properties.

Cellobiose dehydrogenase (CDH) of Schizophyllum commune was purified to homogeneity. It is a glycoprotein with a molecular mass of 102, 000. Cellulosic substrates can serve as substrates for CDH. Cytochrome c, dichlorophenol-indophenol, ferricyanide, and oxygen can be reduced by the enzyme. CDH is stable in the pH range of 4-11 and up to 35 degrees C. The enzyme keeps active at high concentrations of H2O2. In the presence of cellobiose and Fe3+, incubation of CDH resulted in its inactivation and the degree of the inactivation was dependent mainly on the amount of CDH and cellobiose present. CDH has a distinct and specific affinity to cellulose and showed the strongest binding to acid-treated cellulose. The adsorption isotherm data fitted the Langmuir-type equation. The uv-visible spectra of the oxidized and reduced states of CDH showed a typical cytochrome b-type pattern. Addition of dithionite eliminated the adsorption between 440 and 500 nm, which indicates the presence of a flavin group in CDH. Copyright 1998 Academic Press.