Cellobiose Dehydrogenase fromSchizophyllum commune:Purification and Study of Some Catalytic, Inactivation, and Cellulose-Binding Properties

Cellobiose dehydrogenase (CDH) ofSchizophyllum communewas 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°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.