RELEASE OF THE FAD DOMAIN FROM CELLOBIOSE OXIDASE BY PROTEASES FROM CELLULOLYTIC CULTURES OF PHANEROCHAETE-CHRYSOSPORIUM

Evidence has previously suggested that cellobiose:quinone oxidoreducta se (CBQ) in cellulolytic cultures of Phanerochaete chrysosporium might be produced from cellobiose oxidase (CBO) by proteolytic cleavage. Th is study demonstrates that the ratio of CBO activity to (CBO + CBQ) ac tivity declines with decreasing culture pH, while protease activity in creases. Furthermore, we demonstrate that endogenous P. chrysosporium proteases can only cleave CBO when the enzyme is bound to cellulose. T his is the first demonstration that the proteases produced in cellulol ytic cultures of P. chrysosporium can release the FAD domain from CBO.