ROLE OF CELLULOSE-BINDING DOMAIN OF CELLOBIOHYDROLASE-I IN CELLULOSE HYDROLYSIS

The kinetics of the cellulose-binding domain's ability to adsorb onto microcrystalline cellulose (Avicel) and its effects on the surface structure of the cellulose fibers were studied. The catalytic domain of Trichoderma reesei cellobiohydrolase I was rendered inactive by modification with a water-soluble carbodiimide. After modification, the cellobiohydrolase I possessed no ability to hydrolyze the model substrate p-nitrophenyl-beta-D-cellobioside (PNPC). However, the modified cellobiohydrolase I was still capable of adsorbing onto microcrystalline cellulose. Scanning electron microscopy showed that whereas native CBH I smoothed the surface of cotton fibers, catalytically inactivated CBH I was without effect.