Adsorption and activity of Trichoderma reesei cellobiohydrolase I, endoglucanase II, and the corresponding core proteins on steam pretreated willow

The adsorption and the hydrolytic action of purified cellulases of Trichode rma reesei, namely, cellobiohydrolase I(CBH I), endoglucanase II (EG II), a nd their core proteins, on steam-pretreated willow were compared. The two e nzymes differed clearly in their adsorption and hydrolytic behavior. CBH I required the cellulose-binding domain (CBD) for efficient adsorption and hy drolysis, whereas EG II was able to adsorb to steam pretreated willow witho ut its CBD. Absence of the CBD decreased the hydrolysis of cellulose by EG II, but the decrease was less pronounced than with CBH I. A linear relation ship was observed between the amount of enzyme adsorbed and the degree of h ydrolysis of cellulose only for CBH I. EG II and EG II core appeared to be able to hydrolyze only 1 to 2% of the substrate regardless of the amount of protein adsorbed.