Bin Yang1, Charles E. Wyman1, and Colin Mitchinson2. (1) University of California, Center for Environmental Research and Technology, 1084 Columbia Avenue, Riverside, CA 92507, (2) Genencor, A Danisco Division, 925 Page Mill Road, Palo Alto, CA 94304
In order to develop better fundamental understanding of the mechanisms of enzymatic hydrolysis of cellulose, we explored how cellulose reactivity changes during enzymatic hydrolysis of cellulose and the relationship between major cellulase components and cellulose reactivity. In particular, our restart protocol, which was shown to be effective on pure cellulose hydrolysis, was applied to discern intermediate digestion and characteristics of reacted cellulose as the substrate reacted. In addition, the effect of enzyme-substrate interaction on reaction rates was studied using purified key cellulase components such as CBHI, CBHII, EGI, EGII, BG, and CBMs from wild type Trichoderma reesei. Enzyme synergism during interrupted enzymatic hydrolysis of pure cellulose with the restart protocol was compared with that during uninterrupted hydrolysis as well as with the hydrolysis behavior of the individual components. Important chemical and physical features, including accessible surface area, chemical moieties, chemical bonds, and cellulose reactivity with enzymes were characterized for each solid sample. Finally, a kinetic model was employed to clarify the effects of cellulose reactivity and cellulase processivity on enzymatic hydrolysis of cellulose.
