(64g) Changes of Cellulose Reactivity with Purified Enzyme Components during Hydrolysis

Yang, B., University of California Riverside
Shi, J., University of California, Riverside
Larenas, E., Genencor, A Danisco Divison
Mitchinson, C., Genencor International
Wyman, C. E., University of California, Riverside

To better understand the mechanism of enzymatic hydrolysis of cellulose, we applied a restart protocol to explore how cellulose reactivity changed and the interaction of cellulose with major cellulase components over the course of enzymatic hydrolysis. This approach allowed us to accurately monitor the hydrolysis rate of partially converted cellulose over the time course of substrate digestion excluding the impact of cellulase changes. In this presentation, the effect of enzyme-substrate interactions on reaction rates was studied using purified key cellulase components (i.e., CBHI, EGI, and/or EGII) from wild type Trichoderma reesei, and their synergism was studied by comparing the interrupted enzymatic hydrolysis of pure cellulose as measured using the restart protocol with uninterrupted hydrolysis as well as with the hydrolysis behavior of individual key cellulase components. Important chemical and physical features, including DP, reducing ends, crystallinity index, accessible surface area, and cellulose reactivity with enzymes, were characterized over the time course of cellulose hydrolysis, and the effects of cellulose reactivity and cellulase processivity on enzymatic hydrolysis of cellulose will be discussed.