3-11: Stochastic simulations of action of enzyme cocktails on cellulose

We have developed a coarse-grained dynamical model that captures the key events associated with the enzymatic degradation of cellulose. The current model accounts for the mobility and action of a single enzyme as well as multiple enzymes on a homogeneous cellulose surface. Here, enzymes are tracked on a grid of substrate at the resolution of single glucose unit with explicit representation of chemical bonds. Cellulases are classified according to their activities with directionality and the effects of adsorption and processivity are implicitly accounted in the substrate through modification of the cellulose surface chemical and physical characteristics. The quantitative description of enzyme degradation is calculated in this spatial model by including free and bound states of all enzymes with explicit reactive surface terms and corresponding reaction rates. The dynamical evolution of the system is based on the physical interactions between enzymes and cellulose. We will present results that show the dependencies on enzyme ratios, enzyme loading and coverage for the degradation process. This model is capable of explaining the intrinsic stochastic properties due to cellulase adsorption/desorption and processivity on a cellulose surface and can be used to explain single molecule imaging and atomic force microscopy experiments on cellulases on cellulose. This work was supported in part by a LANL-LDRD grant under the auspices of the US Department of Energy.