PETR 97 |
| The enzyme-catalyzed hydrolysis of cellulose in biomass involves two steps - reversible binding of the cellulase enzymes and catalytic bond-breaking - much like a Michaelis-Menten reaction. This process is complicated by the peculiar ways cellulose molecules assemble into the irregular fibrous networks of plant-cell walls. Only a small fraction of the cellulose is initially available for cellulase binding, and the accessibility changes as hydrolysis disassembles the cellulose network and makes new binding sites available. The overall hydrolysis rate for all times is a strong function of the initial cellulose microstructure, which is difficult to characterize. Electrospinning is a novel method for making structurally homogenous, pure cellulose fibers with independently variable diameter (d), degree of polymerization (DP), and crystallinity index (CrI). We are attempting to unravel the complicated relationship between cellulose microstructure and reaction rate by investigating the hydrolysis of electrospun cellulose by pure enzymes derived from Thermobifida fusca. We vary each microstructural property independently during electrospinning, and we measure its effect on hydrolysis kinetics. We use Cel5A, a prototypical endo-cellulase, and Cel6B, a prototypical exo-cellulase, to investigate independently the effects of polymer chain length and chain-end density on hydrolysis kinetics. In this presentation we describe the electrospinning method, present preliminary experimental results, and offer mechanistic interpretations. Keywords: cellulose, cellulase, biomass, hydrolysis, electrospinning |
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Symposium on Clean Fuels from Biomass
1:30 PM-5:15 PM, Tuesday, 12 September 2006 Palace -- Twin Peaks North, Oral
Division of Petroleum Chemistry |