Enzymatic Degradation of Cellulose
The ever increasing worldwide demands for energy, along with uncertain petroleum sources and the possibility of global climate change, has dictated the necessity for our nation to develop a sustainable and renewable alternative to fossil transportation fuel. Biofuels derived from lignocellulosic biomass are attractive alternatives due to the vast infrastructure already in place for the distribution of a liquid transportation fuel, and the fact that fuel derived from cellulose does not compete with human and livestock food resources. Furthermore, since cellulose is the most abundant renewable biopolymer on earth the feedstock for cellulosic biofuels is almost inexhaustible, and the utilization of cellulose for liquid fuel can achieve zero net carbon dioxide emission thereby making it a crucial component in our efforts to reduce green house gases.
Cellulosic biofuels are created by hydrolyzing cellulose to glucose and
subsequently fermenting the glucose to make biofuel. Several major obstacles
remain with regard to the viability of cellulosic biofuels including overcoming
natural resistance of cellulose to enzymatic depolymerization, known as
biomass recalcitrance, which is primarily responsible for the high cost of
cellulosic biofuels. To formulate ways to overcome biomass recalcitrance, a
basic understanding of the substrate and enzymes involved in the hydrolysis of
cellulose are needed. The enzymatic driven hydrolysis of crystalline cellulose
to glucose is regulated by three different cellulases: endocellulase (EG),
exocellulase (cellobiohydrolase, CBHI and CBHII), and β-glucosidase (BG).
The goal of my group’s proposed research is to model each of the three enzymes and evaluate their ability to bind substrate and catalyze the hydrolysis reaction. These simulations will utilize and develop novel methodologies so that the tools of statistical mechanics may be used to evaluate the underlying physics driving the enzyme substrate interactions and the catalytic reaction. These studies will provide insights into the enzyme systems and open new possibilities to engineering more efficient enzymes. Through collaborations with experimentalists and engineers these possible routes for enzyme improvement may be tested in vitro and subsequently implemented directly into test reactors (in vivo). The information gained from the in silico, in vitro, and in vivo experiments will then be used in the next generation bioreactors which will provide our nation with a renewable liquid transportation fuel alternative.