|HILDEBRAND, AMANDA - University Of California
|ADDISON, J. - University Of California
|FAN, ZHILIANG - University Of California
Submitted to: Biochemical Engineering Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2016
Publication Date: 5/15/2016
Citation: Hildebrand, A., Addison, J.B., Kasuga, T., Fan, Z. 2016. Cellobionic acid inhibition of cellobiohydrolase I and cellobiose dehydrogenase. Biochemical Engineering Journal. 109: 236-242. DOI: 10.1016/j.bej.2016.01.024.
Interpretive Summary: Both plant pathogenic fungi and oomycetes produce cellulases to degrade plant cell wall materials. Cellobiose, the main product of cellulases will then be converted to cellobionate by the action of cellobiose dehydrogenase (CDH). In this report, we investigated the mechanisms of catalytic inhibition of cellulases and CDH by their products and explored the optimization of decomposition of lignocellulosic biomass by plant pathogens for the production of fermentable sugars and biofuels.
Technical Abstract: End-product inhibition by cellobiose and glucose is a rate-limiting factor in cellulose hydrolysis by cellulases. While cellobiose and glucose inhibition have been extensively investigated, cellobionate inhibition has been minimally studied despite the discovery that accessory proteins such as cellobiose dehydrogenase (CDH) work synergistically with cellulases to form aldonic acids. The fraction of equilibrated cellobionate in the cellobiono-d-lactone form was determined by NMR over the range of pH 4-8. To better improve the understanding of cellobiono-d-lactone and cellobionate inhibition of cellulases, we investigate the inhibition of Trichoderma reesei cellobiohydrolase I, one of the most extensively studied CBHs, and Neurospora crassa CDH by equilibrated cellobionate. The well-characterized inhibitor cellobiose is evaluated in parallel for comparison. The mechanisms of inhibition are determined for both inhibitors and the kinetic parameters compared using a Michaelis-Menten inhibition model. Cellobiose and cellobionate inhibition of cellobiohydrolase I is extended to Avicel hydrolysis, along with an investigation of those inhibitors on Accelerase 1500, a commercial cellulase preparation.