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Poster Presentation 6-40 Utility of Cellobiose Dehydrogenase in the Automated Measurement of Cellulolytic Activity
Stephen R. Decker, Edward W. Jennings, Todd B. Vinzant, William S. Adney and Michael E. Himmel
Biotechnology Division for Fuels and Chemicals National Renewable Energy Laboratory Golden, Colorado 80401
E-mail: steve_decker@nrel.gov
Cellobiose dehydrogenase (CDH) is produced by many white-rot fungi in response to growth on cellulosic biomass. Although its role in biomass degradation is unclear, it is well known to transfer electrons from cellobiose and short cello-oligomers to various acceptors, such as metal ions and organic cofactors. This electron transfer is mediated through both a heme group and a flavin group bound to the enzyme. Glucose is not oxidized and oxygen cannot be used as an acceptor. Additionally, CDH can transfer electrons to several artificial acceptors, including Dichlorophenolindophenol (DCIP). This dye changes color from blue to clear when reduced, allowing CDH activity to be measured directly. We have utilized CDH purified and characterized from Phanerochaete chrysosporium to quantify cellobiose equivalents produced during hydrolysis of cellulosic biomass with cellulase enzymes. This technique allows direct measurement of cellulase activity on real world substrates without the requirements of reducing sugar determination by HPLC or traditional colorimetric methods and may thus be well suited to automated analysis.
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