The tryptophan residue at the active site tunnel entrance of trichoderma reesei cellobiohydrolase Cel7A is Important for initiation of degradation of crystalline cellulose

Abstract

Background: Mutation of Trp-40 in the Cel7A cellobiohydrolase from Trichoderma reesei (TrCel7A) causes a loss of crystalline cellulose-degrading ability. Results: Mutant W40A showed reduced specific activity for crystalline cellulose and diffused the cellulose chain from the entrance of the active site tunnel. Conclusion: Trp-40 is essential for chain end loading to initiate processive hydrolysis of TrCel7A. Significance: The mechanisms of crystalline polysaccharide degradation are clarified. Copyright © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.