Computational titration experiments have been performed on active site residues in the cellobiohydrolase Cel7B from Melanocarpus albomyces using long time constant pH molecular dynamics simulations. Results indicate that in the free enzyme there exist two dominant protonation schemes for the active site residues. These two highly dynamical protonation schemes, which oscillate between one another, are found to be conducive to substrate binding. In the presence of a bound substrate cellulose fragment, the protonation states of various active site residues converge to a protonation scheme that is indicative of the commonly proposed catalytic mechanism. This catalytically active protonation scheme is found to have a significant impact on the conformations adopted by the substrate sugar rings.

Dynamical protonation of catalytic residues in endocellulase Cel7B: Insights from constant pH molecular dynamics simulations

245th National Meeting (2013)

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