SEMINAR @ SISSA, SBP, Xevi Biarnes 07 Feb 2007

[Barbara Corzani]

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STATISTICAL AND BIOLOGICAL PHYSICS SEMINAR
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Dott. Xevi Biarnes
( Theoretical Chemistry Research Special Centre, Barcelona Science Parc)

Title:
"MECHANISMS OF SUBSTRATE PREACTIVATION IN ?-GLYCOSIDE HYDROLASES"

Wed 07 Feb 2007  @ 05.00 p.m.


SISSA - Basement floor - room C

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Abstract:

Glycoside Hydrolases (GHs) are responsible for the enzymatic cleavage of glycosidic bonds in polysaccharides. Recent experimental studies reveal that the substrate binds to these enzymes in a distorted conformation, and this is assumed to have important mechanistic implications. The
Michaelis complex structure of 1,3-1,4-?-glucanase, obtained from combined QM/MM calculations, will be presented. The distorted conformation adopted by the substrate is found to induce subtle structural and electronical rearrangements, which preactivate the
substrate for the catalytic reaction. A detailed description of the conformations of a single glucopyranose ring unit, using combined Car-Parrinello Molecular Dynamics and Metadynamics, will also be presented. Our calculations suggest that the factors governing the substrate distortions in GHs are largely dictated by the intrinsic properties of a single glucose unit.