Document Type

Article

Publication Date

11-2-2009

Journal or Book Title

Carbohydrate Research

Volume

344

Issue

16

First Page

2157

Last Page

2166

DOI

10.1016/j.carres.2009.08.011

Abstract

Patterns of scissile bond twisting have been found in crystal structures of glycoside hydrolases (GHs) that are complexed with substrates and inhibitors. To estimate the increased potential energy in the substrates that results from this twisting, we have plotted torsion angles for the scissile bonds on hybrid Quantum Mechanics::Molecular Mechanics energy surfaces. Eight such maps were constructed, including one for α-maltose and three for different forms of methyl α-acarviosinide to provide energies for twisting of α-(1,4) glycosidic bonds. Maps were also made for β-thiocellobiose and for three β-cellobiose conformers having different glycon ring shapes to model distortions of β-(1,4) glycosidic bonds. Different GH families twist scissile glycosidic bonds differently, increasing their potential energies from 0.5 to 9.5 kcal/mol. In general, the direction of twisting of the glycosidic bond away from the conformation of lowest intramolecular energy correlates with the position (syn or anti) of the proton donor with respect to the glycon’s ring oxygen atom. This correlation suggests that glycosidic bond distortion is important for the optimal orientation of one of the glycosidic oxygen lone pairs toward the enzyme’s proton donor.

Comments

This is a post-print of an article from Carbohydrate Research, 344, no. 16 (2 November 2009): 2157–2166, doi: 10.1016/j.carres.2009.08.011.

Copyright Owner

Elsevier Ltd.

Language

en

File Format

application/pdf

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