Document Type

Article

Publication Date

3-18-1998

Journal or Book Title

Industrial and Engineering Chemistry Research

Volume

37

Issue

6

First Page

2148

Last Page

2157

DOI

10.1021/ie9706976

Abstract

Low-energy conformers of five α-(1,4)- and α-(1,6)-linked glucosyl trisaccharides were flexibly docked into the glucoamylase active site using AutoDock 2.2. To ensure that all significant conformational space was searched, the starting trisaccharide conformers for docking were all possible combinations of the corresponding disaccharide low-energy conformers. All docked trisaccharides occupied subsites −1 and +1 in very similar modes to those of corresponding nonreducing-end disaccharides. For linear substrates, full binding at subsite +2 occurred only when the substrate reducing end was α-(1,4)-linked, with hydrogen-bonding with the hydroxymethyl group being the only polar interaction there. Given the absence of other important interactions at this subsite, multiple substrate conformations are allowed. For the one docked branched substrate, steric hindrance in the α-(1,6)-glycosidic oxygen suggests that the active-site residues have to change position for hydrolysis to occur. Subsite +1 of the glucoamylase active site allows flexibility in binding but, at least inAspergillus glucoamylases, subsite +2 selectively binds substrates α-(1,4)-linked between subsites +1 and +2. Enzyme engineering to limit substrate flexibility at subsite +2 could improve glucoamylase industrial properties.

Comments

Posted with permission from Industrial & Engineering Chemistry Research, 37, no. 6 (1998): 2148–2157, doi:10.1021/ie9706976. Copyright 2012 American Chemical Society.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

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