Primary Citation of Related Structures: 2JKA, 2JKE, 2JKP
PubMed Abstract:
Enzymatic cleavage of the glycosidic bond yields products in which the anomeric configuration is either retained or inverted. Each mechanism reflects the dispositions of the enzyme functional groups; a facet of which is essentially conserved in 113 glycoside hydrolase (GH) families ...
Enzymatic cleavage of the glycosidic bond yields products in which the anomeric configuration is either retained or inverted. Each mechanism reflects the dispositions of the enzyme functional groups; a facet of which is essentially conserved in 113 glycoside hydrolase (GH) families. We show that family GH97 has diverged significantly, as it contains both inverting and retaining alpha-glycosidases. This reflects evolution of the active center; a glutamate acts as a general base in inverting members, exemplified by Bacteroides thetaiotaomicron alpha-glucosidase BtGH97a, whereas an aspartate likely acts as a nucleophile in retaining members. The structure of BtGH97a and its complexes with inhibitors, coupled to kinetic analysis of active-site variants, reveals an unusual calcium ion dependence. 1H NMR analysis shows an inversion mechanism for BtGH97a, whereas another GH97 enzyme from B. thetaiotaomicron, BtGH97b, functions as a retaining alpha-galactosidase.
Organizational Affiliation:
York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York, YO10 5YW, UK. gloster@ysbl.york.ac.uk
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