Glycosidases configuration

Inhibition of configuration-retaining glycosidases by lactones, piperidines, and tetrazoles 99AG(E)750. 

T. D. Heightman, A T. Vasella, Recent Insights into Inhibition, Structure, and Mechanism of Configuration-Retaining Glycosidases , Angew. Chem. Int. Ed. 1999, 38,750-770. 

The same holds for substitution at C3 and C5 of the fructofuranose moiety of sucrose neither melezitose (XV)61 nor o-D-glucopyranosyl-/3-D-xyloketofuranoside (XVIc)22 is hydrolyzed by yeast saccharase. As might have been expected from the experience with glycosidases, any change in the configuration of the fructon of sucrose results in stereoisomers unhydrolyzable by /3-fructofuranosidase. Thus, methyl and benzyl a-D-fructofuranosides,62 isosucrose (= /3-D-glucopyranosyl-a-D-fructo-... 

Scheme 4.9 Models for the transition state of glycosidase (A)- and glycosyltransferase (B)-catalyzed reactions with inversion of the configuration.

Figure 7.28 Cleavage of the glycosidic bond by a glycosidase with inversion of configuration. Inhibition by 5-fluoroglycosyl fluoride. ...

Competitive inhibition of a-D-mannosidase is very well illustrated by the action of D-mannono-l,5-Iactone. /3-D-Glycosidases are powerfully and selectively inhibited by the aldono-1,5-lactones of configuration corresponding to that of the sugar residue in the substrate, and the effect is always competitive. In certain instances, of which a-D-mannosidase is one, inhibition extends to the a-D-glycosidase (see Ref. 69). 

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