Recent Advances in the Oligosaccharide Synthesis Promoted by Catalytically Engineered Glycosidases

In oligosaccharide synthesis the chemo-en- zymatic approach is often chosen to obtain the de- sired glycosidic bond by exploiting the exquisite sub- strate specificity and stereoselectivity of glycosidases and glycosyltransferases. In recent years the invention of new enzymatic activities, named glycosynthases, created a third route for the enzymatic synthesis of oligosaccharides. Glycosynthases are mutant glycosi- dases, devoid of hydrolytic activity, that produce oli- gosaccharides with yields > 80%. The glycosynthase technology is now well established and was greatly improved recently. Several groups experimentally proved that this methodology can be applied to sever- al glycosidases and that the activity of existing glyco- synthases can be significantly enhanced. In this review we briefly describe the characteristics of these syn- thetic tools and show a survey of the most recent find- ings. Methods for the prediction of the glycosynthetic potential of known glycosidases are also discussed.