Exploitation of beta-glycosyl azides for the preparation of alpha-glycosynthases,

An interesting approach for the chemo-enzymatic synthesis of carbohydrates is the use of glycosynthases, a class of mutant glycosidases derived from ?-glycoside hydrolases obtained by replacement of the active site nucleophile with a non-nucleophilic residue. However, the scarcity of ?-glycosynthases has so far hampered access to the synthesis of a large class of oligosaccharides of biotechnological interest. We review here a new glycosynthetic methodology for the production of two retaining ?-fucosynthases and an ?-galactosynthase exploiting ?-glycosyl azide derivatives. The general applicability of this approach, which opens new perspectives in the use of azide derivatives for the production of novel ?-glycosynthases, is discussed.