Engineering glycosidases for constructive purposes

The synthesis of oligosaccharides using glycosidases as catalysts has been known formany years, but has been limited by the poor yields generally associated with such processes due to hydrolysis. Glycosynthases, mutant glycosidases in which the catalytic nucleophile has been replaced, offer an alternative form of catalyst that synthesizes glycosides from readily prepared glycosyl fluorides, but does not hydrolyze the glycoside products. The range of reactions performed by these enzymes is being extended through mutation of number of different glycosidases, as well as through random mutation of known glycosynthases, coupled with efficient screens.