Glycoside hydrolases: Mechanisms, specificities, and engineering

The diversity of oligosaccharides, polysaccharides, and glycoconjugates in nature is mirrored by the vast array of carbohydrate-active enzymes involved in their biosynthesis, degradation, and modification. Glycoside hydrolases (GHs or glycosidases) catalyze the cleavage of glycosidic bonds leading to hydrolysis products with retention or inversion of the anomeric configuration. They are classified in more than 170 GH families that cover the diversity of substrate specificities. Glycosidases are a prominent class of enzymes with many industrial, biomedical, and biotechnological applications. This chapter summarizes the main aspects of their catalytic mechanisms and the engineering of their properties as hydrolytic enzymes, as well as their applications as synthetic enzymes for glycoside bond formation as engineered transglycosylases and glycosynthases.