Glycoside hydrolases and glycosyltransferases: families and functional modules.

The past year has witnessed the expected increase in the number of solved structures of glycoside hydrolases and glycosyltransferases, and their constitutive modules. These structures show that, while glycoside hydrolases display an extraordinary variety of folds, glycosyltransferases and carbohydrate-binding modules appear to belong to a much smaller number of folding families.