Multiple rewards from a treasure trove of novel glycoside hydrolase and polysaccharide lyase structures: new folds, mechanistic details, and evolutionary relationships

Recent progress in three-dimensional structure analyses of glycoside hydrolases (GHs) and polysaccharide lyases (PLs), the historically relevant enzyme classes involved in the cleavage of glycosidic bonds of carbohydrates and glycoconjugates, is reviewed. To date, about 80% and 95% of the GH and PL families, respectively, have a representative crystal structure. New structures have been determined for enzymes acting on plant cell wall polysaccharides, sphingolipids, blood group antigens, milk oligosaccharides, N-glycans, oral biofilms and dietary seaweeds. Some GH enzymes have very unique catalytic residues such as the Asp-His dyad. New methods such as high-speed atomic force microscopy and computational simulation have opened up a path to investigate both the dynamics and the detailed molecular interactions displayed by these enzymes.