InterPro domain: IPR005195

O-Glycosyl hydrolases ( 3.2.1. ) are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycosyl hydrolases, based on sequence similarity, has led to the definition of 85 different families [ 1 , 2 ]. This classification is available on the CAZy (CArbohydrate-Active EnZymes) website.

The family of glycosyl hydrolases ( GH65 ) which contains this domain includes vacuolar acid trehalase and maltose phosphorylase. Maltose phosphorylase (MP) is a dimeric enzyme that catalyses the conversion of maltose and inorganic phosphate into beta-D-glucose-1-phosphate and glucose. The central domain is the catalytic domain, which binds a phosphate ion that is proximal the the highly conserved Glu. The arrangement of the phosphate and the glutamate is thought to cause nucleophilic attack on the anomeric carbon atom [ 3 ]. The catalytic domain also forms the majority of the dimerisation interface.

1. Conserved catalytic machinery and the prediction of a common fold for several families of glycosyl hydrolases. Proc. Natl. Acad. Sci. U.S.A. 92, 7090-4
2. Structures and mechanisms of glycosyl hydrolases. Structure 3, 853-9
3. Crystal structure of maltose phosphorylase from Lactobacillus brevis: unexpected evolutionary relationship with glucoamylases. Structure 9, 689-97