InterPro: IPR005195 Glycoside hydrolase family 65, central catalytic

O-Glycosyl hydrolases EC: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, 3]. This classification is available on the CAZy (CArbohydrate-Active EnZymes) web site [4]. Because the fold of proteins is better conserved than their sequences, some of the families can be grouped in clans.

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 catalyzes 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 nucelophilic attack on the anomeric carbon atom [5]. The catalytic domain also forms the majority of the dimerisation interface.