InterPro domain: IPR006101

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.

Glycoside hydrolase 2 GH2 comprises enzymes with several known activities; beta-galactosidase ( 3.2.1.23 ); beta-mannosidase ( 3.2.1.25 ); beta-glucuronidase ( 3.2.1.31 ).

These enzymes contain a conserved glutamic acid residue which has been shown [ 3 ], in Escherichia coli lacZ ( P00722 ), to be the general acid/base catalyst in the active site of the enzyme.

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. Glu-537, not Glu-461, is the nucleophile in the active site of (lac Z) beta-galactosidase from Escherichia coli. J. Biol. Chem. 267, 11126-30