InterPro domain: IPR011837

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.

This entry represents the glycogen debranching enzyme GlgX found in Escherichia coli, as well as its equivalogs in other prokaryotic species. This enzyme encodes an isoamylase-type debranching enzyme with high specificity for hydrolysis of chains consisting of three or four glucose residues, and is classed as family 13 of glycosyl hydrolases [ 3 ]. GlgX is not required for glycogen biosynthesis, but instead acts as a debranching enzyme for glycogen catabolism. This entry distinguishes GlgX from pullanases and other related proteins that also operate on alpha-1,6-glycosidic linkages [ 4 ].

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. Role of the Escherichia coli glgX gene in glycogen metabolism. J. Bacteriol. 187, 1465-73
4. Coordinate genetic regulation of glycogen catabolism and biosynthesis in Escherichia coli via the CsrA gene product. J. Bacteriol. 178, 1012-7