Glycogen debranching enzyme <p>O-Glycosyl hydrolases <db_xref db="EC" dbkey="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 [<cite idref="PUB00004870"/>, <cite idref="PUB00005266"/>]. This classification is available on the CAZy (CArbohydrate-Active EnZymes) web site.</p><p>This entry represents the glycogen debranching enzyme GlgX found in <taxon tax_id="562">Escherichia coli</taxon>, 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 [<cite idref="PUB00016734"/>]. 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 [<cite idref="PUB00015476"/>].</p><p>More information about this protein can be found at Protein of the Month: alpha-Amylase [<cite idref="PUB00027677"/>].</p>