<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>Glycoside hydrolase family 3 <db_xref db="CAZY" dbkey="GH3"/> comprises enzymes with a number of known activities; beta-glucosidase (<db_xref db="EC" dbkey="3.2.1.21"/>); beta-xylosidase (<db_xref db="EC" dbkey="3.2.1.37"/>); N-acetyl beta-glucosaminidase (<db_xref db="EC" dbkey="3.2.1.52"/>); glucan beta-1,3-glucosidase (<db_xref db="EC" dbkey="3.2.1.58"/>); cellodextrinase (<db_xref db="EC" dbkey="3.2.1.74"/>); exo-1,3-1,4-glucanase (<db_xref db="EC" dbkey="3.2.1"/>). These enzymes are two-domain globular proteins that are N-glycosylated at three sites [<cite idref="PUB00005846"/>]. This domain is often N-terminal to the glycoside hydrolase family 3, C-terminal domain <db_xref db="INTERPRO" dbkey="IPR002772"/>.<p>The signature pattern in these enzymes is centred on a conserved aspartic acid residue which has been shown [<cite idref="PUB00000578"/>], in <taxon tax_id="5066">Aspergillus wentii</taxon> beta-glucosidase A3, to be implicated in the catalytic mechanism. </p> Glycoside hydrolase, family 3, active site