<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>Glycoside hydrolase family 37 <db_xref db="CAZY" dbkey="GH37"/> comprises enzymes with only one known activity; trehalase (<db_xref db="EC" dbkey="3.2.1.28"/>).</p><p>Trehalase is the enzyme responsible for the degradation of the disaccharide alpha,alpha-trehalose yielding two glucose subunits [<cite idref="PUB00002824"/>]. It is an enzyme found in a wide variety of organisms and whose sequence has been highly conserved throughout evolution.</p>