Glycoside hydrolasesEC3.2.1. 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 glycoside hydrolases, based on sequence similarity, has led to the definition of >100 different families.[1][2][3] This classification is available on the CAZy web site,[4][5] and also discussed at CAZypedia, an online encyclopedia of carbohydrate active enzymes.[6][7]
Glycoside hydrolase family 39 CAZY GH_39 comprises enzymes with several known activities; alpha-L-iduronidase (EC3.2.1.76); beta-xylosidase (EC3.2.1.37).
The most highly conserved regions in these enzymes are located in their N-terminal sections. These contain a glutamic acid residue which, on the basis of similarities with other families of glycosyl hydrolases,[1] probably acts as the proton donor in their catalytic mechanism.