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 9 CAZY GH_9 comprises enzymes with several known activities including endoglucanase (EC3.2.1.4) and cellobiohydrolase (EC3.2.1.91). These enzymes were formerly known as cellulase family E. Cellulases (Endoglucanases) EC3.2.1.4 catalyse the endohydrolysis of 1,4-beta-D-glucosidic linkages in cellulose. GH9 family members have also been found in green microalgae (Chlamydomonas, Gonium and Volvox) that show highest sequence identity to endogenous GH9 cellulases from invertebrate metazoans [8][9]