InterPro: IPR018221 Glycoside hydrolase, family 9, active site

O-Glycosyl hydrolases EC: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 [1, 2, 3]. This classification is available on the CAZy (CArbohydrate-Active EnZymes) web site [4]. Because the fold of proteins is better conserved than their sequences, some of the families can be grouped in clans.

Glycoside hydrolase family 9 GH9 comprises enzymes with several known activities; endoglucanase (EC:3.2.1.4); cellobiohydrolase (EC:3.2.1.91). These enzymes were formerly known as cellulase family E.

This entry contains two patterns that are centred on conserved residues which have been shown [5, 6], in the endoglucanase D from Cellulomonas thermocellum, to be important for the catalytic activity. The first region contains an active site histidine and the second region contains two catalytically important residues: an aspartate and a glutamate.