glycosyl hydrolase family 16. The O-Glycosyl hydrolases 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 glycosyl hydrolase classification system based on sequence similarity has led to the definition of more than 95 different families inlcuding glycosyl hydrolase family 16. Family 16 includes lichenase, xyloglucan endotransglycosylase (XET), beta-agarase, kappa-carrageenase, endo-beta-1,3-glucanase, endo-beta-1,3-1,4-glucanase, and endo-beta-galactosidase, all of which have a conserved jelly roll fold with a deep active site channel harboring the catalytic residues.

Xyloglucan endo-transglycosylase (XET) C-terminus. This family represents the C-terminus (approximately 60 residues) of plant xyloglucan endo-transglycosylase (XET). Xyloglucan is the predominant hemicellulose in the cell walls of most dicotyledons. With cellulose, it forms a network that strengthens the cell wall. XET catalyzes the splitting of xyloglucan chains and the linking of the newly generated reducing end to the non-reducing end of another xyloglucan chain, thereby loosening the cell wall. Note that all family members contain the pfam00722 domain.

Glycosyl hydrolases family 16.

Probable xyloglucan endotransglucosylase/hydrolase protein; Provisional

Xyloglucan endotransglycosylase, member of glycosyl hydrolase family 16. Xyloglucan endotransglycosylases (XETs) cleave and religate xyloglucan polymers in plant cell walls via a transglycosylation mechanism. Xyloglucan is a soluble hemicellulose with a backbone of beta-1,4-linked glucose units, partially substituted with alpha-1,6-linked xylopyranose branches. It binds noncovalently to cellulose, cross-linking the adjacent cellulose microfibrils, giving it a key structural role as a matrix polymer. Therefore, XET plays an important role in all plant processes that require cell wall remodeling.