n. (context biochemistry English) The main hemicellulose in the primary cell wall of dicotyledonous plants
Xyloglucan is a hemicellulose that occurs in the primary cell wall of all vascular plants; however, essential enzymes for xyloglucan metabolism, like XTH and β1→4-Glucan Synthase are found in Charophyceae algae. In many dicotyledonous plants, it is the most abundant hemicellulose in the primary cell wall. Xyloglucan binds to the surface of cellulose microfibrils and may link them together. It is the substrate of xyloglucan endotransglycosylase, which cuts and ligates xyloglucans, as a means of integrating new xyloglucans into the cell wall. It is also thought to be the substrate of alpha- expansin, which promotes cell wall enlargement.