Xyloglucan endotranglucosylation (XET) activity

Xyloglucan transglycosylase / hydrolase (XTH) enzymes can have two different activities; xyloglucan endotransglucosylation (XET), and xyloglucan hydrolysis (XEH). The XET activity is represented in the picture. XTH can cleave a xyloglucan strand that bridges between two cellulose microfibrils(a), after which the strand with the non-reducing end is released while the enzyme remaines attached to the other strand (b). The enzyme can then connect the cleavage product with a non-reducing end of another xyloglucan strand (c). This way, load-bearing xyloglucan strands can be broken without loosing the overall integrity of the plant cell wall. In contrast to the XET activity, XEH activity hydrolyses xyloglucan strands, producing both non-reducing and reducing ends.