Ping-pong character of nasturtium-seed xyloglucan endotransglycosylase (XET) reaction.
Plant xyloglucan endotransglycosylase (XET, EC 2.4.1.207) degrades its substrate by a transglycosylation mechanism while endo-cleaving xyloglucan (XG) molecules at their beta-1,4-linked polyglucosyl main chain and transferring the newly generated reducing chain ends to hydroxyls at C-4 of non-reducing glucosyl ends of the main chains of other XG molecules or of low-Mr XG-fragments (OS). Kinetic data obtained with purified nasturtium seed (Tropaeolum majus, L.) XET while using high-Mr xyloglucan and 3H-labeled XGOS alditols (DP 7-9) as substrates could be best fitted to the model for Ping-Pong Bi Bi reaction mechanism. Such mechanism is typical for transglycosylases operating with retention of the anomeric configuration of the formed glycosidic bond and involving the formation of a covalent glycosyl-enzyme reaction intermediate.
Baran
R
R
Institute of Chemistry, Slovak Academy of Sciences, Bratislava.
Sulová
Z
Z
Stratilová
E
E
Farkas
V
V
D016695:Glycosyltransferases / Q000378:metabolism*; D007700:Kinetics; D008962:Models, Theoretical; D019685:Rosales / Q000201:enzymology*; D012639:Seeds / Q000201:enzymology*
D016695:Glycosyltransferases; C073693:xyloglucan endotransglycosylase