How Thiamine Diphosphate Is Activated in Enzymes

• DOI: 10.1126/science.275.5296.67
• Publication Date: 2002-07-27T09:50:14Z
• Authors: Dorothee Kern; Gunther Kern; Holger Neef; Kai Tittmann; Margrit Killenber...; Christer Wikner; Gunter Schneider; Gerhard Hübner
• Keywords: Transketolase; Carbanion

The controversial question of how thiamine diphosphate, the biologically active form vitamin B 1 , is activated in different enzymes has been addressed. Activation coenzyme was studied by measuring thermodynamics and kinetics deprotonation at carbon 2-position (C2) diphosphate pyruvate decarboxylase transketolase use nuclear magnetic resonance spectroscopy, proton/deuterium exchange, analogs, site-specific mutant enzymes. Interaction a glutamate with nitrogen 1′-position pyrimidine ring 4′-amino group to act as an efficient proton acceptor for C2 proton. protein component accelerated atom several orders magnitude, beyond rate overall enzyme reaction. Therefore, earlier proposed concerted mechanism or stabilization carbanion can be excluded.