Time-resolved solid-state REDOR NMR studies of UDP N-acetylglucosamine enolpyruvyl transferase.

The new method of time-resolved solid-state rotational echo double resonance (REDOR) NMR spectroscopy introduced recently by this laboratory has been applied to the enzyme uridine N-acetylglucosamine (UDP-NAG) enolpyruvyl transferase (EPT), with the goal of probing the interactions between reactive species and their enzyme active site. The approach has been used in a qualitative fashion with the enzyme-inhibitor and enzyme-intermediate complexes of uniformly 15N-labeled UDP-NAG EPT, trapped under steady-state and pre-steady-state conditions. A different set of intermolecular interactions between the substrates UDP-NAG, UDP-NAG plus 3-Z-fluorophosphoenolpyruvate, covalent O-phosphothioketal, and UDP-NAG plus phosphoenolpyruvate trapped under time-resolved conditions (after 50 ms reaction time), and the EPT enzyme active site were observed, and this is contrasted to a similar study of the interactions in a related enzyme, 5-enolpyruvyl-shikimate-3-phosphate synthase.