Details

Autor(en) / Beteiligte

• Young, Robert P
• Caulkins, Bethany G
• Borchardt, Dan
• Bulloch, Daryl N
• Larive, Cynthia K
• Dunn, Michael F
• Mueller, Leonard J

Titel

Solution-State 17OQuadrupole Central-Transition NMR Spectroscopy in the Active Site of Tryptophan Synthase

Ist Teil von

• Angewandte Chemie, 2016-01, Vol.128 (4), p.1372

Ort / Verlag

Weinheim: Wiley Subscription Services, Inc

Erscheinungsjahr

2016

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• Oxygen is an essential participant in the acid-base chemistry that takes place within many enzyme active sites, yet has remained virtually silent as a probe in NMR spectroscopy. Here, we demonstrate the first use of solution-state 17Oquadrupole central-transition NMR spectroscopy to characterize enzymatic intermediates under conditions of active catalysis. In the 143kDa pyridoxal-5'-phosphate-dependent enzyme tryptophan synthase, reactions of the [alpha]-aminoacrylate intermediate with the nucleophiles indoline and 2-aminophenol correlate with an upfield shift of the substrate carboxylate oxygen resonances. First principles calculations suggest that the increased shieldings for these quinonoid intermediates result from the net increase in the charge density of the substrate-cofactor π-bonding network, particularly at the adjacent [alpha]-carbon site.