J. Am. Chem. Soc., ASAP Article 10.1021/ja062031l S0002-7863(06)02031-2
Web Release Date: May 26, 2006
New Limits for Solid-State 17O NMR Spectroscopy: Complete Resolution of Multiple Oxygen Sites in a Simple Biomolecule
Alan Wong, Andy P. Howes, Kevin J. Pike, Vincent Lemaître, Anthony Watts, Tiit Anupõld, Jaan Past, Ago Samoson, Ray Dupree,* and Mark E. Smith*
Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom, Biochemistry Department, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom, and National Institute for Chemical Physics and Biophysics, Akadeemia Tee 23, Tallinn, Estonia
A solid-state 17O NMR 1H-decoupled double angle rotation (DOR) study of monosodium L-glutamate monohydrate (L-MSG) is reported. It is shown that all eight inequivalent sites can be resolved with DOR line widths (~65 Hz) ~120 times narrower than those in the MAS spectrum. The lines are tentatively assigned on the basis of their behavior under proton decoupling and the isotropic chemical shift and the quadrupole interaction parameter for each extracted by a combination of DOR and 3Q MAS at variable magnetic fields. With a shift range of ~45 ppm for these similar oxygen sites and spectral resolution under DOR comparable to that for spin-1/2 nuclei, solid-state 17O NMR should have tremendous potential in the study of biomolecules.