Department of Physics, University of Warwick, Coventry, United Kingdom.
Phys Chem Chem Phys. 2011 Jul 14;13(26):12213-24. doi: 10.1039/c1cp20629j. Epub 2011 May 20.
Monosodium L-glutamate monohydrate, a multiple oxygen site (eight) compound, is used to demonstrate that a combination of high-resolution solid-state NMR spectroscopic techniques opens up new possibilities for (17)O as a nuclear probe of biomolecules. Eight oxygen sites have been resolved by double rotation (DOR) and multiple quantum (MQ) NMR experiments, despite the (17)O chemical shifts lying within a narrow shift range of <50 ppm. (17)O DOR NMR not only provides high sensitivity and spectral resolution, but also allows a complete set of the NMR parameters (chemical shift anisotropy and electric-field gradient) to be determined from the DOR spinning-sideband manifold. These (17)O NMR parameters provide an important multi-parameter comparison with the results from the quantum chemical NMR calculations, and enable unambiguous oxygen-site assignment and allow the hydrogen positions to be refined in the crystal lattice. The difference in sensitivity between DOR and MQ NMR experiments of oxygen in bio/organic molecules is also discussed. The data presented here clearly illustrates that a high resolution (17)O solid-state NMR methodology is now available for the study of biomolecules, offering new opportunities for resolving structural information and hence new molecular insights.
一水合谷氨酸单钠，一种多氧位（八个）化合物，被用于证明高分辨率固态 NMR 光谱技术的结合为（17）O 作为生物分子的核探针开辟了新的可能性。尽管（17）O 化学位移在 <50 ppm 的狭窄范围内，但通过双旋转（DOR）和多量子（MQ）NMR 实验已经分辨出了八个氧位。（17）O DOR NMR 不仅提供了高灵敏度和光谱分辨率，而且还允许从 DOR 旋转边带谱中确定一组完整的 NMR 参数（化学位移各向异性和电场梯度）。这些（17）O NMR 参数与量子化学 NMR 计算的结果提供了重要的多参数比较，并能够明确氧位分配，并允许在晶格中细化氢位。还讨论了生物/有机分子中氧的 DOR 和 MQ NMR 实验之间的灵敏度差异。这里呈现的数据清楚地表明，现在可用于研究生物分子的高分辨率（17）O 固态 NMR 方法已经可用，为解析结构信息并因此提供新的分子见解提供了新的机会。
