在25K温度下进行魔角旋转的生物分子固态核磁共振。
Biomolecular solid state NMR with magic-angle spinning at 25K.
作者信息
Thurber Kent R, Tycko Robert
机构信息
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 5, Room 112, Bethesda, MD 20892-0520, USA.
出版信息
J Magn Reson. 2008 Dec;195(2):179-86. doi: 10.1016/j.jmr.2008.09.015. Epub 2008 Sep 23.
A magic-angle spinning (MAS) probe has been constructed which allows the sample to be cooled with helium, while the MAS bearing and drive gases are nitrogen. The sample can be cooled to 25K using roughly 3 L/h of liquid helium, while the 4-mm diameter rotor spins at 6.7 kHz with good stability (+/-5 Hz) for many hours. Proton decoupling fields up to at least 130 kHz can be applied. This helium-cooled MAS probe enables a variety of one-dimensional and two-dimensional NMR experiments on biomolecular solids and other materials at low temperatures, with signal-to-noise proportional to 1/T. We show examples of low-temperature (13)C NMR data for two biomolecular samples, namely the peptide Abeta(14-23) in the form of amyloid fibrils and the protein HP35 in frozen glycerol/water solution. Issues related to temperature calibration, spin-lattice relaxation at low temperatures, paramagnetic doping of frozen solutions, and (13)C MAS NMR linewidths are discussed.
已构建了一个魔角旋转（MAS）探头，它能在使用氮气作为MAS轴承和驱动气体的同时，用氦气冷却样品。使用约3 L/h的液氦可将样品冷却至25K，直径4 mm的转子以6.7 kHz的转速稳定旋转（±5 Hz）长达数小时。可施加高达至少130 kHz的质子去耦场。这种氦冷却MAS探头能够在低温下对生物分子固体和其他材料进行各种一维和二维核磁共振实验，信噪比与1/T成正比。我们展示了两个生物分子样品的低温（13）C NMR数据示例，即淀粉样原纤维形式的肽Abeta(14 - 23)和冷冻甘油/水溶液中的蛋白质HP35。讨论了与温度校准、低温下的自旋晶格弛豫、冷冻溶液的顺磁掺杂以及（13）C MAS NMR线宽相关的问题。
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