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Development of Solid State NMR Methods and Technology

固态核磁共振方法和技术的发展

基本信息

批准号：
7734021
负责人：
ROBERT TYCKO
金额：
$ 22.64万
依托单位：
NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

项目摘要

Progress in FY2008 was made in the following areas: (1) ULTRA-LOW-TEMPERATURE SOLID STATE NMR: Nearly all solid state NMR studies of interesting systems are limited by signal detection sensitivity. The sensitivity (i.e., signal-to-noise ratio) of solid state NMR measurements increases with decreasing sample temperature, approximately as 1/T1.5. Therefore, in principle, measurements at 30 K have thirty-fold higher sensitivity than measurements at room temperature, meaning that the time to complete a measurement can be reduced by a factor of 30 X 30 = 900 by operating at 30 K (since signal-to-noise is proportional to the square root of measurement time) if sample size is fixed. Alternatively, sample size requirements can be reduced by a factor of thirty. For these reasons, it is important to develop new solid state NMR technology for ultra-low-temperature measurements. In FY2008, we have succeeded in developing, testing, and applying a solid state NMR probe (which means the device that contains the sample and radiofrequency circuitry within the magnet of an NMR spectrometer) that operates at 25 K, with full capabilities for modern solid state NMR measurements. Capabilities include magic-angle spinning at 7 kHz and radio-frequency field strengths up to 140 kHz on the 1H channel, and greater than 50 kHz on the 13C channel, and liquid helium consumption less than 3 liters per hour. We have acquired experimental NMR data for several types of protein samples, including the helical protein HP35 in frozen solution, amyloid fibrils formed by residues 14-23 of the beta-amyloid peptide, and residues 1-40 of the HIV-1 Vpu transmembrane protein, in phospholipid bilayers. We have carried out two-dimensional 13C NMR measurements on these samples, as well as 13C-13C dipolar recoupling measurements on the amyloid sample. Other applications are now in progress.

2008财年在以下方面取得了进展： (1)超低温固体核磁共振：几乎所有感兴趣的体系的固体核磁共振研究都受到信号检测灵敏度的限制。固体核磁共振测量的灵敏度(即信噪比)随着样品温度的降低而增加，大约为1/T1.5。因此，原则上，30K下的测量灵敏度比室温下的测量高30倍，这意味着如果样本大小固定，在30K下工作可以将完成测量的时间减少30×30=900倍(因为信噪比与测量时间的平方根成正比)。或者，样本量要求可以减少到原来的1/30。因此，开发新的固体核磁共振技术用于超低温测量是非常重要的。2008财年，我们成功地开发、测试和应用了一种固态核磁共振探头(即在核磁共振光谱仪的磁铁中包含样品和射频电路的设备)，该探头工作在25K，具备现代固态核磁共振测量的全部能力。功能包括以7 kHz的魔角旋转，在1H通道上的射频场强高达140 kHz，在13C通道上大于50 kHz，以及每小时液氦消耗不到3升。我们已经获得了几种类型的蛋白质样品的核磁共振实验数据，包括冷冻溶液中的螺旋蛋白HP35，由β-淀粉样肽14-23残基形成的淀粉样纤维，以及磷脂双层中HIV-1 VPU跨膜蛋白的1-40残基。我们对这些样品进行了二维13C核磁共振测量，并对淀粉样蛋白样品进行了13C-13C偶极重耦合测量。其他申请目前正在进行中。