Selective averaging for high-resolution solid-state NMR spectroscopy of aligned samples
Selective averaging for high-resolution solid-state NMR spectroscopy of aligned samples
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DOI：
10.1016/j.jmr.2006.09.006
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发表时间：
2007-03-01
影响因子：
2.2
通讯作者：
Opella, Stanley J.
中科院分区：
文献类型：
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作者：
Nevzorov, Alexander A.;Opella, Stanley J.
固体核磁共振实验受益于在高场下进行，这是必不可少的，以便获得具有分辨率和灵敏度的光谱，用于在排列样品中测定蛋白质结构。由于可以应用的射频功率是有限的，特别是对于含水蛋白质样品，最重要的脉冲序列受到带宽限制，这是由于化学移位频率的相同传播导致的，这有助于分辨率。SAMP14是解决这些限制的脉冲序列。与目前使用的PISEMA和SAMMY实验相比，它产生的分离的局部场光谱在整个光谱上具有更窄和更均匀的线宽。此外，它更容易在商用光谱仪上设置，并且可以作为构建块合并到其他多维脉冲序列中。这是用二维hetor实验来说明的，在这个实验中，在很宽的化学位移频率范围内，将酰胺质子的极化转移到它们直接键合的氮是至关重要的。提出了高功率射频脉冲下自旋哈密顿量的量子力学处理方法，给出了SAMP14的比例因子以及射频脉冲的持续时间以实现最佳解耦。(c) 2006爱思唯尔公司版权所有。
Solid-state NMR experiments benefit from being performed at high fields, and this is essential in order to obtain spectra with the resolution and sensitivity required for applications to protein structure determination in aligned samples. Since the amount of rf power that can be applied is limited, especially for aqueous protein samples, the most important pulse sequences suffer from bandwidth limitations resulting from the same spread in chemical shift frequencies that aids resolution. SAMP14 is a pulse sequence that addresses these limitations. It yields separated local field spectra with narrower and more uniform linewidths over the entire spectrum than the currently used PISEMA and SAMMY experiments. In addition, it is much easier to set up on commercial spectrometers and can be incorporated as a building block into other multidimensional pulse sequences. This is illustrated with a two-dimensional HETCOR experiment, where it is crucial to transfer polarization from the amide protons to their directly bonded nitrogens over a wide range of chemical shift frequencies. A quantum-mechanical treatment of the spin Hamiltonians under high-power rf pulses is presented which gives the scaling factor for SAMP14 as well as the durations of the rf pulses to achieve optimal decoupling. (c) 2006 Elsevier Inc. All rights reserved.