Ion solvation by channel carbonyls characterized by 17O solid-state NMR at 21 T
Ion solvation by channel carbonyls characterized by 17O solid-state NMR at 21 T
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DOI：
10.1021/ja0535413
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发表时间：
2005-08-31
影响因子：
15
通讯作者：
Cross, TA
中科院分区：
文献类型：
--
作者：
Hu, J;Chekmenev, EY;Cross, TA
最近可用的四极磁场提供了新的机会，在生物固体中的四极核的研究，因为显着提高灵敏度和分辨率与减少二阶四极相互作用。在这里，我们提出了一种新的方法来理解离子溶剂化的功能和能量的通道使用固态17O NMR光谱的单site17O标记短杆菌肽A。在冻干材料的粉末样品中获得的化学位移和四极耦合参数与文献中所示的羰基氧相似。在脂质双层中，发现Leu10的羰基17O各向异性化学位移，其中三个羰基氧有助于短杆菌肽A中的离子结合位点，改变40 ppm时，K+离子结合到通道，表现出高灵敏度，这样的相互作用。此外，考虑到羰基17 O化学位移的大幅度（>500 ppm），相对于磁场B 0对齐的双层中各向异性17 O化学位移的记录提供了类似于15 N和13 C各向异性化学位移的高质量结构限制。
Recently available ultrahigh magnetic fields offer new opportunities for studies of quadrupole nuclei in biological solids because of the dramatic enhancement in sensitivity and resolution associated with the reduction of second-order quadrupole interactions. Here, we present a new approach for understanding the function and energetics of ion solvation in channels using solid-state17O NMR spectroscopy of single-site17O-labeled gramicidin A. The chemical shift and quadrupole coupling parameters obtained in powder samples of lyophilized material are similar to those shown in the literature for carbonyl oxygens. In lipid bilayers, it is found that the carbonyl17O anisotropic chemical shift of Leu10, one of the three carbonyl oxygens contributing to the ion binding site in gramicidin A, is altered by 40 ppm when K+ion binds to the channel, demonstrating a high sensitivity to such interactions. Moreover, considering the large breadth of the carbonyl17O chemical shift (>500 ppm), the recording of anisotropic17O chemical shifts in bilayers aligned with respect to magnetic fieldB0offers high-quality structural restraints similar to15N and13C anisotropic chemical shifts.