Ring current shifts in 19F-NMR of membrane proteins
Ring current shifts in 19F-NMR of membrane proteins
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DOI：
10.1007/s10858-016-0022-4
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发表时间：
2016-05-01
影响因子：
2.7
通讯作者：
Wuthrich, Kurt
中科院分区：
文献类型：
--
作者：
Liu, Dongsheng;Wuthrich, Kurt
氟 19 NMR 标记物是有吸引力的报告基团，可用于复杂生物大分子系统的研究，特别是用于膜蛋白中功能相关构象平衡和速率过程的研究。 F-19-NMR 探针的优点包括 F-19 化学位移对非共价环境变化的高灵敏度。尽管如此，在 G 蛋白偶联受体 (GPCR) 的研究中，我们遇到了 F-19 化学位移对其他方法所涉及的构象变化没有反应的情况。这促使我们研究芳环电流场对 GPCR 中使用的 F-19-NMR 探针化学位移的可能影响。对先前报道的β(2)-肾上腺素能受体和哺乳动物视紫红质的(FF)-F-19-NMR数据的分析表明，所有表现出构象变化的F-19标记位点都位于芳香族残基附近。尽管与其他已知的对 F-19 化学位移的非共价效应相比，环电流效应很小，但有迹象表明，在研究 GPCR 的激活过程时，它们的贡献是显着的，因为观察到的激活相关的 F-19-NMR 化学位移在大小上与计算的环电流位移相当。因此，考虑环电流位移的影响可能有助于为未来 GPCR 激活的 F-19-NMR 研究确定有希望的本地或工程标记位点，并且可以获得有关 F-19 标记附近构象重排性质的新信息。那么，看看目前在 F-19-NMR 标记的膜蛋白研究中所指出的环电流位移的作用是否可以通过未来研究产生的更广泛的数据库得到证实，这也将是有趣的。
Fluorine-19 NMR markers are attractive reporter groups for use in studies of complex biomacromolecular systems, in particular also for studies of function-related conformational equilibria and rate processes in membrane proteins. Advantages of F-19-NMR probes include high sensitivity of the F-19 chemical shifts to variations in the non-covalent environment. Nonetheless, in studies of G protein-coupled receptors (GPCR) we encountered situations where F-19 chemical shifts were not responsive to conformational changes that had been implicated by other methods. This prompted us to examine possible effects of aromatic ring current fields on the chemical shifts of F-19-NMR probes used in GPCRs. Analysis of previously reported (FF)-F-19-NMR data on the beta(2)-adrenergic receptor and mammalian rhodopsin showed that all F-19-labeling sites which manifested conformational changes are located near aromatic residues. Although ring current effects are small when compared to other known non-covalent effects on F-19 chemical shifts, there is thus an indication that their contributions are significant when studying activation processes in GPCRs, since the observed activation-related F-19-NMR chemical shifts are comparable in size to the calculated ring current shifts. Considering the impact of ring current shifts may thus be helpful in identifying p romising indigenous or engineered labeling sites for future F-19-NMR studies of GPCR activation, and novel information may be obtained on the nature of conformational rearrangements near the F-19-labels. It will then also be interesting to see if the presently indicated role of ring current shifts in membrane protein studies with F-19-NMR markers can be substantiated by a more extensive data base resulting from future studies.