Highlighting Cavities in Proteins by NMR Using Sulfur Hexafluoride as a Spy Molecule

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• 作者：Luca Fusaro ; Emanuela Locci ; Adolfo Lai ; Michel Luhmer
• 刊名：Journal of Physical Chemistry B
• 出版年：2010
• 出版时间：March 11, 2010
• 年：2010
• 卷：114
• 期：9
• 页码：3398-3403
• 全文大小：212K
• 年卷期：v.114,no.9(March 11, 2010)
• ISSN：1520-5207

文摘

Cavities in proteins can be studied experimentally by using some detectable atoms, such as xenon, or molecules which act as reporter, such as a spy. The interest of sulfur hexafluoride (SF₆) for probing hydrophobic cavities by solution-state NMR is investigated. The wheat nonspecific lipid transfer protein (LTP) was selected as a model system for this purpose. The binding of SF₆ is straightforwardly detected by the ¹⁹F chemical shift, line width, or longitudinal relaxation time measurements, which can be carried out at low SF₆ concentration without interference from resonances of the protein. Most interestingly, the binding of SF₆ gives rise to selective intermolecular ¹H{¹⁹F} heteronuclear Overhauser effects (HOEs). Molecular dynamics simulation and NMR spectrum modeling show that the experimental HOESY spectra are consistent with ¹H{¹⁹F} HOEs arising from SF₆ in the cavity of LTP. SF₆ is found to be an advantageous alternative to hyperpolarized ¹²⁹Xe and small organic compounds for probing cavities in proteins by solution-state NMR.