title: Highlighting cavities in proteins by NMR using sulfur hexafluoride as a spy molecule.
abstract: 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 (SF(6)) 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 SF(6) is straightforwardly detected by the (19)F chemical shift, line width, or longitudinal relaxation time measurements, which can be carried out at low SF(6) concentration without interference from resonances of the protein. Most interestingly, the binding of SF(6) gives rise to selective intermolecular (1)H{(19)F} heteronuclear Overhauser effects (HOEs). Molecular dynamics simulation and NMR spectrum modeling show that the experimental HOESY spectra are consistent with (1)H{(19)F} HOEs arising from SF(6) in the cavity of LTP. SF(6) is found to be an advantageous alternative to hyperpolarized (129)Xe and small organic compounds for probing cavities in proteins by solution-state NMR.
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Cagliari, Cittadella Universitaria di Monserrato, 09042 Monserrato (CA), Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Fusaro
authors.forename: Emanuela
authors.initials: E
authors.lastname: Locci
authors.forename: Adolfo
authors.initials: A
authors.lastname: Lai
authors.forename: Michel
authors.initials: M
authors.lastname: Luhmer
mesh_terms: D057927:Hydrophobic and Hydrophilic Interactions; D009682:Magnetic Resonance Spectroscopy; D056004:Molecular Dynamics Simulation; D011506:Proteins / Q000737:chemistry*; D013459:Sulfur Hexafluoride / Q000737:chemistry*
chemical_list: D011506:Proteins; D013459:Sulfur Hexafluoride