Fluorine-19 NMR and computational quantification of isoflurane binding to the voltage-gated sodium channel NaChBac.

摘要: Voltage-gated sodium channels (NaV) play an important role in general anesthesia. Electrophysiology measurements suggest that volatile anesthetics such as isoflurane inhibit NaV by stabilizing the inactivated state or altering inactivation kinetics. Recent computational studies suggested existence of multiple binding sites NaV, but experimental data are lacking. Here we use site-directed placement 19F probes NMR experiments to quantify bacterial voltage-gated channel NaChBac. were introduced individually S129 and L150 near S4-S5 linker, L179 S208 at extracellular surface, T189 ion selectivity filter, all phenylalanine residues. Quantitative analyses saturation transfer difference (STD) spectroscopy showed a strong interaction with S129, T189, S208; relatively weakly L150; almost undetectable An orientation preference was observed for bound S208, not L150. We conclude inhibits NaChBac two distinct mechanisms: (i) blocker base (ii) modulator restrict pivot motion linker critical hinge controls gating S6.