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Fluorine-19 NMR and computational quantification of isoflurane binding to the voltage-gated sodium channel NaChBac
Journal article   Open access

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

Monica N Kinde, Vasyl Bondarenko, Daniele Granata, Weiming Bu, Kimberly C Grasty, Patrick J Loll, Vincenzo Carnevale, Michael L Klein, Roderic G Eckenhoff, Pei Tang, …
Proceedings of the National Academy of Sciences - PNAS, v 113(48), pp 13762-13767
29 Nov 2016
PMID: 27856739
url
https://doi.org/10.1073/pnas.1609939113View
Published, Version of Record (VoR)Maybe Open Access (Publisher Bronze) Open

Abstract

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

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Collaboration types
Domestic collaboration
Web of Science research areas
Multidisciplinary Sciences
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