MICROHYDRATION OF Mg²⁺(CH₃COO⁻) ION PAIRS FOLLOWED BY IR LASER SPECTROSCOPY: INSIGHTS INTO THE WATER-MEDIATED IONIC INTERACTIONS IN THE MAGNESIUM TRANSPORT CHANNEL

Bardaud, Jean-Xavier

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https://hdl.handle.net/2142/122434 Copy

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Title

MICROHYDRATION OF Mg²⁺(CH₃COO⁻) ION PAIRS FOLLOWED BY IR LASER SPECTROSCOPY: INSIGHTS INTO THE WATER-MEDIATED IONIC INTERACTIONS IN THE MAGNESIUM TRANSPORT CHANNEL

Author(s)

Bardaud, Jean-Xavier

Contributor(s)

• Fujii, Masaaki
• Ishiuchi, Shun-ichi
• Hirata, Keisuke
• Takayanagi, Hikaru
• Mons, Michel
• Brenner, Valerie
• Gloaguen, Eric

Issue Date

2023-06-21

Keyword(s)

Mini-symposium: Spectroscopy with Cryogenic Ion Traps

Abstract

Ionic interactions play a crucial role in ion transport and selectivity to maintain cellular ion homeostasis. For example, the Mg²⁺ channel is a membrane protein that regulates Mg²⁺ cation concentration on both sides of the cell membrane. Crystal structure of the Magnesium Transport E channel suggests a transport mechanism for Mg²⁺ ions involving the motion of hexa-hydrated Mg²⁺ cations recognized through water-mediated ionic interactions between the Mg²⁺ cation and the carboxylate groups of the channel interior.ᵃ In order to characterize these water-mediated ionic interactions, we investigated Mg²⁺(CH₃COO⁻)(H₂O)n clusters. We probed their structures from n = 4 to 17 by measuring cryogenic gas phase infrared spectra, further interpreted by high-level quantum chemistry DFT-D calculations of vibrational frequencies. This comparison allowed us to investigate size-selected microhydrated Mg²⁺ ion pairs. In accordance with previous findings obtained on hydrated calciumᵇ and bariumᶜ acetate clusters, hydration by 6 water molecules is insufficient to induce the ion separation. Nonetheless, partially-separated or separated ion pairs are formed from at least 10 water molecules, and more significantly with 14 water molecules. These results highlight the necessity of a second water-mediated ionic interaction for the transport of Mg²⁺ within the channel and possibly in cooperation with other interactions, such as involving carbonyl groups, as suggested by the crystal structure.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122434

DOI

https://doi.org/10.15278/isms.2023.6732

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