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Trimethylamine N-oxide Resists The Compression of Water Structure by Magnesium Perchlorate : Terrestrial Kosmotrope vs Martian Chaotrope

Abstract

The presence of magnesium perchlorate (Mg(ClO4)2) as the dominating ionic compound in the Martian regolith and the recent discovery of a subsurface lake on Mars suggests that beneath the Martian surface may lie an aqueous environment suitable for life, rich in chaotropic ions. Closer to Earth, terrestrial organisms use osmolytes, such as trimethylamine N-oxide (TMAO), to overcome the biologically damaging effects of pressure. While previous studies have revealed that Mg(ClO4)2 acts to modify water structure as if it has been pressurized, little is known about the competing effects of chaotropes and kosmotropes. Therefore the question here is whether TMAO can help to preserve the hydrogen bond network of water against the pressurising effect of Mg(ClO4)2? We address this question using neutron scattering, computational modelling using Empirical Potential Structure Refinement (EPSR) analysis, and a new approach to quantifying hydrogen bond conformations and energies. We find that the addition of 1.0 M TMAO to 0.2 M Mg(ClO4)2 or 2.7 M Mg(ClO4)2 is capable of partially restoring the hydrogen bond network of water, and the fraction of water molecules in conformations associated with hydrogen bond switching. This suggests that terrestrial protecting osmolytes could provide a protective mechanism to the extremes found in Martian environments for biological systems.

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Supplementary files

Article information


Submitted
22 Nov 2019
Accepted
05 Feb 2020
First published
14 Feb 2020

Phys. Chem. Chem. Phys., 2020, Accepted Manuscript
Article type
Paper

Trimethylamine N-oxide Resists The Compression of Water Structure by Magnesium Perchlorate : Terrestrial Kosmotrope vs Martian Chaotrope

H. Laurent, A. K. Soper and L. Dougan, Phys. Chem. Chem. Phys., 2020, Accepted Manuscript , DOI: 10.1039/C9CP06324B

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