Trimethylamine<i>N</i>-oxide (TMAO) resists the compression of water structure by magnesium perchlorate: terrestrial kosmotrope<i>vs.</i>Martian chaotrope

Laurent, Harrison; Soper, A. K.; Dougan, Lorna

doi:10.1039/c9cp06324b

Cited by 11 publications

(30 citation statements)

References 87 publications

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“…Other mechanisms may contribute to the increase in enzyme activity. Owing to the chaotropic nature of the perchlorate anion at the high concentrations we tested, the hydrogen-bond network structure of the solvent H 2 O is perturbed 9 – 12 , which might change the hydration properties of the reactants (and hence their activities), and, for example, help facilitate dehydration of the substrate and active site in the course of the reaction. Additionally, the extent to which α-chymotrypsin is preferentially hydrated may differ across temperatures when in the presence of solutes such as perchlorate salts and glycine.…”

Section: Discussionmentioning

confidence: 99%

“…Further, highly chaotropic anions, such as perchlorates (ClO 4 - ), which are found pervasively on Mars 2 , have been shown to act as a protein denaturant 3 owing to their ability to interact with the surface of biomacromolecules 4 – 8 . They are also able to perturb the water structure and therefore are likely to perturb hydrogen bonding, including within that of water itself 9 – 12 .…”

Section: Introductionmentioning

confidence: 99%

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Perchlorate salts confer psychrophilic characteristics in α-chymotrypsin

Gault

Jaworek

Winter

et al. 2021

Sci Rep

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Studies of salt effects on enzyme activity have typically been conducted at standard temperatures and pressures, thus missing effects which only become apparent under non-standard conditions. Here we show that perchlorate salts, which are found pervasively on Mars, increase the activity of α-chymotrypsin at low temperatures. The low temperature activation is facilitated by a reduced enthalpy of activation owing to the destabilising effects of perchlorate salts. By destabilising α-chymotrypsin, the perchlorate salts also cause an increasingly negative entropy of activation, which drives the reduction of enzyme activity at higher temperatures. We have also shown that α-chymotrypsin activity appears to exhibit an altered pressure response at low temperatures while also maintaining stability at high pressures and sub-zero temperatures. As the effects of perchlorate salts on the thermodynamics of α-chymotrypsin’s activity closely resemble those of psychrophilic adaptations, it suggests that the presence of chaotropic molecules may be beneficial to life operating in low temperature environments.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Perchlorate salts confer psychrophilic characteristics in α-chymotrypsin

Gault

Jaworek

Winter

et al. 2021

Sci Rep

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“…Each atom present in the sample is characterized by a reference potential consisting of a charge q and the Lennard-Jones parameters σ and ε using the standard Lorentz–Berthelot mixing rules (see Table S1 for numerical values for each atomic species present in the simulations adopted from Soper and Weckström). Water molecules are modeled using the SPC/E potential, which has been shown to accurately model dynamics and structure and has been previously used in a host of EPSR studies on aqueous solutions. ,,,,− To remain consistent with the previous neutron scattering and EPSR study of aqueous potassium halides of Soper and Weckström, the ions were modeled using the same reference potentials as the original study. The simulations contain 5000 water molecules, and the concentration of ions is varied by introducing 60, 120, or 240 ion pairs for each of the three studied concentrations.…”

Section: Methodsmentioning

confidence: 99%

“…Calculation of Dipole Angle Distribution, Enthalpy of Hydration, and Distance Dependence on Enthalpic Interactions between Central Ions and Surrounding Water Molecules. Building on previous studies, 51,52 we have extracted further information from the atomic coordinates produced through EPSR to distinguish between bulk water molecules and hydration water molecules and perform a detailed analysis of various microenvironments present in the aqueous potassium halide solutions. The process of EPSR produces a simulated box of atoms consistent with the experimental neutron scattering data, each of which is given a coordinate relative to the center of the box in the x, y, and z directions.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Bridging Structure, Dynamics, and Thermodynamics: An Example Study on Aqueous Potassium Halides

et al. 2021

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Aqueous salt systems are ubiquitous in all areas of life. The ions in these solutions impose important structural and dynamic perturbations to water. In this study, we employ a combined neutron scattering, nuclear magnetic resonance, and computational modeling approach to deconstruct ion-specific perturbations to water structure and dynamics and shed light on the molecular origins of bulk thermodynamic properties of the solutions. Our approach uses the atomistic scale resolution offered to us by neutron scattering and computational modeling to investigate how the properties of particular short-ranged microenvironments within aqueous systems can be related to bulk properties of the system. We find that by considering only the water molecules in the first hydration shell of the ions that the enthalpy of hydration can be determined. We also quantify the range over which ions perturb water structure by calculating the average enthalpic interaction between a central halide anion and the surrounding water molecules as a function of distance and find that the favorable anion−water enthalpic interactions only extend to ∼4 Å. We further validate this by showing that ions induce structure in their solvating water molecules by examining the distribution of dipole angles in the first hydration shell of the ions but that this perturbation does not extend into the bulk water. We then use these structural findings to justify mathematical models that allow us to examine perturbations to rotational and diffusive dynamics in the first hydration shell around the potassium halide ions from NMR measurements. This shows that as one moves down the halide series from fluorine to iodine, and ionic charge density is therefore reduced, that the enthalpy of hydration becomes less negative. The first hydration shell also becomes less well structured, and rotational and diffusive motions of the hydrating water molecules are increased. This reduction in structure and increase in dynamics are likely the origin of the previously observed increased entropy of hydration as one moves down the halide series. These results also suggest that simple monovalent potassium halide ions induce mostly local perturbations to water structure and dynamics.

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“…Figure S4(b).Bulk waterwater hydrogen bond interaction energy distribution. Definition of a water-water hydrogen bond taken from Laurent et al2,3 . Only data from 0.6 and 1.2 mol/kg H2O concentration solutions shown for clarity.…”

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confidence: 99%

Bridging Structure, Dynamics, and Thermodynamics: An Example Study on Aqueous Potassium Halides

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TrimethylamineN-oxide (TMAO) resists the compression of water structure by magnesium perchlorate: terrestrial kosmotropevs.Martian chaotrope

Abstract: Neutron diffraction and computational modelling provide insight into water structure.

Cited by 11 publications

References 87 publications

Perchlorate salts confer psychrophilic characteristics in α-chymotrypsin

Perchlorate salts confer psychrophilic characteristics in α-chymotrypsin

Bridging Structure, Dynamics, and Thermodynamics: An Example Study on Aqueous Potassium Halides

Bridging Structure, Dynamics, and Thermodynamics: An Example Study on Aqueous Potassium Halides

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