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Updated: Jul 7, 2026
09:48
In Situ Characterization of Hydrated Proteins in Water by SALVI and ToF-SIMS
Published on: February 15, 2016
Effect of high salt concentrations on water structure
1European Molecular Biology Laboratory, Grenoble Outstation, BP 156, 38042 Grenoble Cedex, France.
Nature
|November 23, 1995
Summary
Ions in water solutions disrupt its structure, mimicking high pressures. This ion-specific effect, linked to partial molar volume, influences protein precipitation and salting-out phenomena.
Area of Science:
- Physical chemistry
- Solution chemistry
- Biophysical chemistry
Background:
- Water's tetrahedral structure is sensitive to pressure and temperature.
- Ions in solution may perturb water's hydrogen-bonded network.
- Understanding ion-water interactions is crucial for various chemical and biological processes.
Purpose of the Study:
- To compare the structural effects of applied pressure versus high salt concentrations on water.
- To investigate the ion-specific nature of these structural perturbations.
- To correlate ion-induced structural changes with protein salting-out efficacy.
Main Methods:
- Neutron diffraction was employed to probe the structure of water under different conditions.
- High salt concentrations and applied pressures were systematically varied.
- Structural changes were analyzed in relation to ion properties.
Main Results:
- Ions induce structural changes in water equivalent to high pressures (over 1000 atm at a few mol/L).
- The magnitude of this pressure effect is specific to the ion species.
- A correlation was observed between the induced pressure and the ion's efficacy in protein salting-out.
Conclusions:
- Ionic perturbation of water structure is analogous to applying significant hydrostatic pressure.
- Partial molar volume of ions relative to water molecules explains the observed structural changes.
- The study provides a molecular basis for understanding ion-specific effects in protein precipitation and solution behavior.
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