Osmolyte effects: impact on the aqueous solution around charged and neutral spheres

Area of Science:

• Physical Chemistry
• Computational Biophysics
• Solution Chemistry

Background:

• Understanding solvation is crucial for chemical and biological processes.
• Osmolytes are known to modify water structure and solute interactions.
• The specific effects of urea and hydroxyectoine on charged solutes require detailed investigation.

Purpose of the Study:

• To investigate the influence of urea and hydroxyectoine on the solvation shell of charged and neutral model spheres.
• To elucidate how osmolyte characteristics and solute charge affect water properties and solvation thermodynamics.
• To analyze dynamic and thermodynamic contributions to solvation.

Main Methods:

• Atomistic molecular dynamics simulations.
• Thermodynamic integration for free energy calculations.
• Analysis of water properties: dipolar relaxation times, orientation, dielectric constants, diffusion coefficients, and preferential binding.

Main Results:

• Osmolytes significantly alter the solvation properties of charged and neutral spheres.
• Sphere charge and osmolyte type critically influence local water dynamics and thermodynamics.
• Enthalpic and entropic contributions to solvation vary based on solute charge and osmolyte presence.

Conclusions:

• Osmolytes like urea and hydroxyectoine play a significant role in modulating solute solvation in aqueous solutions.
• The interplay between solute charge and osmolyte properties dictates the structure and dynamics of the hydration shell.
• Detailed molecular simulations provide insights into the complex enthalpic and entropic factors governing solvation.