Low concentrated hydroxyectoine solutions in presence of DPPC lipid bilayers: A computer simulation study

•Numerical study of the kosmotropic properties of hydroxyectoine in presence of DPPC lipid bilayers•Strengthening of the water hydrogen bond network in presence of hydroxyectoine•Validation of preferential exclusion mechanism for hydroxyectoine in terms of Kirkwood-Buff theory•Increased surface pressure for DPPC lipid bilayers with increased hydroxyectoine concentration•Visibility of co-solute effects on DPPC lipid bilayers for low and physiological concentrations

The influence of hydroxyectoine on the properties of the aqueous solution in presence of DPPC lipid bilayers is studied via semi-isotropic constant pressure (NPT) Molecular Dynamics simulations. We investigate the solvent-co-solute behavior in terms of Kirkwood-Buff integrals as well as hydrogen bond life times for an increasing hydroxyectoine concentration up to 0.15 mol/L. The observed preferential exclusion mechanism identifies hydroxyectoine as a kosmotropic osmolyte. Our findings with regard to the DPPC lipid bilayer indicate an increase of the surface pressure as well as the solvent accessible surface area in presence of higher hydroxyectoine concentrations. The results are in agreement to the outcome of recent experiments. With this study, we are able to validate the visibility of co-solute-solute-solvent effects for low and physiologically relevant osmolyte concentrations.

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