Ion-specific weak adsorption of salts and water/octanol transfer free energy of a model amphiphilic hexapeptide.
Summary of "Ion-specific weak adsorption of salts and water/octanol transfer free energy of a model amphiphilic hexapeptide."
An amphiphilic hexapeptide has been used as a model to quantify how specific ion effects induced by addition of four salts tune the hydrophilic/hydrophobic balance and induce temperature-dependant coacervate formation from aqueous solution. The hexapeptide chosen is present as a dimer with low transfer energy from water to octanol. Taking sodium chloride as the reference state in the Hofmeister scale, we identify water activity effects and therefore measure the free energy of transfer from water to octanol and separately the free energy associated to the adsorption of chaotropic ions or the desorption of kosmotropic ions for the same amphiphilic peptide. These effects have the same order of magnitude: therefore, both energies of solvation as well as transfer into octanol strongly depend on the nature of the electrolytes used to formulate any buffer. Model peptides could be used on separation processes based on criteria linked to "Hofmeister" but different from volume and valency.
Institut de Chimie Séparative de Marcoule (ICSM), UMR 5257 CEA/CNRS/UMII/ENSCM, CEA Centre de Marcoule, Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze cedex, France.
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Name: Physical chemistry chemical physics : PCCP
Medical and Biotech [MESH] Definitions
Metals with high specific gravity, typically larger than 5. They have complex spectra, form colored salts and double salts, have a low electrode potential, are mainly amphoteric, yield weak bases and weak acids, and are oxidizing or reducing agents (From Grant & Hackh's Chemical Dictionary, 5th ed)
Water containing no significant amounts of salts, such as water from RIVERS and lakes.
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