Research Summary
Specific ion effects on protein interfaces have been observed for many years, but comprehensive explanations regarding the mechanism by which ions interact with proteins and more general aqueous interfaces are still under investigation. Ion specificity on protein stability is influenced by numerous contributions and interactions between the solution and the protein. However, the most significant contribution is arguably the hydrophobic effect, specifically the change in free energy when water molecules are liberated from the interfacial region upon protein folding.
In the work presented here, the effects of different ions on the critical micelle concentration (CMC) of 1,2-Hexanediol were examined to study salt effects on hydrophobicity using fluorescence spectroscopy. Our results demonstrate that both anions and cations exhibit specific effects on hydrophobic interactions. However, the origin of these specific ion effects differs for cations and anions. Cation-specific effects are caused by their ability to form cavities in solution, while anion-specific effects arise from their ability to interact with the interface.
These findings are of interest to researchers in the protein folding field, providing significant experimental hydrophobicity data that can assist theoretical biologists in their attempts to predict protein structures.
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