title: On the Hofmeister effect: fluctuations at the protein-water interface and the surface tension.
abstract: We performed molecular dynamics simulations on the tryptophane-cage miniprotein using a nonpolarizable force field, in order to model the effect of concentrated water solutions of neutral salts on protein conformation, which is a manifestation of Hofmeister effects. From the equilibrium values and the fluctuations of the solvent accessible surface area of the miniprotein, the salt-induced changes of the mean value of protein-water interfacial tension were determined. At 300 K, the chaotropic ClO4(-) and NO3(-) decreased the interfacial tension according to their position in the Hofmeister series (by approximately 5 and 2.7 mN/m, respectively), while the kosmotropic F(-) increased it (by 1 mN/m). These values were compared to those obtained from the Gibbs equation using the excess surface adsorption calculated from the probability distribution of the water molecules and ions around the miniprotein, and the two sets were found to be very close to each other. Our results present a direct evidence for the central role of interfacial tension and fluctuations at the protein-water interface in Hofmeister phenomena, and provide a computational method for the determination of the protein-water interfacial tension, establishing a link between the phenomenological and microscopic description of protein-water interfaces.
authors: MTA-SZTE Supramolecular and Nanostructured Materials Research Group of Hungarian Academy of Sciences, University of Szeged , H-6720 Szeged, Hungary.
authors: Ferenc
authors: F
authors: Bogár
authors: Ferenc
authors: F
authors: Bartha
authors: Zoltán
authors: Z
authors: Násztor
authors: László
authors: L
authors: Fábián
authors: Balázs
authors: B
authors: Leitgeb
authors: András
authors: A
authors: Dér
mesh_terms: D000595:Amino Acid Sequence; D056004:Molecular Dynamics Simulation; D010455:Peptides / Q000737:chemistry; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*; D013500:Surface Tension; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D010455:Peptides; D011506:Proteins; D014867:Water