1 research outputs found
On the Hofmeister Effect: Fluctuations at the ProteināWater Interface and the Surface Tension
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 proteināwater interfacial tension were determined.
At 300 K, the chaotropic ClO<sub>4</sub><sup>ā</sup> and NO<sub>3</sub><sup>ā</sup> 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<sup>ā</sup> 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 proteināwater
interface in Hofmeister phenomena, and provide a computational method
for the determination of the proteināwater interfacial tension,
establishing a link between the phenomenological and microscopic description
of proteināwater interfaces