Incidence of the temperature on the hydrophobic effect of alanine dissolved in water

MESON, ALEJANDRO M.; VERICAT, FERNANDO

Anales AFA

Asociación Física Argentina

Lugar: Tandil; Año: 2006 vol. 18 p. 269 - 271

0327-358X

The hydrophobic effect has played a central role in the study of proteins folding since W. Kauzmann proposed it as the main responsible for their collapse to the compact native conformation under normal physiological conditions. By changing the medium temperature a protein can be unfolded and folded again to its native conformation, without any other external action. This reveals the importance of studying the influence of the temperature on both aspects of the hydrophobic effect: the hydrophobic hydration and the hydrophobic interaction. In this work we consider a system formed by alanine residues dissolved in water and calculate the alanine-water and alanine-alanine radial distribution functions, at four different temperatures (4C, 25C, 50C and 75C). We use two complementary theoretic techniques: (1) a statistical mechanics theory of classical liquids, and (2) numerical simulations by molecular dynamics. From our results we conclude that when temperature is increased then the residue hydration diminishes and the alanine-alanine hydrophobic interaction becomes more intense.