Biophysical Journal 71: 600-608 (1996)
© 1996 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wallqvist, A Articles by Covell, D G Search for Related Content PubMed PubMed Citation Articles by Wallqvist, A Articles by Covell, D G

On the origins of the hydrophobic effect: observations from simulations of n-dodecane in model solvents.

Frederick Cancer Research and Development Center, National Cancer Institute, Science Applications International Corporation, Frederick, Maryland 21702, USA. wallqvis@ncifcrf.gov

ABSTRACT

The importance of the small size of a water molecule as contributing to the hydrophobic effect is examined from simulations of n-dodecane in different solvents. The earlier observations of the origin of hydrophobicity, derived from cavity formations by Pratt and Pohorille (1992, Proc. Natl. Acad. Sci. USA. 89:2995-2999) and Madan and Lee (1994, Biophys. Chem, 51:279-289), are shown to be largely consistent for a hydrocarbon-induced water pocket. In effect, the small size of a water molecule limits the probability (and hence free energy) of finding an appropriate void in the fluid that will accommodate a solute. In this work a simulated collapse of an n-dodecane molecule in H2O, CCl4, and a water-like Lennard-Jones solvent indicates that the induced entropy and enthalpy changes are qualitatively similar for hydrogen-bonded and Lennard-Jones water solvents. These results suggest that a large part of the hydrophobic response of solutes in aqueous solutions is due to the small size of the solvent. Important quantitative differences between the studied water solvents indicate that the hydrogen-bonded properties for water are still needed to determine the overall hydrophobic response.