Alcohols Reduce Lateral Membrane Pressures: Predictions from Molecular Theory

¹ Sandia National Laboratories

^* To whom correspondence should be addressed. E-mail: alfrisc{at}sandia.gov.

Submitted on June 21, 2006
Revised on July 20, 2006
Accepted on 28 August 2006

	Abstract

We explore the effects of alcohols on fluid lipid bilayers using a molecular theory with a coarse-grained model. We show that the trends predicted from the theory in the changes in area per lipid, alcohol concentration in the bilayer, and area compressibility modulus as a function of alcohol chain length and of the alcohol concentration in the solvent far from the bilayer follow those found experimentally. We then use the theory to study the effect of added alcohol on the lateral pressure profile across the membrane, and find that added alcohol reduces the surface tensions at both the headgroup/solvent and headgroup/tailgroup interfaces, as well as the lateral pressures in the headgroup and tailgroup regions. These changes in lateral pressures could affect the conformations of membrane proteins, providing a nonspecific mechanism for the biological effects of alcohols on cells.

Key Words: alcohol, classical density functional theory, lipid bilayers, model membranes

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