LIPID MONOLAYER IMAGE DIPOLES

A simple model is described for calculating the electrostatic energy o f lipid domains at the air-water interface, taking account of dipole-d ipole repulsions between the lipid molecules themselves, as well as in teractions between the molecular dipoles and image dipoles in the subp hase, The model assumes that the molecular dipoles within the monolaye r arise from the terminal methyl groups of the hydrophobic hydrocarbon chains of the lipid molecules, and that on average they are oriented perpendicular to the plane of the monolayer, With this model the role of the subphase is to enhance rather than suppress the effects of dipo le-dipole repulsions.