Equilibrium energy analysis of freeze-fracture planes in membranes

We have used equilibrium energy calculations to determine the most probable freeze-fracture planes in a lipid bilayer. Using a pairwise-summation computer method, we have generated numerical values for the Van der Waals potentials (electron shell repulsion, dispersion forces and electrostatic interactions) between molecules. We have compared our theoretical predictions with the experimental conclusion that the fracture planes occur normally between lipid molecules. These calculations also provide information about the composition of intramembranous particles, the potential for local clustering of single lipid types in the fluid membrane, and the importance of lipid molecules to the function of membrane proteins such as voltage-sensitive ion channels.