Estimation of the lateral distribution of molecules in two-component lipid bilayers.

A new formalism to investigate the lateral distribution of molecules in lipid bilayers has been developed, and the results have been applied to the case of phosphatidylcholine mixtures. It is demonstrated that the experimental phase diagrams for these mixtures can provide the necessary information to generate computer-simulated bilayers with the desired molecular interactions and lattice constraints. Analysis of these computer-generated bilayers allows calculation of the number of contacts between like and unlike molecules, the average size and number of compositional clusters, and the pair correlation functions. The results of this analysis provide a full quantitative description of the molecular organization of phosphatidylcholine within the plane of the bilayer.