Lateral Distribution of Lipids in Membranes at High Pressure

摘要

This research is to study the lateral distribution of 1-palmitoyl-2(10-pyreny)decanoyl)-sn-glycerol-3-phosphatidylcholine (Pyr-PC) in dimyristoylphosphatidylcholine (DMPC) bilayer membranes. Fluorescence and statistical mechanics are employed. A series of dips were found in the plot of E/M (the ratio of excimer fluorescence to monomer fluorescence) vs. the mole fraction of Pyr-PC. The results can be interpreted in terms of the extended hexagonal super-lattice model. Based on this model, lipids in the Pyr-PC/DMPC binary mixtures are regularly distributed in the membrane. Pressure data further suggest that the bilayer membrane has more free volume at non-critical concentrations and more free volume when the regular distribution (as compared to the irregular region) reaches a local minimum. The computer simulation work further suggests that the area of regular arrangements have local maxima at the critical mole fractions if the repulsive interaction between Pyr-PCs is strong enough. Membrane biophysics.