[Equilibrium surface charge distribution in phospholipid vesicles. III. Effect of nonelectrostatic factors]

The different curvature of the two vesicle layers causes a difference in the standard free energies mu01 and mu02 of the lipid molecules in the inside and outside layers. In the present paper the influence of this difference on the equilibrium surface charge distribution is studied. The values of mu02--mu01 in the numerical calculations were in the range 0--3 kT. The results show the relative influence of electrostatic and non electrostatic forces on the equilibrium distribution of the charged lipid molecules. In the range of low surface charge density the charged molecules localize predominantly in the outside layer at low electrolyte concentrations, and in the inside layer at high electrolyte concentrations. A good agreement between the theoretical data and the experimental results of Berden et al. [3] about the phosphatidylserine distribution in lecithin-phosphatidylserine vesicles is demonstrated.