[Anomalous surface conductivity of phospholipid membranes]

Surface conductivity (SC) of the double layer at the phospholipid liposome surface has been examined with quasi-elastic light scattering technique combined with pulse electrophoresis. 23Na NMR was used to study the interaction between sodium ions and liposomes. The migration of bound ions along the surface was shown to produce the main contribution to SC. The constants of binding the sodium ion to phospholipid heads were found to be 6 M-1 for phosphatidylserine and 80 M-1 for phosphatidyl acid. The exchange rate of ions bound to the lipid was estimated at 10(10) s-1.