PROTONIC CONDUCTION OF ARTIFICIAL LIPID MEMBRANES

Electrical conductance of phospholipid bilayer membranes formed in various electrolyte solutions was studied with special reference to the kind of related charge carriers. The conductance was extremely low (10-5 -10-7 mho-cm-2), depending considerably on the lipid composition but little on both the concentration and kind of the electrolytes used, and it showed a complex dependence on the pH of the media on both sides of the membrane. Because of these experimental results, it seems preferable to assume that the charge carriers through the membrane are not the ions supplied from the electrolyte added to the solution, but protons and hydroxyl ions whose mobilities depend upon the sign and magnitude of the net charge on the membrane. Potential differences caused by diffusion of protons or hydroxyl ions across the membrane were also determined to prove the above assumption. © 1969, Applied Microbiology, Molecular and Cellular Biosciences Research Foundation. All rights reserved.