Properties of lipid bilayer membranes made from lipids containing phytanic acid.

Besides the preparation of phytanic acid (3,7,11,15-tetramethylhexadecylic acid) according to the Dumas-Stass reaction, the synthesis of four different lipids containing phytanic acid residues is described. Diphytanoyl phosphatidylcholine was synthesized beginning from glycerylphosphorylcholine, whereas the other lipids, diphytanoyl phosphatidylethanolamine, diphytanoyl phosphatidylserine and monophytanoyl glyceride were prepared by total synthesis. Some properties of lipid bilayer membranes made from the lipids containing phytanic acid were investigated. The specific capacity of these membranes was measured. Its value of approximately 400 nF cm-2 was found to be similar to the value of membranes from lipids with unbranched fatty acid residues. Charge pulse experiments were performed using dipicrylamine as a molecular probe of membrane structure. The results were discussed on the basis of a higher viscosity of the membranes from lipids containing phytanic acid residues compared with unbranched fatty acid residues.