Membrane-structuring properties of bacterial long-chain alkylresorcinols.

To investigate the mechanism by which 5-n-alkyl(C19-C25)-resorcinols synthesized by certain bacteria of the Azotobacter genus affect the lipid bilayers of cellular membranes, planar bimolecular membranes were formed from these alkyl-resorcinols and from mixtures of those and typical bacterial phospholipids such as phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. The electrical properties and, in some instances, the stability of the prepared membranes have been studied. The alkylresorcinols have been found to associate with phospholipids to form oligomeric and polymeric complexes, thereby giving rise to modifications in the bilayer structure and properties. It has been shown that the same compounds suppress the mitochondrial respiration in the presence of NAD-dependent substrates, but they activate it if succinate is used as substrate. This fact is explained in terms of the interaction between the alkylresorcinols and membrane phospholipids.