PERTURBATION OF ARTIFICIAL AND BIOLOGICAL-MEMBRANES BY ORGANIC-COMPOUNDS OF ALIPHATIC, ALICYCLIC AND AROMATIC STRUCTURE

Aliphatic, alicyclic and aromatic hydrocarbons interact with biologica l membranes. Until now little has been known about their mode of inter action with the membrane bilayer and membrane integral proteins with t oxic effects to cells. The lipid theory hypothesis explains the toxic effects by the organic solvent-induced disorder in the lipid bilayer, which indirectly affects the function of membrane-embedded proteins. T he extent of bilayer perturbations is ascribed to the solvent accumula tion in the bilayer, which is related only to the lipophilicity of the molecule, independent of the chemical structure. Ln this study the fl uidizing effects of aliphatic, alicyclic and aromatic hydrocarbons wer e compared. Membrane fluidity changes were estimated from the pyrene e xcimer formation, using pyrene and pyrene derivatives to label specifi cally the localization of solvent molecules in the transverse plane of the bilayer. Liposomal, microsomal and synaptosomal membrane preparat ions were evaluated because proteins and cholesterol, as natural membr ane components, increase the bilayer order and reduce the organic solv ent membrane/buffer partition. In the concentration range investigated , only the aromatic solvents disorder the lipid bilayer, with the grea test perturbation in the centre of the bilayer. These results are rela ted to structural properties of the organic solvents investigated. Cop yright (C) 1996 Elsevier Science Ltd.