Liposomal Membranes. 2. Synthesis of a Novel Pyrene-Labeled Lecithin and Structural Studies on Liposomal Bilayers

Article abstract of DOI:10.1021/ja00523a035

A novel pyrene-labeled phosphatidylcholine, 1,2-bis<ω-(1-pyreno)decanoyl>-sn-glycero-3-phosphorylcholine (DPDL), was synthesized for use in structural studies on the liposomal bilayers.From the fluorescence measurements on DPDL incorporated into the phospholipid bilayers as well as in organic solvents and aqueous buffered solutions, the following interesting information was obtained. (1) The probe DPDL is intercalated in a well-ordered fashion in the very hydrophobic domain of egg and dipalmitoylphosphatidylcholine bilayers. (2) Without cholesterol and /or below the phase-transition temperature, DPDL is arranged with the lipid-separated conformation in the shrunk liposomal bilayers (Figure 9d). (3) Increasing the mobility of lipid molecules by the addition of cholesterol and/or by elevating temperatures causes a conformational change of DPDL in the bilayers from the lipid-separated conformation to the intimate one (Figure 9c).