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Intramolecular Excimer Formation of Pyrene-Labeled Lipids in Lamellar and Inverted Hexagonal Phases of Lipid Mixtures Containing Unsaturated Phosphatid
Biophysical Chemistry (1991)
  • Kwan H Cheng, Texas Tech University
  • Sun-Yung Chen
  • Peter Butko
  • B Wieb Van der Meer
  • Pentti Somerharju
Abstract

The rates of intramolecular excimer formation of di(1′-pyrenemyristoyl)phosphatidylcholine (dipyPC) in dioleoylphosphatidylethanolamine (DOPE), egg PE/diolein (DG) and dilinoleoyl-PE (DLPE)/1-palmitoyl-2-oleoyl-PC (POPC) were studied at different temperatures and lipid compositions. Both the excimer-to-monomer intensity ratio and the excimer association rate constant were employed to quantify the rate of excimer formation. The latter was calculated from the measured monomer fluorescence lifetime of dipyPC. We observed that the rate of excimer formation was sensitive to either the temperature-induced or lipid composition-induced lamellar-to-inverted hexagonal phase transition of the above lipid systems. As the lipids entered the inverted hexagonal phase, the rate of excimer formation increased at the temperature-induced phase transition for DOPE, but decreased at the composition-induced phase transition for both TPE/DG and DLPE/POPC systems by increasing the DG% and decreasing the PC%, respectively. We conclude that the rate of intramolecular excimer formation of dipyPC in the non-lamellar phase is influenced both by the intra-lipid free volume of the hydrocarbon region and the intra-rotational dynamics of the two lipid acyl chains.

Keywords
  • Intramolecular excimer formation,
  • Lipid non-bilayer phase,
  • Phase transition,
  • Fluorescence spectroscopy,
  • Phosphatidylethanolamine,
  • Diacylglycerol
Publication Date
February, 1991
Citation Information
Kwan, H. C., Chen, S.-Y., Butko, P., Van Der Meer, B. W., & Somerharju, P. (1991). Intramolecular excimer formation of pyrene-labeled lipids in lamellar and inverted hexagonal phases of lipid mixtures containing unsaturated phosphatid. Biophysical Chemistry, 39, 137-144. doi: 10.1016/0301-4622(91)85015-I