Time-Resolved Fluorescence Anisotropy Of Membrane Probes: Rotations Gated By Packing Fluctuations

Lesley Davenport.; Jay R Knutson; Ludwig Brand

doi:10.1117/12.945399

24 June 1988 Time-Resolved Fluorescence Anisotropy Of Membrane Probes: Rotations Gated By Packing Fluctuations

Lesley Davenport., Jay R Knutson, Ludwig Brand

Proceedings Volume 0909, Time-Resolved Laser Spectroscopy in Biochemistry; (1988) https://doi.org/10.1117/12.945399
Event: 1988 Los Angeles Symposium: O-E/LASE '88, 1988, Los Angeles, CA, United States

Abstract

Fluorescence emission anisotropy is a well established tool for measuring order in lipid bilayers. Coronene, a fluorescent membrane probe, with a mean fluorescence lifetime greater than 200ns, is sensitive to lipid chain disordering events that occur well after the decay of most other fluorescent probes. Further, its D6h planar symmetry provides exclusive detection of out-of-plane rotations. We have previously employed a compartmentalized gel-fluid equilibrium model to explain the time course of polarization for coronene in dimyristoylphosphatidylcholine (DMPC) and dipalmitoylphosphatidylcholine (DPPC) unilamellar vesicles (ULVs). We present here a more appropriate and complete model derived from Landau phase transition theory. A 'gating factor' is employed, which defines the number of lipid chains close to a coronene molecule which must disorder to allow the rotation of coronene. This model predicts a distribution of rotational correlation times (0i) that change with temperature. Our results indicate excellent agreement between theoretical anisotropy decays and data taken for coronene labelled DPPC large unilamellar vesicles (LUVs) measured at several temperatures up to the lipid melt transition temperature (Tc). The model can account for depolarization both at long times and in the first few nanoseconds of decay.

Citation Download Citation

Lesley Davenport., Jay R Knutson, and Ludwig Brand "Time-Resolved Fluorescence Anisotropy Of Membrane Probes: Rotations Gated By Packing Fluctuations", Proc. SPIE 0909, Time-Resolved Laser Spectroscopy in Biochemistry, (24 June 1988); https://doi.org/10.1117/12.945399

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