Order and fluidity of lipid membranes as determined by fluorescence anisotropy decay |
| |
Authors: | L Best E John F Jähnig |
| |
Institution: | (1) Max-Planck-Institut für Biologie, Corrensstrasse 38, D-7400 Tübingen, Federal Republic of Germany;(2) Present address: Die Holzwerkstatt, Gartenstrasse 29, D-6112 Groß-Zimmern, Federal Republic of Germany |
| |
Abstract: | The fluorescence anisotropy decay of four different probes in bilayers of dimyristoylphosphatidylcholine was measured. The probes are diphenylhexatriene, diphenyloctatetraene, trimethylaminodiphenylhexatriene, and trans-parinaric acid. The data for each probe were analyzed in terms of two orientational order parameters, the ordinary order parameter and a higher one, and two rotational diffusion coefficients. The order parameters are largely independent of probe size, but depend on the position of the probes along the membrane normal, thus reflecting the profile of lipid order. If a probe is located in the plateau region of lipid order, its order parameters are interpreted as representing the rigid-body order of lipids. According to this interpretation, the total lipid order in the plateau region originates about equally from rigid-body order and conformational order. The two order parameters obtained for each probe are used to derive approximate angular distributions of the probe molecules. The diffusion coefficient for rotation about the long molecular axis is found to be infinitely large, indicating unhindered rotation about this axis. The diffusion coefficient for rotation about the short molecular axes is evaluated for a viscosity which results as 0.2 poise. This viscosity for rotational diffusion is an order of magnitude smaller than the viscosity for lateral diffusion indicating that at least two viscosities are required to characterize the fluidity of a lipid membrane.Abbreviations FAD
fluorescence anisotropy decay
- DMR
deuterium magnetic resonance
- ESR
electron spin resonance
- DMPC
dimyristoylphosphatidylcholine
- DPPC
dipalmitoylphosphatidylcholine
- DPH
1,6-diphenyl-1,3,5-hexatriene
- DPO
1,6-diphenyl-1,3,5,7-octatetraene
- TMA-DPH
1-4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene
- tPnA
trans-parinaric acid
- NPN
N-phenyl-1-naphthylamine
- BBO
2,5-bis(4-biphenylyl)oxazole |
| |
Keywords: | Lipid bilayers fluorescence probes order parameters diffusion coefficients viscosity |
本文献已被 SpringerLink 等数据库收录! |
|