BINDING AND RELAXATION BEHAVIOR OF PRODAN AND PATMAN IN PHOSPHOLIPID-VESICLES - A FLUORESCENCE AND H-1-NMR STUDY

The relative location, binding behaviour and the solvent relaxation be haviour of the polarity sensitive membrane probes 6-propionyl-2-(dimet hylamino)naphthalene and 2-[[trimethylammoniumethyl]methylamino]naphth alene chloride in vesicles composed of 1,2-dimyristoyl-sn-glycero-3-ph osphatidylcholine or egg yolk lecithin have been compared using steady -state and time-resolved fluorescence as well as high resolution NMR m easurements. The reconstructed time-resolved emission spectra show una mbiguously that the observed spectral shifts in vesicle systems have t o be assigned to time-dependent solvent relaxation processes rather th an to a probe relocation mechanism. All fluorescence as well as the NM R relaxation data suggest a deeper localization of Patman in the membr ane, sensing a less polar and/or more restricted probe environment.