Synthesis and fluorescence properties of novel transmembrane probes and determination of their orientation within vesicles

Artikel i vetenskaplig tidskrift, 2000

Two novel transmembrane fluorescent diester probes D and E bearing an anthracenediyl moiety in the middle of the molecule have been synthesized. Their absorption and fluorescence spectra in CHCl3 solution as well as their fluorescence characteristics in dimyristoylphosphatidylcholine (DMPC) large unilamellar vesicles were determined. Although their absorption spectra (first transition, S-0 --> S-1) present a good overlap with the fluorescence spectrum of tryptophan, only probe E could be a good acceptor for the energy-transfer experiments, since a strong overlap exists between the absorption spectrum of tryptophan and the second transition (S-0 --> S-2) of the absorption spectrum of probe D. The Forster critical distance R-0 for energy transfer between tryptophan (donor) and probe E (acceptor) is found to be 23-24 Angstrom. Finally, linear-dichroism studies on shear-deformed DMPC vesicles show the incorporated probe E to lie essentially perpendicular to the bilayer plane. These results establish that probe E could be useful in the study of membrane-bound protein topography by the fluorescence-energy-transfer method.