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The transmembrane gradient of the dielectric constant influences the DPH lifetime distribution
Author(s) -
Ivo Konopásek,
P. Kvasnička,
Evžen Amler,
Arnošt Kotyk,
G Curatola
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)01138-5
Subject(s) - dielectric , chemistry , analytical chemistry (journal) , membrane , phosphatidylcholine , liposome , fluorescence , constant (computer programming) , biophysics , chromatography , materials science , optics , phospholipid , biochemistry , physics , optoelectronics , computer science , biology , programming language
The fluorescence lifetime distribution of 1,6‐diphenyl‐1,3,5‐hexatriene (DPH) and 1‐[4‐(trimethylamino)phenyll‐6‐phenyl‐1,3,5‐hexatriene (TMA‐DPH) in egg‐phosphatidylcholine liposomes was measured in normal and heavy water. The lower dielectric constant (by ∼12%) of heavy water compared with normal water was employed to provide direct evidence that the drop of the dielectric constant along the membrane normal shifts the centers of the distribution of both DPH and TMA‐DPH to higher values and sharpens the widths of the distribution. The profile of the dielectric constant along the membrane normal was not found to be a linear gradient (in contrast to [1]) but a more complex function. Presence of cholesterol in liposomes further shifted the center of the distributions to higher value and sharpened them. In addition, it resulted in a more gradient‐like profile of the dielectric constant (i.e. linearization) along the normal of the membrane. The effect of the change of dielectric constant on the membrane proteins is discussed.