PARTITION-COEFFICIENTS OF FLUORESCENT-PROBES WITH PHOSPHOLIPID-MEMBRANES

A method for determination of membrane partition coefficients of five fluorescent membraneprobes, 1,6-diphenyl-1,3,5-hexatriene(DPH),p-((6-phenyl)-1,3,5-hexatrienyl)benzoic acid (DPH carboxylic acid), 3-(p-(6-phenyl)-1,3,5-hexatrienyl)phenylpropionic acid (DPH propionic acid),1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene(TMA-DPH) and N4-(4-didecylaminostyryl)-N-methylpyridinium iodide (4-di-10-ASP), was developed utilizing the fluorescence enhancement of a constant probe concentration by titration with excess phospholipid liposomes. The partition coefficients of DPH, DPH carboxylic acid, DPH propionic acid, TMADPH and 4-di-10-ASP into dipalmitoylphosphatidylcholine membranes were determined to be 1.3•106, 1.0•106, 6.5•105, 2.4•105 and 2.8•106 respectively. Knowledge of the partition coefficients may help select a lipid concentration for membrane studies that necessitate a probe's dominant incorporation into membranes. © 1991 Academic Press, Inc.