3-[p-(6-phenyl)-1,3,5-hexatrienyl]phenylpropionic acid (PA-DPH): characterization as a fluorescent membrane probe and binding to fatty acid binding proteins.
The negatively charged fluorophore 3-[p-(6-phenyl)-1,3,5-hexatrienyl]phenylpropionic acid (PA-DPH) was characterized by comparison with its parent compound DPH, and with cationic trimethylammonium-DPH (TMA-DPH). The molar absorption coefficient of PA-DPH (60,000 cm-1.mol-1) as well as its quantum yield (0.7) and fluorescence lifetime (5 ns) in fluid phase membranes are intermediate between DPH and TMA-DPH. Steady-state fluorescence polarization studies show that PA-DPH detects the phase transition of both neutral and anionic bilayers. In fluid phase membranes the absolute values of PA-DPH polarization are considerably higher than DPH and somewhat lower than TMA-DPH. The results suggest that like TMA-DPH, PA-DPH is anchored to the surface of the membrane by its charge, but that it is probing a region somewhat deeper along the bilayer normal. PA-DPH binds to rat hepatic fatty acid binding protein (hFABP) and bovine serum albumin at PA-DPH/protein molar ratios of 1.5:1 and at least 6:1, respectively. Native oleic acid competes with PA-DPH for binding to both proteins, suggesting that the two ligands compete for similar binding sites. The affinity of PA-DPH for hFABP is similar to that of oleic acid. Thus, PA-DPH should be useful both as an anionic fluorescent membrane probe and a long-chain free fatty acid analogue.
Trotter
P J
PJ
Department of Nutrition, Harvard School of Public Health, Harvard Medical School, Boston, MA 02115.
Storch
J
J
D002352:Carrier Proteins; D004161:Diphenylhexatriene / Q000031:analogs & derivatives; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005230:Fatty Acids, Nonesterified; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D008563:Membrane Lipids; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D011422:Propionates; D012710:Serum Albumin, Bovine; D013329:Structure-Activity Relationship; D013696:Temperature
D002352:Carrier Proteins; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005230:Fatty Acids, Nonesterified; D005456:Fluorescent Dyes; D008563:Membrane Lipids; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D011422:Propionates; D004161:Diphenylhexatriene; D012710:Serum Albumin, Bovine; C029658:propionic acid