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Titolo:
DUAL-WAVELENGTH RATIOMETRIC FLUORESCENCE MEASUREMENT OF THE MEMBRANE DIPOLE POTENTIAL
Autore:
GROSS E; BEDLACK RS; LOEW LM;
Indirizzi:
UNIV CONNECTICUT,CTR HLTH,SCH MED,DEPT PHYSIOL,263 FARMINGTON AVE FARMINGTON CT 06030 UNIV CONNECTICUT,CTR HLTH,SCH MED,DEPT PHYSIOL FARMINGTON CT 06030
Titolo Testata:
Biophysical journal
fascicolo: 1, volume: 67, anno: 1994,
pagine: 208 - 216
SICI:
0006-3495(1994)67:1<208:DRFMOT>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
PLANAR LIPID BILAYERS; CHARGE-SHIFT PROBES; ELECTROSTATIC POTENTIALS; ELECTROCHROMIC MECHANISM; PHLORETIN ANALOGS; SURFACE-CHARGES; K+ CHANNEL; BINDING; PROTEINS; CONDUCTANCE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
52
Recensione:
Indirizzi per estratti:
Citazione:
E. Gross et al., "DUAL-WAVELENGTH RATIOMETRIC FLUORESCENCE MEASUREMENT OF THE MEMBRANE DIPOLE POTENTIAL", Biophysical journal, 67(1), 1994, pp. 208-216

Abstract

The electrostatic potentials associated with cell membranes include the transmembrane potential (Delta psi), the surface potential (psi(S)), and the dipole potential (psi(D)). psi(D), which originates from oriented dipoles at the surface of the membrane, rises steeply just within the membrane to similar to 300 mV. Here we show that the potential-sensitive fluorescent dye ta[2-(di-n-octylamino)-6-naphthyl]vinyl]pyridinium betaine (di-8-ANEPPS) can be used to measure changes in the intramembrane dipole potential. Increasing the content of cholesterol and 6-ketocholestanol (KC), which are known to increase psi(D) in the bilayer, results in an increase in the ratio, R, of the dye fluorescence excited at 440 nm to that excited at 530 nm in a lipid vesicle suspension; increasing the content of phloretin, which lowers psi(D), decreases R. Control experiments show that the ratio is insensitive to changesin the membrane's microviscosity. The lack of an isosbestic point in the fluorescence excitation and emission spectra of the dye at variousconcentrations of KC and phloretin argues against 1:1 chemical complexation between the dye and KC or phloretin. The macromolecular nonionic surfactant Pluronic F127 catalyzes the insertion of KC and phloretininto lipid vesicle and cell membranes, permitting convenient and controlled modulation of dipole potential. The sensitivity of R to psi(D) is 10-fold larger than to Delta psi, whereas it is insensitive to changes in psi(S). This can be understood in terms of the location of the dye chromophore with respect to the electric field profile associated with each of these potentials. These results suggest that the gradientin dipole potential occurs over a span less than or equal to 5 Angstrom, a short distance below the membrane-water interface. These approaches are easily adaptable to study the influence of dipole potentials on cell membrane physiology.

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Documento generato il 19/09/20 alle ore 07:36:22