Phosphatidylcholines fluorescence

Solubilization of an active H,K-ATPase is also a prerequisite for reconstitution of the enzyme into liposomes. With these H,K-ATPase proteoliposomes it is then possible to study the transport characteristics of pure H,K-ATPase, without the interference of residual protein contamination that is usually present in native vesicular H,K-ATPase preparations. Rabon et al. [118] first reported the reconstitution of choleate or n-octylglucoside solubilized H,K-ATPase into phosphatidylcholine-cholesterol liposomes. The enzyme was reconstituted asymmetrically into the proteoliposomes with 70% of the pump molecules having the cytoplasmic side extravesicular. In the presence of intravesicular K, the proteoliposomes exhibited an Mg-ATP-dependent H transport, as monitored by acridine orange fluorescence quenching. Moreover, as seen with native H,K-ATPase vesicles, reconstituted H,K-... 

FIG. 11 Order parameter variation along acyl chains in red cell ghosts ( ), small unilamellar vesicles of egg phosphatidylcholine (V), and paraffin oil (+), as determined by the fluorescence anisotropy decay of the w-anthroyloxy fatty acid probes. (Reprinted by permission from Ref. 12.)... 

Lipid-protein interactions are of major importance in the structural and dynamic properties of biological membranes. Fluorescent probes can provide much information on these interactions. For example, van Paridon et al.a) used a synthetic derivative of phosphatidylinositol (PI) with a ris-parinaric acid (see formula in Figure 8.4) covalently linked on the sn-2 position for probing phospholipid vesicles and biological membranes. The emission anisotropy decays of this 2-parinaroyl-phosphatidylinositol (PPI) probe incorporated into vesicles consisting of phosphatidylcholine (PC) (with a fraction of 5 mol % of PI) and into acetylcholine receptor rich membranes from Torpedo marmorata are shown in Figure B8.3.1. 

Hresko R. C., Sugar I. P., Barenhoiz Y. and Thompson T. E. (1986) Lateral Diffusion of a Pyrene-Labeled Phosphatidylcholine in Phosphatidylcholine Bilayers/Fluorescence Phase and Modulation Study, Biochemistry 25, 3813-3823. 

Figure 5.4. EfTect of the phase transition on the partition coefficient of 5-DOXYL-decane calculated on the basis of its ability to quench the fluorescence of DPH in dimyristoyl-phosphatidylcholine vesicles. The fluorescence anisotropy of the DPH is also shown. (From Ref. 104, with permission.)...

M. Straume and B. J. Litman, Influence of cholesterol on equilibrium and dynamic bilayer structure of unsaturated acyl chain phosphatidylcholine vesicles as determined from higher order analysis of fluorescence anisotropy decay, Biochemistry 26, 5121-5126 (1987). 

R. A. Parente and B. R. Lentz, Advantages and limitations of l-palmitoyl-l-[[2-[4-(6-phcn l-//Y ( .v-l,3,5-hcxatrienyl (phenyl ]ethyl ]carbonyl ]-3-sn-phosphatidylcholine as a fluorescent membrane probe, Biochemistry 24, 6178-6185 (1985). 

E. Friere, T. Markello, C. Rigell, and P. W. Holloway, Calorimetric and fluorescence characterization of interactions between cytochrome bs and phosphatidylcholine bilayers, Biochemistry 22, 1675-1680 (1983). 

M. Caffrey and G. W. Feigenson, Fluorescence quenching in model membranes. 3. Relationship between calcium adenosinetriphosphatase enzyme activity and the affinity of the protein for phosphatidylcholines with different acyl chain characteristics, Biochemistry 20, 1949-1961 (1981). 

P. L.-G. Chong and T. E. Thompson, Oxygen quenching of pyrene-lipid fluorescence in phosphatidylcholine vesicles, Biophys. J. 47, 613-621 (1985). 

The peptide subunit was easily incorporated into lipid bilayers of liposome, as confirmed by absorption and fluorescence spectroscopy. Formation of H-bonded transmembrane channel structure was confirmed by FT IR measurement, which suggests the formation of a tight H-bond network in phosphatidylcholine liposomes. Liposomes were first prepared to make the inside pH 6.5 and the outside pH 5.5. Then the addition of the peptide to such liposomal suspensions caused a rapid collapse of the pH gradient. The proton transport activity was comparable to that of antibiotics gramicidin A and amphotericin B. 

Phosphatidylinositol containing fluorescent fatty acids has also been prepared [303] by synthesising a phosphatidylcholine containing fluorescent fatty acids and then using a phospholipase D, in the presence of inositol, to effect an ester interchange. 

Liposomes applied on the skin were also investigated for their delivery proprieties to the pilosebaceous units [15,23 28]. The in vitro skin penetration behavior of carboxyfluorescein incorporated in multilamellar liposomes (phosphatidylcholine cholesterol phosphatidylser-ine) and in another four nonliposomal systems (HEPES pH 7.4 buffer 5% propylene glycol 10% ethanol and 0.05% sodium lauryl sulfate) was studied by Lieb et al. [25]. Using two fluorescent techniques the authors found a higher accumulation of the probe within skin follicles when delivered from liposomes [25], Further, in an interesting setup of in vitro and in vivo experiments in mice, Hoffman s group observed liposomal delivery of the active Lac-Z gene and its expression mostly in the hair follicles [26,28]. 

Figure 1 Experimentally determined values of ko obtained employing 3-methylindole as the quencher in homogeneous solvents, plotted as a function of the wavelength of maximum fluorescence intensity (data from Ref. 14). kap values determined in DODAC LUVs ( ) and in dipalmitoyl phosphatidylcholine (DPPC) LUVs (A) have been included. Also are included the experimentally determined value of kap in sodium dodecyl sulfate micelles ( ) and the value of kQ estimated from Eq. (21) ( ).

Aqueous phase (2.7 mm3) was placed in the thin lower compartment of the microcell and the Dil dodecane solution (63 mm3) was added on top of the aqueous layer. Fluorescence of the interfacial Dil was observed in the range of 571-575 nm. The influence of two kinds of surfactants, sodium dodecyl sulfate (SDS) and dimyristoyl phosphatidylcholine (DMPC), on the lateral diffusion dynamics of single molecules at the interface was investigated. DMPC was dissolved in chloroform, and the solution was mixed with pure diethyl ether at a ratio of 1 19 (chloroform diethyl ether) by volume. Pure water was placed in the lower container, and the DMPC solution was subsequently (5 mm3) spread carefully on the water. After evaporation of chloroform and diethyl ether, the Dil dodecane solution was added on the DMPC layer. Since Dil has a high... 

Because the dynamics of phospholipid membranes have been well characterized using AF probes [8-13], fluorescence results obtained with hydrated human SC were compared to aqueous suspensions of unilamellar distearoyl-phosphatidylcholine (DSPC) vesicles. DSPC was also used because its phase transition temperature (55°C) is close to that of SC lipids (65 C). The microenvironment inside DSPC and SC membranes was studied by measuring fluorescence lifetimes, and shifts in emission maxima were compared to excitation maxima (Stokes shifts), along with quenching of a series of AF probes by iodide. Stokes shifts (Av) [6] were calculated as ... 

A multistep reaction pathway leads to polymers 43 and 44 with phosphatidylcholine moieties in the main chain and long alkyl groups in the side chain [122]. These polymers exhibit thermotropic liquid-crystalline behavior. Polyamides 45 were obtained by interfacial polycondensation they are insoluble in any normal solvent [123]. Poly-MPC capped with cholesteryl moieties at one or both polymer ends was prepared by the radical polymerization of MFC initiated with 4,4 -azobis[(3-cholesteryl)-4-cyanopentanoate] in the presence of a chain transfer agent [124]. The self-organization of these polymers was analyzed with fluorescence and NMR measurements. 

Langner M, Hui SW. Merocyanine interaction with phosphatidylcholine bilayers. Biochim. Biophys. Acta. 1993 1149 175-179. Ross E, Bedlack RS, Loew EM. Dual-wavelength ratiometric fluorescence measurement of the membrane dipole potential. Biophys. J. 1994 67 208-216. 

Non-Forster fluorescence quenching of trans-etiochlorin by magnesium oc-taethylporphine in phosphatidylcholine vesicles gives evidence for a statistical pair energy trap. Energy transfer also occurs in the excited singlet manifold of chlorophyll. " The photophysics of bis(chlorophyll)-cyclophanes, models of photosynthetic reaction centres, have been explored for use in artificial photosynthesis.Picosecond time-resolved energy transfer in phycobilosomes have also been studied with a tunable laser. The effect of pH on photoreaction cycles of bacteriorhodopsin, " the fluorescence polarization spectra of cells, chromatophores, and chromatophore fractions of Rhodospirillum rubrum, and a brief review of the mechanism and application of artifical photosynthesis are all relevant to the subject of this Chapter. 

Figure 5. (a) Profile of the hydrophobic barrier in a phosphatidylcholine liposome. The circles are measured points based upon the polarity index [54] the solid line is the dielectric constant as determined with fluorescent probes [55]. (b) Calculated relative free energy for diffusion of CH across a dimyristoylphosphatidylcholine bilayer (adapted from [57h]). In both diagrams, distances are measured from the center of the bilayer. 

Fig. 40. Fluorescence decay curves recorded at different emission wavelengths for TNS bound to liposomes of egg yolk phosphatidylcholine at 20 C...

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