Erythrosin and pH gradient induced photo-voltages in bilayer membranes

Varnadore, W. E.; Arrieta, Rodolfo T.; Duchek, John R.; Huebner, Jay S.

doi:10.1007/bf01870478

Cited by 14 publications

(4 citation statements)

References 35 publications

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“…However, in very few cases have the kinetics been reduced to molecular terms. One example is the observation of fast transient photovoltages in bilayers containing erythrosin, which are attributed to de-and re-protonation of the triplet state of the dye (Varnadore et al, 1982). An early study on the MgOEPbilayer-ferricyanide system showed the decay kinetics could be explained by an apparent second-order reaction of the lipophilic pigment cation formed in the photoreaction with added aqueous ferrocyanide (Hong and Mauzerall, 1974).…”

Section: Introductionmentioning

confidence: 99%

Distributed kinetics of decay of the photovoltage at the lipid bilayer-water interface

Liu¹,

Mauzerall²

1985

Biophysical Journal

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The decay kinetics of the photovoltage formed on pulsed illumination of a chlorophyll a- (chl a-) containing lecithin-bilayer adjacent to a ferricyanide solution on one side show characteristics of a system with distributed rate constants, i.e., the decay approaches linearity in log of time. The kinetics can be explained by a distribution of the chl cation over a few angstroms depth in the interfacial region of the bilayer and a rate constant exponentially dependent on distance as expected from tunneling theory. Addition of the donor ferrocyanide both increases the average rate and sharpens the distribution. There is a competitive inhibition by ferricyanide of the reaction of pigment cation with ferrocyanide. Removal of oxygen increases the rate of decay when an acceptor, methyl viologen or anthraquinone-2-sulfonate, forms oxygen-sensitive radicals. The cation charge does not cross the bilayer on a time scale of less than 0.01 s. These data define a reaction localized precisely in the finite interfacial region of the lipid bilayer-water interface.

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Section: Introductionmentioning

confidence: 99%

Distributed kinetics of decay of the photovoltage at the lipid bilayer-water interface

Liu¹,

Mauzerall²

1985

Biophysical Journal

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“…Many compounds are known that change their pKa's (i.e., become stronger or weaker acids) upon photoexcitation (40,41). Under appropriate conditions, some of the compounds that become stronger acids produce photovoltages by releasing protons near the membrane surface (33). These protons move rapidly into the adjacent aqueous solution.…”

Section: Photoacidificationmentioning

confidence: 99%

Photoelectric effects in lipid bilayer membranes: A pedagogical review

Huebner¹,

Popp²,

Williams³

1988

J. Chem. Educ.

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A study of lipid bilayers that offers a venue for bringing together several areas of chemistry-specifically electrochemistry, kinetics, photochemistry, and surface chemistry. The authors summarize the current knowledge of photoelectric effects in lipid bilayer membranes and give the design for a series of experiments that illustrate the important aspects of both the physical chemistry involved and its biological implications.

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“…The coupling of ATP synthase to bacteriorhodopsin directly gives access to the time resolution achieved in single turnover photoelectric experiments, which is about 2/zsec in photocurrent measurements (Fahr et al, 1981) and may be improved to several nanoseconds in photovoltage experiments (Benz & L~uger, 1976;Varnadore et al, 1982). Measurements on ATP synthase kinetics by means of stopped-flow techniques are limited in time resolution to several milliseconds and detect only the final step in the reaction cycle, the release of synthesized ATP (Smith, Stokes & Boyer, 1976;Homer & Moudrianakis, 1983, 1985, Gr~.ber, Junesch & Schatz, 1984.…”

Section: Flash-induced Charge Displacements In Bacteriorhodopsin/atp mentioning

confidence: 99%

Pump and displacement currents of reconstituted ATP synthase on black lipid membranes

et al. 1988

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Purified ATP synthase (FoFI) from Rhodospirillum rubrum was reconstituted into asolectin liposomes which were than adsorbed to a planar lipid bilayer. After the addition of an inactive photolabile ATP derivative (caged ATP), ATP was released after illumination with UV light, which led to a transient current in the system. The transient photocurrent indicates that the vesicles and the planar membrane are capacitatively coupled. Stationary pump currents were obtained after addition of protonophores. These currents are specifically inhibited by oligomycin and stimulated threefold by inorganic phosphate (P~). In analogy oligomycin-sensitive pump currents in the reverse direction coupled to net ATP synthesis were induced by a light-induced concentration jump of ADP out of caged ADP, demonstrating the reversibility of the pump. For this, a preformed proton motive force and Pi were necessary.In a second series of experiments, proteoliposomes containing both ATP synthase and bacteriorhodopsin were adsorbed to a planar bilayer. The system was excited by a laser flash. The resulting photocurrents were measured with a time resolution of 2/xsec. In the presence of ADP, the signal was modulated by the electrical activity of ATP synthase. ADP-induced charge displacements in ATP synthase, with time constants of 11 and 160 b~sec were obtained. The kinetics of the charge movements were slowed down by F0 specific inhibitors (DCCD or oligomycin) and were totally absent if ADP binding to F~ is prevented by the catalytic site-blocking agent NBD-CI. The charge displacement of ATP synthase is coupled only to the membrane potential induced by the electrical activity of bacteriorhodopsin. The charge movements are interpreted as conformational transitions during early steps of the reaction cycle of ATP synthase.

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Erythrosin and pH gradient induced photo-voltages in bilayer membranes

Cited by 14 publications

References 35 publications

Distributed kinetics of decay of the photovoltage at the lipid bilayer-water interface

Distributed kinetics of decay of the photovoltage at the lipid bilayer-water interface

Photoelectric effects in lipid bilayer membranes: A pedagogical review

Pump and displacement currents of reconstituted ATP synthase on black lipid membranes

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