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

Christensen, B., Gutweiler, M., Grell, E., Wagner, N., Pabst, R., Dose, K., et al. (1988). Pump and displacement currents of reconstituted ATP Synthase on black lipid membranes. Journal of Membrane Biology, 104, 179-191. doi:10.1007/BF01870929.

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Item Permalink: http://hdl.handle.net/21.11116/0000-0007-9932-4 Version Permalink: http://hdl.handle.net/21.11116/0000-0007-9933-3
Genre: Journal Article

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 Creators:
Christensen, B.1, Author              
Gutweiler, M.2, Author
Grell, Ernst2, Author              
Wagner, N.2, Author
Pabst, R.2, Author
Dose, K.2, Author
Bamberg, Ernst1, Author              
Affiliations:
1Transport Proteins Group, Max Planck Institute of Biophysics, Max Planck Society, ou_3273415              
2Molecular Biophysics Group, Max Planck Institute of Biophysics, Max Planck Society, ou_3264820              

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Free keywords: ATP synthase; bacteriorhodopsin; caged ATP; black lipid membrane; Rhodospirillum rubrum
 Abstract: Purified ATP synthase (F0F1) fromRhodospirillum 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 (Pi). 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 μsec. 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 μsec 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 F1 is prevented by the catalytic site-blocking agent NBD-Cl. 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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Language(s): eng - English
 Dates: 1988-02-281988-09-01
 Publication Status: Published in print
 Pages: 13
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1007/BF01870929
 Degree: -

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Title: Journal of Membrane Biology
  Other : J. Membr. Biol.
Source Genre: Journal
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Publ. Info: New York : Springer-Verlag New York
Pages: - Volume / Issue: 104 Sequence Number: - Start / End Page: 179 - 191 Identifier: ISSN: 0022-2631
CoNE: https://pure.mpg.de/cone/journals/resource/954925415943