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Kinetic Equivalence of Transmembrane pH and Electrical Potential Differences in ATP Synthesis
ATP synthase is the key player of Mitchell's chemiosmotic theory, converting the energy of transmembrane proton flow into the high energy bond between ADP and phosphate. The proton motive force that drives this reaction consists of two components, the pH difference (ΔpH) across the membrane and...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Society for Biochemistry and Molecular Biology
2012
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3308813/ https://www.ncbi.nlm.nih.gov/pubmed/22253434 http://dx.doi.org/10.1074/jbc.M111.335356 |
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author | Soga, Naoki Kinosita, Kazuhiko Yoshida, Masasuke Suzuki, Toshiharu |
author_facet | Soga, Naoki Kinosita, Kazuhiko Yoshida, Masasuke Suzuki, Toshiharu |
author_sort | Soga, Naoki |
collection | PubMed |
description | ATP synthase is the key player of Mitchell's chemiosmotic theory, converting the energy of transmembrane proton flow into the high energy bond between ADP and phosphate. The proton motive force that drives this reaction consists of two components, the pH difference (ΔpH) across the membrane and transmembrane electrical potential (Δψ). The two are considered thermodynamically equivalent, but kinetic equivalence in the actual ATP synthesis is not warranted, and previous experimental results vary. Here, we show that with the thermophilic Bacillus PS3 ATP synthase that lacks an inhibitory domain of the ϵ subunit, ΔpH imposed by acid-base transition and Δψ produced by valinomycin-mediated K(+) diffusion potential contribute equally to the rate of ATP synthesis within the experimental range examined (ΔpH −0.3 to 2.2, Δψ −30 to 140 mV, pH around the catalytic domain 8.0). Either ΔpH or Δψ alone can drive synthesis, even when the other slightly opposes. Δψ was estimated from the Nernst equation, which appeared valid down to 1 mm K(+) inside the proteoliposomes, due to careful removal of K(+) from the lipid. |
format | Online Article Text |
id | pubmed-3308813 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2012 |
publisher | American Society for Biochemistry and Molecular Biology |
record_format | MEDLINE/PubMed |
spelling | pubmed-33088132012-03-28 Kinetic Equivalence of Transmembrane pH and Electrical Potential Differences in ATP Synthesis Soga, Naoki Kinosita, Kazuhiko Yoshida, Masasuke Suzuki, Toshiharu J Biol Chem Molecular Biophysics ATP synthase is the key player of Mitchell's chemiosmotic theory, converting the energy of transmembrane proton flow into the high energy bond between ADP and phosphate. The proton motive force that drives this reaction consists of two components, the pH difference (ΔpH) across the membrane and transmembrane electrical potential (Δψ). The two are considered thermodynamically equivalent, but kinetic equivalence in the actual ATP synthesis is not warranted, and previous experimental results vary. Here, we show that with the thermophilic Bacillus PS3 ATP synthase that lacks an inhibitory domain of the ϵ subunit, ΔpH imposed by acid-base transition and Δψ produced by valinomycin-mediated K(+) diffusion potential contribute equally to the rate of ATP synthesis within the experimental range examined (ΔpH −0.3 to 2.2, Δψ −30 to 140 mV, pH around the catalytic domain 8.0). Either ΔpH or Δψ alone can drive synthesis, even when the other slightly opposes. Δψ was estimated from the Nernst equation, which appeared valid down to 1 mm K(+) inside the proteoliposomes, due to careful removal of K(+) from the lipid. American Society for Biochemistry and Molecular Biology 2012-03-16 2012-01-17 /pmc/articles/PMC3308813/ /pubmed/22253434 http://dx.doi.org/10.1074/jbc.M111.335356 Text en © 2012 by The American Society for Biochemistry and Molecular Biology, Inc. Author's Choice—Final version full access. Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) applies to Author Choice Articles |
spellingShingle | Molecular Biophysics Soga, Naoki Kinosita, Kazuhiko Yoshida, Masasuke Suzuki, Toshiharu Kinetic Equivalence of Transmembrane pH and Electrical Potential Differences in ATP Synthesis |
title | Kinetic Equivalence of Transmembrane pH and Electrical Potential Differences in ATP Synthesis |
title_full | Kinetic Equivalence of Transmembrane pH and Electrical Potential Differences in ATP Synthesis |
title_fullStr | Kinetic Equivalence of Transmembrane pH and Electrical Potential Differences in ATP Synthesis |
title_full_unstemmed | Kinetic Equivalence of Transmembrane pH and Electrical Potential Differences in ATP Synthesis |
title_short | Kinetic Equivalence of Transmembrane pH and Electrical Potential Differences in ATP Synthesis |
title_sort | kinetic equivalence of transmembrane ph and electrical potential differences in atp synthesis |
topic | Molecular Biophysics |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3308813/ https://www.ncbi.nlm.nih.gov/pubmed/22253434 http://dx.doi.org/10.1074/jbc.M111.335356 |
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