6-Ketocholestanol is a recoupler for mitochondria, chromatophores and cytochrome oxidase proteoliposomes
| Autor: | Svetlana E Mansurova, Vladimir P. Skulachev, Inna I. Severina, V.I. Dedukhova, Ruben A. Simonyan, Anatoly A. Starkov, Boris V. Chernyak, Tatyana V. Vygodina, Dmitry A. Bloch |
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| Rok vydání: | 1997 |
| Předmět: |
Male
Protonophore Proteolipids T-Lymphocytes Biophysics Phospholipid Rhodobacter sphaeroides In Vitro Techniques Biochemistry Cytochrome oxidase Membrane Potentials Electron Transport Complex IV Rats Sprague-Dawley chemistry.chemical_compound Adenosine Triphosphate Oxygen Consumption 6-Ketocholestanol Animals Cytochrome c oxidase Recoupler Mitochondrion Ketocholesterols Membrane potential Chromatophore biology Uncoupling Agents Bacterial Chromatophores Cell Biology biology.organism_classification Mitochondria Rats Membrane chemistry Uncoupler Gramicidin biology.protein Cattle |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1318:159-172 |
| ISSN: | 0005-2728 |
| Popis: | The effect of 6-ketocholestanol (kCh) on various natural and reconstituted membrane systems has been studied. 6-ketocholestanol (5 alpha-Cholestan-3 beta-ol-6-one), a compound increasing the membrane dipole potential, completely prevents or reverses the uncoupling action of low concentrations of the most potent artificial protonophore SF6847. This effect can be shown in the rat liver and heart muscle mitochondria, in the intact lymphocytes, in the Rhodobacter sphaeroides chromatophores, and in proteoliposomes with the heart muscle or Rh. sphaeroides cytochrome oxidase. The recoupling effect of kCh disappears within a few minutes after the kCh addition and cannot be observed at all at high SF6847 concentrations. Almost complete recoupling is also shown with FCCP, CCCP, CCP and platanetin. With 2,4-dinitrophenol, fatty acids and gramicidin, kCh is ineffective. With TTFB, PCP, dicoumarol, and zearalenone, low kCh concentrations are ineffective, whereas its high concentrations recouple but partially. The kCh recoupling is more pronounced in mitochondria, lymphocytes and proteoliposomes than in chromatophores. On the other hand, mitochondria, lymphocytes and proteoliposomes are much more sensitive to SF6847 than chromatophores. A measurable lowering of the electric resistance of a planar bilayer phospholipid membrane (BLM) are shown to occur at SF6847 concentrations which are even higher than in chromatophores. In BLMs, kCh not only fails to reverse the effect of SF6847, but even enhances the conductivity increase caused by this uncoupler. It is assumed that action of low concentrations of the SF6847-like uncouplers on coupling membranes involves cytochrome oxidase and perhaps some other membrane protein(s) as well. This involvement is inhibited by the asymmetric increase in the membrane dipole potential, caused by incorporation of kCh to the outer leaflet of the membrane. |
| Databáze: | OpenAIRE |
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