Complexes between uncouplers of oxidative phosphorylation |
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Authors: | Margaret Foster Stuart McLaughlin |
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Affiliation: | (1) Department of Physiology and Biophysics, Health Sciences Center, State University of New York, 11790 Stony Brook, New York;(2) Present address: Department of Biology, University of California at San Diego, 92037 La Jolla, California |
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Abstract: | Summary We have examined the effects of two weak acid uncouplers of oxidative phosphorylation, 2,4-dinitrophenol and 5,6-dichloro-2-trifluoromethyl-benzimidazole, on the electrical properties of phospholipid bilayer membranes. All the effects they produce are consistent with the charged permeant species being a HA2– complex formed between the neutral acid HA and its anion A– and the current in the aqueous phases being carried by buffered hydrogen ions. When both uncouplers are present simultaneously, all the evidence we have obtained is consistent with the charged permeant species being a HAB– complex formed between the neutral acid HA of one uncoupler and the anion B– of the other. It was necessary, however, to take into account interfacial processes and the unstirred layers adjacent to the membrane, the adsorption of anions to the bilayer and the buffer level in the aqueous phases to explain the results in terms of this model. The degree to which these factors will complicate a comparison of results obtained on artificial systems and mitochondria is also discussed. |
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