The protonmotive force (Δp) across the mitochondrial inner membrane drives ATP synthesis. In addition, the energy stored in Δp can be dissipated by proton leak through the inner membrane, contributing to basal metabolic rate and thermogenesis. Increasing mitochondrial proton leak pharmacologically should decrease the efficiency of oxidative phosphorylation and counteract obesity by enabling fatty acids to be oxidised with decreased ATP production. While protonophores such as 2,4-dinitrophenol (DNP) increase mitochondrial proton leak and have been used to treat obesity, a slight increase in DNP concentration above the therapeutically effective dose disrupts mitochondrial function and leads to toxicity. Therefore we set out to develop a less toxic protonophore that would increase proton leak significantly at high Δp but not at low Δp. Our design concept for a potential self-limiting protonophore was to couple the DNP moiety to the lipophilic triphenylphosphonium (TPP) cation and this was achieved by the preparation of 3-(3,5-dinitro-4-hydroxyphenyl)propyltriphenylphosphonium methanesulfonate (MitoDNP). TPP cations accumulate within mitochondria driven by the membrane potential (Δψ), the predominant component of Δp. Our hypothesis was that MitoDNP would accumulate in mitochondria at high Δψ where it would act as a protonophore, but that at lower Δψ the accumulation and uncoupling would be far less. We found that MitoDNP was extensively taken into mitochondria driven by Δψ. However MitoDNP did not uncouple mitochondria as judged by its inability to either increase respiration rate or decrease Δψ. Therefore MitoDNP did not act as a protonophore, probably because the efflux of deprotonated MitoDNP was inhibited.
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Review Article|
August 18 2006
Targeting Dinitrophenol to Mitochondria: Limitations to the Development of a Self-limiting Mitochondrial Protonophore
Frances H. Blaikie;
Frances H. Blaikie
1Department of Chemistry, University of Otago, P O Box 56, Dunedin, New Zealand
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Stephanie E. Brown;
Stephanie E. Brown
2Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 2XY, UK
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Linda M. Samuelsson;
Linda M. Samuelsson
1Department of Chemistry, University of Otago, P O Box 56, Dunedin, New Zealand
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Martin D. Brand;
Martin D. Brand
2Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 2XY, UK
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Robin A. J. Smith;
Robin A. J. Smith
1Department of Chemistry, University of Otago, P O Box 56, Dunedin, New Zealand
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Michael P. Murphy
Michael P. Murphy
2Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 2XY, UK
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Publisher: Portland Press Ltd
Online ISSN: 1573-4935
Print ISSN: 0144-8463
© 2006 Springer Science+Business Media, Inc.
2006
Biosci Rep (2006) 26 (3): 231–243.
Citation
Frances H. Blaikie, Stephanie E. Brown, Linda M. Samuelsson, Martin D. Brand, Robin A. J. Smith, Michael P. Murphy; Targeting Dinitrophenol to Mitochondria: Limitations to the Development of a Self-limiting Mitochondrial Protonophore. Biosci Rep 18 August 2006; 26 (3): 231–243. doi: https://doi.org/10.1007/s10540-006-9018-8
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