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Effects of N,N'-bis-(4-trifluoromethylphenyl)-urea on isolated plant mitochondria and thylakoid membranes

Routaboul, Jean-Marc and Mougin, Christian and Ravanel, Patrick and Tissut, Michel and Merlina, Georges and Camlon, Jean-Pierre Effects of N,N'-bis-(4-trifluoromethylphenyl)-urea on isolated plant mitochondria and thylakoid membranes. (1991) Phytochemistry, 30 (3). 733-738. ISSN 0031-9422

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Official URL: http://dx.doi.org/10.1016/0031-9422(91)85243-S

Abstract

The N,N'-bis-(4-trifluoromethylphenyl)-urea is demonstrated to be a powerful uncoupler of ATP formation in plant mitochondria and thylakoid membranes. In mitochondria, the full uncoupling effect was obtained at a concentration of 3 micromole uncoupling agent in the medium, which corresponded to an inner mitochondrial concentration of 7.2 nmol uncoupling agent mg-1 protein. The full uncoupling concentration was displaced from 3 to 0.6 micromole when bovine serum albumin was omitted from the reaction medium. Up to 10 micromole, the studied compound acted as a strictly selective uncoupler. At concentrations higher than 10 micromole, a selective inhibition of electron transfer occurred at the level of the external NADH dehydrogenase of the inner mitochondrial membrane; the I50 value was 25 micromole. In thylakoid membranes, the full uncoupling effect was obtained for a concentration of 0.6 micromole uncoupling agent in the medium, which corresponded to a concentration of 25 nmol uncoupling agent mg-1 chlorophyll. The addition of bovine serum albumin (0.1%) to the reaction medium reversed this effect. For concentrations greater than 2 micromole, inhibition of PSII electron transfer was observed. Full inhibition was obtained at 15 micromole uncoupling agent and corresponded to 650 nmol uncoupling agent mg-1 chlorophyll. In marked contrast with classical uncouplers such as CCCP (m-chlorophenylhydrazone) or substituted phenols, the N,N'-bis-(4- trifluoromethylphenyl)-urea cannot be classified among the protonophoric class of uncouplers, due to its inability to exchange protons at pHs between 2 and 9. Its uncoupling action must therefore be attributed either to conformational changes of a transmembrane protein present both in mitochondria and in thylakoid membranes, or to a modification of the arrangement of the phospholipid membrane bilayers.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com/science/article/pii/003194229185243S
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Other partners > Université Joseph Fourier Grenoble 1 - UJF (FRANCE)
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Deposited By: Nadia Kelmouss
Deposited On:21 Jan 2013 07:58

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