Effects of N,N′-bis-(4-trifluoromethylphenyl)-urea on isolated plant mitochondria and thylakoid membranes - Archive ouverte HAL Access content directly
Journal Articles Phytochemistry Year : 1991

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

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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 μM 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 μM when bovine serum albumin was omitted from the reaction medium. Up to 10 μM, the studied compound acted as a strictly selective uncoupler. At concentrations higher than 10 μM, 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 μM. In thylakoid membranes, the full uncoupling effect was obtained for a concentration of 0.6 μM 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 μM, inhibition of PSII electron transfer was observed. Full inhibition was obtained at 15 μM 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.
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Dates and versions

hal-02713483 , version 1 (19-01-2023)

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Jean-Marc J.-M. Routaboul, Christian Mougin, Patrick Ravanel, Michel Tissut, Georges Mrlina, et al.. Effects of N,N′-bis-(4-trifluoromethylphenyl)-urea on isolated plant mitochondria and thylakoid membranes. Phytochemistry, 1991, 30 (3), pp.733-738. ⟨10.1016/0031-9422(91)85243-S⟩. ⟨hal-02713483⟩
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