Journal Article

EPR Studies on 6-Benzoylaminopurine and Thenoyltrifluoroacetone Inhibition Sites of Succinate Dehydrogenase in Plant Mitochondria

Michèle Chauveau and Jean Roussaux

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 37, issue 7, pages 914-921
Published in print October 1996 | ISSN: 0032-0781
e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/oxfordjournals.pcp.a029039
EPR Studies on 6-Benzoylaminopurine and Thenoyltrifluoroacetone Inhibition Sites of Succinate Dehydrogenase in Plant Mitochondria

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6-Benzoylaminopurine (BOAP) inhibits succinate oxidation at the level of complex II (succinate-ubiquinone reductase) in the respiratory chain of plant mitochondria. In order to identify its site of action, the effects of BOAP on mitochondrial membranes of potato tubers were studied using electron paramagnetic resonance (EPR), and compared to those of thenoyltrifluoroacetone (TTFA), an inhibitor of complex II. Under aerobic conditions, BOAP induced no change in the EPR signal of the Fe-S center S-3 of succinate dehydrogenase (SDH), unlike TTFA which decreased the height and modified the spectrum of the signal. In the presence of ferricyanide (FeCN), BOAP weakly enhanced the S-3 signal whereas TTFA changed only its shape but not its height. Under anaerobic conditions, center S-1 was completely reduced in the presence of BOAP, while in the presence of TTFA center S-1 was less reduced than in the control, and the center S-3 signal was not different from that under aerobic conditions. Reoxidation of anaerobic preparations was obtained by O2 or FeCN addition. Oxygen was ineffective as an oxidant in the presence of either inhibitor, but a partial reoxidation of center S-3 was obtained with FeCN in the presence of BOAP. These observations point to two different sites for TTFA and BOAP. Both inhibitors act on the O2 side of center S-3, BOAP interfering with the environment of the Fe-S cluster of S-3, while TTFA would act on the cluster itself.

Keywords: Cytokinins; EPR; Plant mitochondria; Solanum tuberosum; Succinate dehydrogenase; Thenoyltrifluoroacetone

Journal Article.  0 words. 

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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