Effect of Electron-Transport Inhibitors on the Generation of Reactive Oxygen Species by Pea Mitochondria during Succinate Oxidation

V. N. Popov^1*, E. K. Ruuge², and A. A. Starkov³

¹Department of Plant Physiology and Biochemistry, Voronezh State University, Universitetskaya pl. 1, Voronezh 394693, Russia; fax: (0732) 78-9755; E-mail: pvn@main.vsu.ru

²Russian Cardiology Research and Production Association, Ministry of Public Health of the Russian Federation, 3-ya Cherepkovskaya ul. 15a, Moscow 121552, Russia; E-mail: ruuge@bior.phys.msu.ru

³Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia; fax: (095) 939-0338; E-mail: stark@izba.ru

^* To whom correspondence should be addressed.

Received May 21, 2002; Revision received July 1, 2002

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The effect of inhibitors of the cytochrome pathway and alternative oxidase on the rate of respiration and generation of reactive oxygen species by pea mitochondria was studied. Respiration of mitochondria from pea cotyledons was inhibited by 70-80% by salicylhydroxamate (SHAM). The rate of hydrogen peroxide production by pea cotyledon mitochondria during succinate oxidation was 0.15 nmol/min per mg protein. SHAM considerably accelerated the hydrogen peroxide production. The SHAM-dependent H₂O₂ production was stimulated by 2 µM antimycin A and inhibited by 5 mM KCN and 1 µM myxothiazol. The study of the rate of O₂^· generation by pea mitochondria using EPR spin traps and epinephrine oxidation showed that H₂O₂ accumulation can be accounted for by a significant increase in the rate of O₂^· production.

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KEY WORDS: reactive oxygen species, mitochondria, electron transport, alternative oxidase, myxothiazol, antimycin A, cyanide

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