Abstract

Addition of the organophosphorous plant growth regulator - melafen to the mitochondria incubation medium resulted in modification of energy thereof. The modification was dose dependent one. The melafen concentrations 2 × 10^-12, 2 ×10^-18 and 2 × 10^-21 Ðœ raised the maximum rates for oxidation of NAD⁺-dependent substrates, elevated the efficiency of oxidative phosphorylation and activated electron transport in the terminal step of mitochondrial respiratory chain. Melafen stimulated electron transport during oxidation of succinate by rat liver mitochondria, but had no effect on the rate of this substrate oxidation by sugar beet root mitochondria, which was an evidence for adaptive properties of the preparation. Water stress resulted in decreasing the maximum rates of oxidation of NAD⁺-dependent substrate and decreasing the electron transport rates at the end of the respiratory chain by 30%. A pretreatment of pea seeds with a 10^-7% solution of melafen led to elimination of differences in energetic of mitochondria of sprouts growing under standard conditions and under conditions of low moisture. By stimulating the activity of NAD⁺-dependent dehydrogenases and activation electron transport in the cytochrome oxidase part of respiratory chain, melafen stimulated energy metabolism in the cells and these effects determine the adaptive properties thereof.

Key words: Cytochrome oxidase, mitochondria, oxidative phosphorylation, respiratory chain.