Cyanide-resistant respiration

In earlier studies [5,6] superoxide detection in mitochondria was equated to hydrogen peroxide formation. However, while it is quite possible that superoxide is a stoichiometric precursor of mitochondrial hydrogen peroxide, it is understandable that the level of hydrogen peroxide may be decreased due to the reactions with various mitochondrial oxidants. Moreover, superoxide level can be underestimated due to the reaction with mitochondrial MnSOD. Several authors [7,8] assumed that mitochondrial superoxide production may be estimated through cyanide-resistant respiration, which supposedly characterizes univalent dioxygen reduction. This method was applied for the measurement of superoxide production under in vitro normoxic and hyperoxic conditions, in spite of the finding [7] that cyanide-resistant respiration reflects also the oxidation of various substrates (lipids, amino acids, and nucleotides). Earlier,... 

Azcon-Bieto, J., J. Murillo, and J. Penuelas. 1987. Cyanide-resistant respiration in photosynthetic organs of freshwater aquatic plants. Plant Physiol. 84 701-706. 

Van De Venter, H.A. 1985. Cyanide-resistant respiration and cold resistance in seedlings of maize (Zea mays L.). Ann. Botany 56 561-563. 

Laties and associates589-592 provided evidence for an alternative, cyanide-resistant path of respiration in avocado mitochondria. Uncouplers were considered to stimulate glycolysis to the point where the glycolytic flux exceeds the oxidative capacity of the cytochrome pathway, with the result that the alternative pathway is engaged. However, these authors concluded that the alternative pathway is not required in order to sustain the elevated rate of respiration that characterizes the climacteric. Clarification of the role, if any, of this alternative pathway in fruit ripening awaits further study. 

Henry, M.F. (1981) Bacterial cyanide-resistant respiration a review, in Cyanide in Biology (eds B. Vermesland, E.E. Conn, C.J. Knowles, J. Westley and F. Wissing). Academic Press, London, pp. 415-36. 

Four types of oxygen consumption occur in plants dark respiration, photorespiration, chloroplast respiration, and cyanide-resistant respiration. Other reviews of photorespiration have been published 41, 42) therefore it will not be discussed here. Also, because knowledge of respiratory ETS in plants is based on the higher plants in contrast to the algae, this section will be confined largely to the higher plant literature. 

Using the P. Infestans-potato tuber system outlined above, ellcltor-Induced accumulation of phytoalexlns has been Inhibited by sallcyl-hydroxamlc acid and dlsulflram (103,109,110) these compounds Inhibit both cyanide-resistant respiration and lipoxygenase enzymes, these latter acting specifically on polyunsaturated fatty acids with a cls-1,4-pentadlene system to form hydroperoxides (111). It has been speculated without further data that lipoxygenase activity may be Involved In eliciting the hypersensitive response In potato tubers... 

Nature and Control of Respiratory Pathways in Plants Ibe Interaction of Cyanide-Resistant Respiration with the Cyanide-Sensitive Pathway... 

The addition of exogenous substrates of primary metabolites to organisms in culture (or blocking of particular steps of biosynthetic pathways) can result in overproduction of either primary or secondary compounds. Gross primary production by plants exceeds net primary production. Additionally as much as 38% of carbon fixed by photosynthesis may be lost through photorespiration. The process of cyanide-resistant respiration represents an obvious nonaccumu-lative mechanism by which plants can divide any overflow into carbon dioxide (Waterman and Mole, 1989). 

Nature and Control of Respiratory Pathways in Plants The Interaction of Cyanide-Resistant Respiration with the Cyanide-Sensitive Pathway David A. Day, Geoffrey P. Anron, and George G. Laties Control of the Krebs Cycle T. Wiskich... 

In another study, cyanide inhibited the oxidation of D- and L-lactate and NADH oxidase activity in membrane particles of P. shermanii (Pritchard and Asmundson, 1980). The oxygen uptake insensitive to the inhibition by 100 iiM KCN amoimted to 30, 15, 80 and 10% of the total oxygen uptake with L-lactate, D-lactate, succinate and NADH as substrates, respectively. Cyanide-resistant respiration is widespread among living organisms. It is attributed to flavoprotein respiration with participation of oxidases resistant to KCN (Beevers, 1961) it is also explained by die presence of a 6-shimt, i.e., a by-pass to oxygen from cytochrome b (see below). 

Veiga A, Arraba9a JD, Loureiro-Dias MC. 2000. Cyanide-resistant respiration is frequent, but confined to yeasts incapable of aerobic fermentation. FEMS Microbiol Lett 190 93-97. 

A. Stelzig, R. D. Allen, and S. K. Bhatia. Inhibition of phytoalexin synthesis in arachidonic acid-stressed potato tissue by inhibitors of lipoxygenase and cyanide-resistant respiration. 

Whereas in animal cells cyanide can virtually completely inhibit oxygen uptake, the respiration of many plant tissues is partially cyanide resistant. The Arum spadix is a classical example and at a particular stage of development may be 90% resistant to the effects of cyanide. This is an extreme example perhaps associated with the ability of the spadix to maintain a temperature above ambient (a factor in the attraction of pollinating flies). However less dramatic examples of cyanide-resistant respiration are common in plants but at present neither the electron pathway nor the metabolic functions of this process are properly understood. 

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