Cyanide-Insensitive Respiration in Plant Mitochondria

Pathways of electron transport have been studied in mitochondria isolated from hypocotyls of etiolated mung bean seedlings and skunk cabbage spadices that show cyanide-resistant respiratory activity. The residual flux through cytochrome c oxidase is shown to be small in comparison with the flux thro...

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Veröffentlicht in:Plant physiology (Bethesda) 1971-02, Vol.47 (2), p.236-245
Hauptverfasser: Bendall, D. S., W. D. Bonner, Jr
Format: Artikel
Sprache:eng
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Zusammenfassung:Pathways of electron transport have been studied in mitochondria isolated from hypocotyls of etiolated mung bean seedlings and skunk cabbage spadices that show cyanide-resistant respiratory activity. The residual flux through cytochrome c oxidase is shown to be small in comparison with the flux through an unidentified alternative oxidase that is known to have a high affinity for oxygen. This alternative oxidase is not a cytochrome. Skunk cabbage and mung bean mitochondria contain cytochromes a and a3 that have absorption peaks differing slightly from those of animal preparations. A slow oxidation-reduction of cytochrome a3-CN has been demonstrated. Cytochromes b undergo oxidation and reduction in the presence of cyanide but play no essential role in the cyanide-resistant pathway. Antimycin inhibits to an extent similar to that of cyanide; the respiratory chain bifurcates on the substrate side of the antimycin-sensitive site. Evidence is presented for the selective inhibition by thiocyanate, α,α'-dipyridyl, and 8-hydroxyquinoline of the alternative oxidase pathway, which may therefore contain a non-heme iron protein.
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.47.2.236