Cyanide-insensitive Respiration in Plant Mitochondria
Year: 1971
Type: article
Abstract: 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 a(3) that have absorption peaks differing slightly from those of animal preparations. A slow oxidation-reduction of cytochrome a(3)-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, alpha, alpha'-dipyridyl, and 8-hydroxyquinoline of the alternative oxidase pathway, which may therefore contain a non-heme iron protein.
Source: PLANT PHYSIOLOGY
DOI: 10.1104/pp.47.2.236
Authors: D. S. Bendall, W. D. Bonner
Institution: University of Pennsylvania
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2148428115