Oxidative interactions between fatty acid peroxy radicals and quinones: possible involvement in cyanide-resistant electron transport in plant mitochondria.

The interactions between duroquinol, linoleic acid, and lipoxygenase have been followed spectrophotometrically in the uv (210-340 nm) in a simple reaction medium (5 mM [4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid] buffer, pH 6.0). Duroquinol is oxidized by reacting with the peroxy radicals of linoleic acid generated in the presence of lipoxygenase. This oxidation is insensitive to cyanide but is sensitive to salicylhydroxamic acid, propylgallate, and disulfiram, the known inhibitors of lipoxygenase and of the cyanide-resistant electron transport pathway of plant mitochondria. This reaction is proposed as a model for the functioning of this pathway in plant mitochondria.