Alternative Pathway Respiration and Lipoxygenase Activity in Aged Potato Slice Mitochondria ¹ Free

Mitochondrial preparations isolated from aged white potato (Solanum tuberosum L.) slices exhibited classical cyanide-insensitive O₂ uptake which was inhibited by salicylhydroxamic acid and tetraethylthiuram disulfide (disulfiram). These mitochondria also possessed lipoxygenase activity, as determined by O₂ uptake in the presence of 4 millimolar linoleic acid. Purification of the mitochondrial preparation on a continuous Percoll gradient resulted in a large decrease in lipoxygenase activity whereas cyanide-insensitive (disulfiram sensitive) O₂ consumption was still observed. These data indicate that cyanide-insensitive O₂ consumption in mitochondrial preparations isolated from aged white potato slices is of mitochondrial origin and not due to lipoxygenase contamination.