Kinetics of Cytochrome Oxidation in Skunk Cabbage Mitochondria

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Abstract
Investigations on Symplocarpus foetidus mitochondria resulted in the finding of a small amount of oxidized cytochrome in the presence of high concentrations of respiratory inhibitors and led to a serious consideration of the excess oxidase hypothesis as opposed to the alternate oxidase hypothesis. Subsequently, the hypothesis that an autoxidizable cytochrome b (b7)-mediated respiration of certain plant tissues in the presence of cyanide was rendered more unlikely by the finding that mitochondria isolated from skunk cabbage spadices contained the same carriers that are found generally in higher plant mitochondria. Indeed, there is no cytochrome component that is unique to cyanide-insensitive tissues. However, recent kinetic work has shown the presence of 2 oxidases in higher plant mitochondria, and optical investigations have indicated that the cytochrome a component of plant mitochondria exists in 2 parts which are distinguished by maximal absorption near 602 and 608 m[mu], respectively.