The Electron Transfer and Oxidative Phosphorylation System and Cytochrome C Reductase Activity of Mitochondria Isolated from Solanum T Uberosum L.

Abstract

Mitochondria capable of oxidative phosphorylation and respiratory control have been isolated from Solanum tuberosum L. using polyvinylpyrrolidone as a complexing agent for oxidizing compounds formed during cellular disruption. An intermittent low speed centrifugation at 200 x g combined with isolation medium containing mannitol, bovine serum albumin and cysteine proved satisfactory for the sendimentation of starch and separation of functional mitochondria having high protein content.Isolated mitochondria were found to be actively oxidizing substrates such as succinate, malate and pyruvate. The efficiency of oxidative phosporylation approaches the expected maxima. As expressed by the P:O ratio and measured polarographically by oxygen electrode it is 1.6. A similar method of investigation evidenced tight coupling of respiratory activity with oxidative phosphorylation, the rate of which is regulated by adenosine diphosphate. This ratio of respiratory control is found to be 4.1.Some information on the cytochrome components of potato mitochondria is obtained. The activities of DPNH and succinate cytochrome c reductases have been demonstrated. They are found to absolutely require lipids for their normal functioning.Test on storage effect revealed that the best method of preservation for isolated mitochondria from potato is deep freezing in liquid nitrogen.