The Respiratory Chain of Beetroot Mitochondria

Abstract

Mitochondria were isolated from root tissue of red beetroot (Beta vulgaris L.) and the components of the respiratory chain for oxidation of succinate and of reduced diphosphopyridine nucleotide (DPNH) were studied. Succinate, DPNH, ferrocytochrome c, and malate were used as substrates, and 2,6-dichlorophenolindophenol, ferricytochrome c, and oxygen as hydrogen (electron) acceptors. DPNH was oxidized without addition of cytochrome c and malate without addition of DPN. These observations suggest that the respiratory chain was retained intact in the isolated mitochondria. Cytochromes b, C1. and c were identified spectroscopically by the positions of their characteristic ex-absorption bands. The very small amount of cytochrome c present may indicate some loss of this component during isolation of the mitochondria. An absorption band near 600 mp' was attributed to cytochromes (a+a3).