Effects of carbon dioxide on the oxidation of succinate and reduced diphosphopyridine nucleotide by Ricinus mitochondria

Publisher Website
Google Scholar
Abstract
The rates of 3 reactions con-cerned in the oxidation of succinate and reduced diphosphopyridine nucleotide by Ricinus mitochondria were determined in reaction mixtures in equilibrium with various concentrations of CO2 at pH 7.4 and 25[degree] Succinic-cytochrome c reductase was markedly inhibited by relatively low concentrations of CO2-bicarbonate but only slightly by corresponding concentrations of NaCl. The inhibition was competitive with respect to succinate concentration. For this and other reasons it is inferred that the CO2-sensitive component of the reductase is succinic dehydro-genase. Reduced diphosphopyridine nucleotide-cytochrome c reductase was inhibited by high concentrations of sodium bicarbonate and other salts. Cytochrome c oxidase was stimulated by low concentrations and inhibited by high concentration of sodium bicarbonate and other salts. The results have been discussed in relation to the observed effects of CO on the oxidation of succinate and other acids by intact mitochondria and 2 the effects of CO2 in the environment around intact plant tissues.