Uncoupling of Oxidative Phosphorylation of Rat Liver Mitochondria by Chinoform

1. Chinoform (5-chloro-7-iodo-8-quinolinol) uncoupled the oxidative phosphorylation of rat liver mitochondria in the presence of Mg ions. 2. Release of the controlled respiration was induced by chinoform both in the presence and absence of inorganic phosphate, and was insensitive to oligomycin. ATPase activity of intact mitochondria was induced by chinoform in the presence of Mg ions, and was inhibited by oligomycin. These data indicate that chinoform affects the “non-phosphorylated high-energy intermediate.” 3. Prior addition of Mg ions was essential for the uncoupling action of chinoform. Chinoform-Mg chelate uncoupled oxidative phosphorylation in the absence of Mg ions. Mg ions could be replaced by other cations such as Fe ions. 4. Chinoform glucuronide (5-chloro-7-iodo-8-quinolyl-β-D-glucuronic acid) had no uncoupling action.