title: Studies of energy-linked reactions. Inhibition of oxidative phosphorylation by DL-8-methyldihydrolipoate.
abstract: 1. DL-8-Methyldihydrolipoate was shown to be a potent inhibitor of mitochondrial oxidative phosphorylation and ATP-driven energy-linked reactions. 2. ADP-stimulated respiration utilizing pyruvate + malate and succinate in both ox heart and rat liver mitochondria is inhibited; oxidative phosphorylation using pyruvate + malate, succinate and ascorbate + NNN'N'-tetramethyl-p-phenylenediamine as substrates is also inhibited; uncoupler-stimulated respiration is unaffected regardless of the substrate used. 3. Mitochondrial oligomycin-sensitive adenosine triphosphatase is inhibited in both the membrane-bound form and the purified detergent-dispersed preparation. 4. ATP-driven transhydrogenase and the ATP-driven energy-linked reduction of NAD+ by succinate in ox heart submitochondrial particles are inhibited, whereas the respiratory-chain-driven transhydrogenase is unaffected. 5. DL-8-Methyl-lipoate has no immediate effect on the above reactions, demonstrating the requirement for the reduced form for inhibition. 6. The inhibitory properties of DL-8-methyldihydrolipoate are analogous to those of oligomycin and provide further evidence of a role for lipoic acid in oxidative phosphorylation.
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002417:Cattle; D006321:Heart / Q000187:drug effects; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D010085:Oxidative Phosphorylation / Q000187:drug effects*; D051381:Rats; D008063:Thioctic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D008063:Thioctic Acid; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases