Thenoyltrifluoroacetone inhibits succinate-cytochrome c reductase activity of resolved succinate*cytochrome c reductase complex. Dixon plots of [succinate-cytochrome c reductase activity]-’ or [succinateubiquinone reductase activity]-’ versus concentration of inhibitor are consistent with there being a single site of inhibition by thenoyltrifluoroacetone in resolved reductase complex. This agre...

1. It is shown that the electron-transfer inhibitor thenoyltrifluoroacetone abolishes a respiratory-chain electron-paramagnetic-resonance absorbance due to spin-spin interactions of ubisemiquinones at concentrations similar to those required for inhibition of succinate oxidation. 2. A specific site of interaction of thenoyltrifluoroacetone with the respiratory chain is proposed to be on the ubi...

Production of superoxide radical during oxidation of dihydroorotate in rat liver mitochondria was not affected by antimycin A, thenoyltrifluoroacetone, or added ubiquinone but was inhibited by orotate, a product inhibitor of dihydroorotate dehydrogenase. It appears likely that superoxide is generated at the primary dehydrogenase. Dihydroorotate dehydrogenase differs from succinate dehydrogenase...

The extraction of Cu(II), Ni(II), Co(II), Cd(II), Zn(II), Pb(II) and Mn(II) with potassium-dihydro-bispyrazolyl-borate (H(2)BPz(2)(-)) in dichloromethane has been studied. Extraction constants (logK(ex)) have been calculated for all metal systems and were compared with those obtained with dibenzoylmethane (DBM), thenoyltrifluoroacetone (HTTA) and 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP)...