We have measured the rates of superoxide anion generation by cytochrome bc(1) complexes isolated from bovine heart and yeast mitochondria and by cytochrome bc(1) complexes from yeast mutants in which the midpoint potentials of the cytochrome b hemes and the Rieske iron-sulfur cluster were altered by mutations in those proteins. With all of the bc(1) complexes the rate of superoxide anion produc...

A ubiquinol-cytochrome c oxidoreductase (cytochrome bc1) complex has been purified from the plasma membrane of aerobically grown Paracoccus denitrificans by extraction with dodecyl maltoside and ion exchange chromatography of the extract. The purified complex contains two spectrally and thermodynamically distinct b cytochromes, cytochrome c1, and a Rieske-type iron-sulfur protein. Optical spect...

To investigate the inhibitory action and binding site of a quinone-like molecule, S-undecyl-6-hydroxy-4,7dloxobenzothiazole (UHDBT), a series of 4,?-dioxobenzothiazole derivatives were synthesized and their inhibitory efficiencies studied. Replacing the 6-hydroxyl or 2-hydrogen of UHDBT with a bromo or a methoxy group causes only a slight decrease in inhibitory efficiency, indicating that the 6...

For a number of years, coenzyme Q (CoQ10 in humans) was known for its key role in mitochondrial bioenergetics; later studies demonstrated its presence in other subcellular fractions and in plasma, and extensively investigated its antioxidant role. These two functions constitute the basis on which research supporting the clinical use of CoQ10 is founded. Also at the inner mitochondrial membrane ...

The location of the H+-translocating reactions within energy-conserving Site 2 of the mitochondrial electron transport chain was evaluated from two sets of data. In the first, the H+/2e- ejection ratios and Ca2+/2e- uptake ratios were compared for electron flow from succinate dehydrogenase, whose active site is on the matrix side of the inner membrane and from glycerol phosphate dehydrogenase, ...

Studies in vitro and in mice indicate a role for Coenzyme Q(10) (CoQ(10) ) in gene expression. To determine this function in relationship to physiological readouts, a 2-week supplementation study with the reduced form of CoQ(10) (ubiquinol, Q(10) H(2) , 150 mg/d) was performed in 53 healthy males. Mean CoQ(10) plasma levels increased 4.8-fold after supplementation. Transcriptomic and bioinforma...

Cytochrome b was identified as one of the ubiquinone-binding proteins in bovine heart mitochondrial ubiquinol-cytochrome c reductase by photoaffinity labeling using 3-azido-2-methyl-5-methoxy-6-(3,7-dimethyl[3H]-octyl)-1,4-benzoquinone ([3H]azido-Q). The [3H]azido-Q-labeled cytochrome b protein was purified to homogeneity from the azido-Q-labeled ubiquinol-cytochrome c reductase by a procedure ...

Both apicomplexan parasites Toxoplasma gondii and Plasmodium falciparum lack type I NADH dehydrogenases (complex I) but instead carry alternative (type II) NADH dehydrogenases, which are absent in mammalian cells and are thus considered promising antimicrobial drug targets. The quinolone-like compound 1-hydroxy-2-dodecyl-4(1H)quinolone (HDQ) was recently described as a high-affinity inhibitor o...

Today in industrialized countries cardiovascular diseases are the leading cause of death. In the U.S., a significant increase in the incidence of congestive heart failure (CHF) has been found in the recent years. Researchers at the Henry Ford “Heart and Vascular Institute” in Detroit observed that the annual number of heart failure cases has more than doubled in the period from 1989 to 2012. Al...