4. CRANE, F. L., LESTER, R. L., WIDMER, C. and HATEFI, Y. Studies on the electron transport system XVIII. Isolation of coenzyme Q from beef heart and beef heart mitochondria. Biochim. Biophys. Acta 32: 73-79. 1959. 5. CRANE, F. L., WIDMER, C., LESTER, R. L. and HATEFI, Y. Studies on the electron transport system XV. Coenzyme Q (Q275) and the succinoxidase activity of the electron transport part...

Before any of the eleven possible quinones of azulene were known, predictions were made about their proper— ties on the basis of Hickel, MINDO/3, PPP and ab initio SCF (STO—3G) calculations (3). Four unsubstituted quinones of azulene have now been prepared, and the experimental results obtained so far provide information regarding their stability, reduction potentials, cycloadditions with cyclo...

1. A comparison is made of several procedures for the extraction of tocopherols and isoprenoid quinones from plant tissues. 2. Gradient-elution column chromatography on acid-washed alumina efficiently separates the isoprenoid quinones and tocopherols into groups that can then be assayed spectrophotometrically or, with the tocopherols, separated into their individual components and determined by...

The products of aqueous chlorination reactions of 1-methylnaphthalene, fluorene, dibenzofuran, anthracene, phenanthrene, 1-methylphenanthrene, fluoranthene, and pyrene have been determined. The conditions employed for these reactions approximated those that might be encountered in water treatment facilities. Reactions at pH greater than 6 tended to produce oxygenated products (epoxides, phenols...

When spinach (Spinacia oleracea) chloroplast fragments were lyophilized and extracted with n-heptane, acid-bath phosphorylation was significantly reduced. Phosphorylation could be restored to these chloroplasts, if the extracted material (containing quinones, carotenoids, and other lipids) was added back to dry preparation before rehydration. The results reported suggest it was not quinones whi...

Foods are mixed with saliva in the oral cavity and swallowed. While staying in the stomach, saliva is contentiously provided to mix with the ingested foods. Because a salivary component of nitrite is protonated to produce active nitrous acid at acidic pH, the redox reactions of nitrous acid with phenolic compounds in foods become possible in the stomach. In the reactions, nitrous acid is reduce...

Substantial evidence suggests that catechol estrogen-3,4-quinones react with DNA to form predominantly the depurinating adducts 4-hydroxyestrone (estradiol)-1-N3Ade [4-OHE(1)(E(2))-1-N3Ade] and 4-OHE(1)(E(2))-1-N7Gua. Apurinic sites resulting from these adducts generate critical mutations that can initiate cancer. The paradigm of cancer initiation is based on an imbalance in estrogen metabolism...

We examined the kinetics of single-electron reduction of a large number of structurally diverse quinones and nitroaromatic compounds, including a number of antitumour and antiparasitic drugs, and nitroaromatic explosives by recombinant rat neuronal nitric oxide synthase (nNOS, EC 1.14.13.39), aiming to characterize the role of nNOS in the oxidative stress-type cytotoxicity of the above compound...

Various anti-platelet drugs, including quinones, are being investigated as potential treatments for cardiovascular disease because of their ability to prevent excessive platelet aggregation. In the present investigation 3 naphthoquinones (2,3-dimethoxy-1,4-naphthoquinone [DMNQ], menadione, and 1,4-naphthoquinone [4-NQ]) were compared for their abilities to inhibit platelet aggregation, deplete ...

ortho-Quinones are produced in vivo through the oxidation of catecholic substrates by enzymes such as tyrosinase or by transition metal ions. Neuromelanin, a dark pigment present in the substantia nigra and locus coeruleus of the brain, is produced from dopamine (DA) and norepinephrine (NE) via an interaction with cysteine, but it also incorporates their alcoholic and acidic metabolites. In thi...