The metabolism of [U-(14)C]phenylmercury acetate was studied in the rat. After a single subcutaneous dose a small proportion is excreted unchanged in urine, and a larger amount in bile with some resorption from the gut. The greater part of the dose is broken down in the tissues to yield inorganic mercury which is excreted mainly in faeces, and conjugates of phenol and quinol are excreted in uri...

According to a recently reported metabolic pathway, phenolic A-ring estrogens are metabolized in rat liver microsomes partially to the corresponding quinols by cytochrome P450 isoenzymes. We found that these quinols could, in turn, undergo reduction to regenerate the parent estrogens consumed during the metabolic process. Among the tested endogenous reducing agents, NADH and especially NADPH pr...

Little is known about enzymatic quinone-quinol interconversions in the lipid membrane when compared with our knowledge of substrate transformations by globular enzymes. Here, the smallest example of a quinol dehydrogenase in nature, CymA, has been studied. CymA is a monotopic membrane tetraheme c-type cytochrome belonging to the NapC/NirT family and central to anaerobic respiration in Shewanell...

Quinols (5a-c) generate the corresponding aryloxenium ions (6a-c) reversibly at pH 1.0 (0.1M HClO4, 30C) although they are stable for a duration of at least 2-3 weeks at pH 4.6 and pH 7.1 at 30C. Kinetics of decomposition of the parent quinols has been monitored by HPLC in the presence and absence of a trapping agent, Br. In the presence of Br, both bromo adduct and dienonephenol rearranged pro...

The cause of the failure of the C2H2-C2H4 assay for nitrogen-fixing bacteria growing on lower alkanes was studied. Acetylene was a strong competitive inhibitor of methane oxidation for methane-utilizing bacteria, as well as for the oxidation of lower alkanes by other bacteria, so that energy and reducing power were no longer available for the reduction of acetylene by nitrogenase. Nitrogen-fixi...

A refinement of the protonmotive Q cycle mechanism is proposed in which oxidation of ubiquinol is a concerted reaction and occurs by an alternating, half-of-the-sites mechanism. A concerted mechanism of ubiquinol oxidation is inferred from the finding that there is reciprocal control between the high potential and low potential redox components involved in ubiquinol oxidation. The potential of ...

Pt-based catalysts, because of their outstanding activity for hydrocarbon oxidation, are widely used in the engine-exhaust aftertreatment system to remove emissions. However, CO and NOx present real engine exhausts compete with hydrocarbons active Pt sites, thus inhibit oxidation. In this work, we evaluated inhibition effects NO on isooctane oxidation over a Pt/CeO2 catalyst under simulated con...