Oxidase enzymes radical

Many natural products are produced by the coupling of two or more phenolic systems, in a process readily rationalized by means of radical reactions. The reactions can be brought about by oxidase enzymes,... 

The flavones and catechins seem to be the most powerful flavonoids for protecting the body against ROS. Epicatechin and rutin are also powerful free-radical scavengers. Xanthine oxidase enzyme is a source of oxygen-free radicals. The scavenging ability of rutin, quercetin, and silibin may be due to its inhibitory effect on xanthine oxidase activity, thereby resulting in decreased oxidative injury [60]. 

Evidences have confirmed that bisbibenzyls can be produced by the coupling of two phenolic systems by means of free-radical reactions. These reactions can be mediated by oxidase enzymes. C-C bonds involving positions ortho or para to the original phenols, or ether linkages, may be formed in coupling of two of these bibenzyl structures [105]. A previous hypothesis for the biogenesis of... 

D-Glucose Oxidases.—The radical produced aerobically in the reaction catalysed by D-glucose oxidase reduced oxidized Cytochrome C, and additional evidence was presented for the formation of hydrogen peroxide in the enzyme-catalysed reaction. ... 

These include the mitochondrial respiratory chain, key enzymes in fatty acid and amino acid oxidation, and the citric acid cycle. Reoxidation of the reduced flavin in oxygenases and mixed-function oxidases proceeds by way of formation of the flavin radical and flavin hydroperoxide, with the intermediate generation of superoxide and perhydroxyl radicals and hydrogen peroxide. Because of this, flavin oxidases make a significant contribution to the total oxidant stress of the body. 

Oxidation is initiated by formation of radicals which may be the result of enzyme catalysed reactions like oxygen activation by xanthine oxidase in... 

Brass, C.A., Narciso, J. and GoUan, J.L. (1991). Enhanced activity of the free radical producing enzyme xanthine oxidase in hypoxic rat liver. J. Clin. Invest. 87, 424—431. 

Administration of synthetic antioxidants and/or chelating agents that suppress iron ion-dependent free-radical reactions. Some enzyme inhibitors may be appropriate here, for example, xanthine oxidase inhibitors. 

In the original rapid-freezing work on xanthine oxidase (53) it was found that in experiments employing about 1 mole of xanthine per mole of enzyme and an excess of oxygen, the time sequence of appearance of the various EPR signals was molybdenum (V), followed by flavin semi-quinone radical (FADH), followed by iron. This suggested that the electron transfer sequence might be ... 

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