Factors that influence the deoxyribose oxidation assay for Fenton reaction products.
The mechanism of oxidation of deoxyribose to thiobarbituric acid-reactive products by Fenton systems consisting of H2O2 and either Fe2+ or Fe2+ (EDTA) has been studied. With Fe2+ (EDTA), dependences of product yield on reactant concentrations are consistent with a reaction involving OH.. With Fe2+ in 5-50 mM phosphate buffer, yields of oxidation products were much higher and increased with increasing deoxyribose concentration up to 30 mM. The product yield varied with H2O2 and Fe2+ concentrations in a way to suggest competition between deoxyribose and both reactants. Deoxyribose oxidation by Fe2+ and H2O2 was enhanced 1.5-fold by adding superoxide dismutase, even though superoxide generated by xanthine oxidase increased deoxyribose oxidation. These results are not as expected for a reaction involving free OH. or site localized OH. product on the deoxyribose. They can be accommodated by a mechanism of deoxyribose oxidation involving an iron(IV) species formed from H2O2 and Fe2+, but the overall conclusion is that the system is too complex for definitive identification of the Fenton oxidant.
Winterbourn
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CC
Department of Pathology, Christchurch School of Medicine, Christchurch Hospital, New Zealand.
D003855:Deoxyribose; D004492:Edetic Acid; D005609:Free Radicals; D006861:Hydrogen Peroxide; D006878:Hydroxides; D017665:Hydroxyl Radical; D007202:Indicators and Reagents; D007501:Iron; D007700:Kinetics; D010084:Oxidation-Reduction; D013858:Thiobarbiturates
C045076:Fenton's reagent; D005609:Free Radicals; D006878:Hydroxides; D007202:Indicators and Reagents; D013858:Thiobarbiturates; D017665:Hydroxyl Radical; D003855:Deoxyribose; D004492:Edetic Acid; D006861:Hydrogen Peroxide; D007501:Iron; C029684:thiobarbituric acid