Deoxyuridine-l’yl radical

The kinetics of the reaction of 2 -deoxyuridin-L-yl radicals (11) with thiols, with superoxide release from the peroxyl radical (13) generated, have been reported. Radical (11) is produced by photolysis of precursor (10). When the radical is produced in the presence of thiols, (12) is formed. Second-order kinetics were found for the reactions with thiols. Peroxyl radical (13) is formed in the presence of oxygen. This undergoes heterolytic fragmentation to the superoxide anion O2 and cation (14), which ultimately leads to 2-deoxyribonolactone (15). 

The repair of carbohydrate radicals vithin polynucleotides can proceed with remarkable stereoselectivity, as demonstrated for hydrogen transfer from both 2-mercaptoethanol and dithiothreitol to deoxyuridin-l -yl radials within single-and double-stranded oligonucleotides (Scheme 3.3, Reactions (3.21a) and (3.21j8)) [56]. 

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