HYDROPEROXIDES OF DNA MODEL SYSTEMS IN AQUEOUS-SOLUTION - A RADIATION-CHEMICAL STUDY

The method of acid hydrolysis was applied to the structural identifica tion and the quantification of the yields of the hydroperoxides formed in the gamma-radiolysis of O-2 saturated aqueous solution of di-isopr opyl ether (DIPE), 2,5-dimethyltetrahydrofuran (DMTHF), 2-methyl-2-pro panol (t-butanol), acetone and uracil. All the hydroperoxides have bee n found to undergo a pseudofirst order decomposition in the pH range 3 .5-5.5 and the second order rate constants for the acid catalysed deco mpositon are 3.6 (DIPE), 2.5 and 1.1 (DMTHF), 0.5 (t-butanol), 0.1 (ac etone) and 0.4 (uracil) dm(3) mol(-1) s(-1), at ambient temperature. T he distribution of protonation at the hydroperoxyl O-atoms is 1:1 for the hydroperoxides formed from DIPE and t-butanol while it is 2:1 for acetone and one of the hydroperoxides from DMTHF. The role of O-2(.-) in the formation of these hydroperoxides is discussed. Copyright (C) 1 997 Elsevier Science Ltd