Hydroxyl ion addition to one-electron oxidized thymine: unimolecular interconversion of C5 to C6 OH-adducts.

ABSTRACT: In this work, addition of OH(-) to one-electron oxidized thymidine (dThd) and thymine nucleotides in basic aqueous glasses is investigated. At pHs ca. 9-10 where the thymine base is largely deprotonated at N3, one-electron oxidation of the thymine base by Cl(2)(•-) at ca. 155 K results in formation of a neutral thyminyl radical, T(-H)·. Assignment to T(-H)· is confirmed by employing (15)N substituted 5'-TMP. At pH ≥ ca. 11.5, formation of the 5-hydroxythymin-6-yl radical, T(5OH)·, is identified as a metastable intermediate produced by OH(-) addition to T(-H)· at C5 at ca. 155 K. Upon further annealing to ca. 170 K, T(5OH)· readily converts to the 6-hydroxythymin-5-yl radical, T(6OH)·. One-electron oxidation of N3-methyl-thymidine (N3-Me-dThd) by Cl(2)(•-) at ca. 155 K produces the cation r

SUBMITTER: Adhikary A 

PROVIDER: S-EPMC3616772 | biostudies-literature | 2013 Feb

REPOSITORIES: biostudies-literature