Oxidation of single-stranded oligonucleotides by carbonate radical anions: generating intrastrand cross-links between guanine and thymine bases separated by cytosines.

ABSTRACT: The carbonate radical anion is a biologically important one-electron oxidant that can directly abstract an electron from guanine, the most easily oxidizable DNA base. Oxidation of the 5'-d(CCTACGCTACC) sequence by photochemically generated CO3*- radicals in low steady-state concentrations relevant to biological processes results in the formation of spiroiminodihydantoin diastereomers and a previously unknown lesion. The latter was excised from the oxidized oligonucleotides by enzymatic digestion with nuclease P1 and alkaline phosphatase and identified by LC-MS/MS as an unusual intrastrand cross-link between guanine and thymine. In order to further characterize the structure of this lesion, 5'-d(GpCpT) was exposed to CO3*- radicals, and the cyclic nature of the 5'-d(G*pCpT*) cross-link in w

SUBMITTER: Crean C 

PROVIDER: S-EPMC2241916 | biostudies-literature | 2008 Feb

REPOSITORIES: biostudies-literature