Profiling cytosine oxidation in DNA by LC-MS/MS.

Spontaneous and oxidant-induced damage to cytosine is probably the main cause of CG to TA transition mutations in mammalian genomes. The reaction of hydroxyl radical (·OH) and one-electron oxidants with cytosine derivatives produces numerous oxidation products, which have been identified in large part by model studies with monomers and short oligonucleotides. Here, we developed an analytical method based on LC-MS/MS to detect 10 oxidized bases in DNA, including 5 oxidation products of cytosine.

Generation of 2'-deoxyadenosine N6-aminyl radicals from the photolysis of phenylhydrazone derivatives.

Nitrogen-centered radicals are major species generated by the addition of hydroxyl radicals and the one-electron oxidation of adenine derivatives. Aminyl radicals are also generated in the decomposition of adenine chloramines upon reaction of hypochlorite. Here, we report the photochemistry of modified 2'-deoxyadenosine (dAdo) containing photoactive hydrazone substituents as a model to investigate the chemistry of dAdo N(6)-aminyl radicals.