Mechanisms of DNA Oxidation and Cross-linking
DNA strand breaks, base lesions, and DNA-protein cross-links result from oxidative insult to chromatin. Although detailed mechanistic pathways are being elucidated for the first two of these processes in a number of laboratories, formation of DNA-protein cross-links (DPCs) remains poorly understood at the molecular level. Studies outlined in this proposal build upon recent results showing that 8-oxo-7,8-dihydroguanosine is sensitive to further oxidation by one-electron oxidants leading to a quinonoid intermediate that is nucleophilically trapped to ultimately generate hydantoin products.
Experiments underway include NMR and LC/MS characterization of amino acid and polyamine adducts to nucleosides and to DNA oligomers, and investigation of their mechanisms of formation and chemical stability. Methods are being developed to understand the chemical structures responsible for DNA-protein cross-linking via both DNA oxidation and protein oxidation. Adducts of phenols and catechols to guanosine in DNA have been prepared and analyzed for their ability to mediate further oxidative damage to DNA. The intellectual merit of this work is the formation of a detailed molecular picture of how DNA is oxidized in the presence of reactive species such as protein and polyamine nucleophiles.
Students working on this project are well versed in mechanistic organic chemistry, and gain biotechnical skills in the manipulation of nucleic acids and proteins. Their overall contribution is to our molecular understanding of DNA damage which underlies processes leading to aging, cancer, and neurological disorders.
This project is funded by the National Science Foundation, CHE-0514612.