Selective one-electron oxidation of duplex DNA oligomers: reaction at thymines

In DNA duplexes that do not contain guanine, we discovered that reaction occurs primarily at thymine and gives products resulting from oxidation of the T-C5 methyl group and from addition to its C5–C6 double bond

Avik Ghosh; Abraham Joy; Gary B. Schuster; Thierry Douki; Jean Cadet

2008

Scholarcy highlights

  • The one-electron oxidation of duplex DNA generates a nucleobase radical cation that migrates long distances by a hopping mechanism
  • In DNA duplexes that do not contain guanine, we discovered that reaction occurs primarily at thymine and gives products resulting from oxidation of the T-C5 methyl group and from addition to its C5–C6 double bond
  • This surprising result shows that it is the relative reactivity, not the stability, of a nucleobase radical cation that determines the nature of the products formed from oxidation of DNA
  • A mechanism for reaction is proposed whereby a thymine radical cation may either lose a proton from its methyl group or H2O/O2 may add across its double bond
  • Addition may initiate a tandem reaction that converts both thymines of a TT step to oxidation products

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