Radicals guanine oxidation

The two overwhelming oxidation products of the purine moiety of dGuo 37 arising from the transformation of guanine radical cations 38 were isolated and identified as 2,2-diamino-4-[(2-deoxy-/l-D-eryfhro-pentofura-nosyl)amino]-5(2H)-oxazolone (41) and its precursor 2-amino-5-[(2-deoxy-... 

Our studies showed that i) substitution of an exocyclic amino group of dG is effective in modulating the chemical properties of dG toward one-electron oxidation, and ii) decomposition of the guanine radical cation was effectively suppressed near dphG. These results indicate that dphG is a prototype of nucleosides functioning as an intrinsic antioxidant of duplex DNA toward one-electron oxidation. 

All researchers in the field, however, agree that the guanine radical cations react with water or oxygen to give oxidative DNA lesions, which are in vivo... 

The guanine radical cation is a weak acid = 3.9) [22]. Therefore deprotonation will depend on the environment. Bachler and Hildenbrand [38] have studied the guanine oxidation product in aqueous solution of 5 -dGMP. The best fit to their EPR spectra seems to be from the radical cation (Gua " ). 

The Guanine Radical as a Key Intermediate in the Formation of Oxidatively Modified Guanine Bases in DNA... 

Shukla LI, Adhikary A, Pazdro R, Sevilla MD (2004) Formation of 8-oxo-guanine radicals in y-irradi-ated DNA Evidence for multiple one-electron oxidations by long range hole transfer. Nucleic Acids Res 32 6565-6574... 

For higher DETA/NO concentrations, the DP voltammogram showed two large oxidation peaks for dGuo and dAdo plus a third peak at a lower potential, Epa — + 0.77 V (Fig. 20.10). This peak is a consequence of the interaction between peroxynitrite radicals and DNA, corresponding to guanine (Gua) oxidation. 

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