The Formation of DNA Sugar Radicals from Photoexcitation of Guanine Cation Radicals

• DOI: 10.1667/rr3167
• Publication Date: 2006-07-17T20:53:12Z
• Authors: Lata I. Shukla; Robert Pazdro; James Huang; Christopher DeVreugd; David Becker; Michael D. Sevilla
• Keywords: Radical ion; Hydroxyl radical

Shukla, L. I., Pazdro, R., Huang, J., DeVreugd, C., Becker, D. and Sevilla, M. The Formation of DNA Sugar Radicals from Photoexcitation Guanine Cation Radicals. Radiat. Res. 161, 582–590 (2004).In this investigation radical formation reaction in γ- irradiated model compounds, we report the conversion guanine cation (one-electron oxidized guanine, G· ) to C1′ sugar another at C3′ or C4′ position (designated C3′·/C4′·) by visible UV photolysis. Electron spin resonance (ESR) spectroscopic investigations were performed on salmon testes as well 5′-dGMP, 3′-dGMP, 2′-deoxyguanosine other nucleosides/nucleotides systems. samples (25– 150 mg/ml D2O) prepared with Tl3 Fe(CN)3−6 electron scavengers. Upon γ irradiation such 77 K, electron-gain path is strongly suppressed predominantly found; after photolysis, fraction increases a concomitant reduction . In systems, 3′- dGMP ·; 5′-dGMP · produced attack Cl·−2 parent nucleotide 7 M LiCl glass. Subsequent photolysis 3′-dGMP (77 K) results C1′· whereas C3′·/C4′·. We propose that result delocalization hole electronically excited base into ring, followed deprotonation specific sites sugar.