Degree Name
MS (Master of Science)
Program
Chemistry
Date of Award
5-2026
Committee Chair or Co-Chairs
Marina Roginskaya
Committee Members
Abbas Shilabin, Scott Kirkby
Abstract
Reactive oxygen species (ROS) from normal metabolism and environmental exposure may cause oxidative DNA damage. Guanine (G) is the most oxidizable nucleobase. One-electron oxidation (OEO) of G in produces guanine radical cation (G•⁺), which deprotonates to form guanyl radical G(-H)•.This radical exists in two tautomeric forms: G(N1-H)• and G(N2-H)•. Dimerization of guanyl radical yields G-G cross-links (D1/D2); a tautomeric form for dimer formation remains elusive. This study presents the first characterization of G• dimerization products from the OEO of 1-MeGuo in acidic medium. Photolysis at 470 nm in the presence of S₂O₈²⁻ and Ru(II)(bpy)₃²⁺ generates two major stereoisomers (D1AW* and D1BW*), which are chemically and structurally analogous to D1; further oxidation of D1W* forms D2W*. HPLC, LC-MS, and ¹H-NMR analyses demonstrated that the exocyclic amino hydrogens (N2) but not the N1 hydrogens are required for D1/D2 analog formation, supporting the hypothesis that the G(N2-H)• tautomer predominates during dimerization.
Document Type
Thesis - unrestricted
Recommended Citation
Braimah, Ibrahim Mr, "Mechanism of Formation of Guanine-Guanine Crosslinks as Products of One-Electron Oxidation of 1-Methylguanosine in Acidic Medium" (2026). Electronic Theses and Dissertations. Paper 4665. https://dc.etsu.edu/etd/4665
Copyright
Copyright by the authors.
