Generation of Guanine–Thymine Cross-Links in Human Cells by One-Electron Oxidation Mechanisms

• Published in: Chemical research in toxicology Vol. 26; no. 7; pp. 1031 - 1033
• Main Authors: Madugundu, Guru S, Wagner, J. Richard, Cadet, Jean, Kropachev, Konstantin, Yun, Byeong Hwa, Geacintov, Nicholas E, Shafirovich, Vladimir
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 15.07.2013
• Subjects: Cross-Linking Reagents - chemistry; DNA - chemistry; DNA - genetics; DNA Damage; Electrons; Free Radicals - chemistry; Guanine - chemistry; HeLa Cells; Humans; Hydrogen-Ion Concentration; Lasers; Molecular Structure; Oxidation-Reduction; Thymine - chemistry
• ISSN: 0893-228X; 1520-5010
• DOI: 10.1021/tx400158g

The one-electron oxidation of cellular DNA in cultured human HeLa cells initiated by intense nanosecond 266 nm laser pulse irradiation produces cross-links between guanine and thymine bases (G*-T*), characterized by a covalent bond between C8 guanine (G*) and N3 thymine (T*) atoms. The DNA lesions were quantified by isotope dilution LC-MS/MS methods in the multiple reaction-monitoring mode using isotopically labeled [15N, 13C]-nucleotides as internal standards. Among several known pyrimidine and 8-oxo-7,8-dihydroguanine lesions, the G*-T* cross-linked lesions were detected at levels of ∼0.21 and 1.19 d(G*-T*) lesions per 106 DNA bases at laser intensities of 50 and 280 mJ/cm2/pulse, respectively.