Cross-Linked Thymine-Purine Base Tandem Lesions: Synthesis, Characterization, and Measurement in -Irradiated Isolated DNA

详细信息    查看全文

• 作者：Sophie Bellon ; Jean-Luc Ravanat ; Didier Gasparutto ; and Jean Cadet
• 刊名：Chemical Research in Toxicology
• 出版年：2002
• 出版时间：April 2002
• 年：2002
• 卷：15
• 期：4
• 页码：598 - 606
• 全文大小：178K
• 年卷期：v.15,no.4(April 2002)
• ISSN：1520-5010

文摘

5-(Phenylthiomethyl)-2'-deoxyuridine has been recently shown to be a specific photolabileprecursor of 5-(2'-deoxyuridilyl)methyl radical that is involved in the formation of tandem baselesion with vicinal guanine in oxygen-free aqueous solution. The thionucleoside was incorporatedby either liquid or solid-phase phosphoramidite synthesis into dinucleoside monophosphateswith a 2'-deoxyadenosine residue as the vicinal nucleoside located either at the 3' or5'-extremity. UV-C irradiation of the modified dinucleoside monophosphate under anaerobicconditions gives rise to cross-linked thymine^CH2-C8adenine tandem base lesions which wereisolated and characterized by ¹H NMR and mass spectrometry analyses. The formation of thelatter tandem lesions involved an intramolecular addition of the 5-(2'-deoxyuridilyl)methylradical to the C8 of the adenine moiety. A sensitive and specific assay aimed at monitoringthe formation of the four thymine^CH2-C8purine adducts, namely d(TG), d(GT), d(TA),d(AT), within DNA, was designed. This was based on a liquid chromatography analysis coupledto tandem mass spectrometry (HPLC-MS/MS) detection of the dinucleoside monophosphateswhich were quantitatively released from -irradiated DNA and oligodeoxyribonucleotides byenzymatic hydrolysis. The four lesions were detected in both single-stranded oligodeoxyribonucleotide and isolated DNA upon exposure to -radiation in oxygen-free aqueous solution. Itwas found that the tandem guanine-thymine lesions were produced more efficiently than theadenine-thymine cross-links. Moreover, a significant sequence effect was observed. Thus, theyield of formation of the tandem lesions is higher when the purine base is located at the 5'position of the 5-(2'-deoxyuridilyl)methyl radical.