Tandem base lesions are generated by hydroxyl radical within isolated DNA in aerated aqueous solution
Tandem base lesions are generated by hydroxyl radical within isolated DNA in aerated aqueous solution
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DOI：
10.1021/ja994282i
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发表时间：
2000-05-17
影响因子：
15
通讯作者：
Cadet, J
中科院分区：
文献类型：
--
作者：
Bourdat, AG;Douki, T;Cadet, J
本文报道了N-(2-deoxy-beta-D-erythro-pentofuranosyl)formylamine-8-oxo-7，8-dihydro-2‘-deoxyguanosine(d-βF-8-oxodGuo)和8-oxodGuo-d-beta F两种碱基损伤在羟基自由基作用下的形成。开发了一种特殊的酶处理方法来定量地将串联损伤作为二核苷酸单磷酸从DNA中释放出来。然后，用液相色谱-电喷雾电离串联质谱仪对水解物DNA样品进行分析。采用准确、灵敏的多反应监测技术，在阴性模式下对两个邻近病变同时进行测量。为此，监测了伪分子离子[M-H](-)碎裂产生的两个特征离子。研究发现，在辐照DNA中，dβF-8-oxodGuo和8-oxodGuo-dβF损伤都是(OH)-O-的重要组成部分。自由基引起的碱基损伤。有趣的是，8-oxodGuo-dβF的产量比反向序列损伤要高得多。8-oxodGuo参与的其他串联病变的形成也提供了间接证据，但这些证据仍未完全确定。从DNA光敏化、铁存在下的伽马射线照射和Fenton试剂暴露等几个实验中获得了对DNA损伤形成机理的见解。这使得提出的dβF-8-oxodGuo和8-oxodGuo-d beta F串联碱基损伤的形成途径得以完善。
The hydroxyl radical-mediated formation of two tandem base lesions within DNA including N-(2-deoxy-beta-D-erythro-pentofuranosyl)formylamine-8-oxo-7,8-dihydro-2'-deoxyguanosine (d beta F-8-oxodGuo) and and 8-oxodGuo-d beta F is reported in this study. A specific enzymatic processing was developed to quantitatively release the tandem lesions as dinucleoside monophosphates from DNA. Then, the resulting hydrolyzed DNA samples were analyzed using liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The simultaneous measurement of the two vicinal lesions was performed in the negative mode using the accurate and sensitive multiple reaction monitoring technique. For this purpose, two characteristic ions arising from the fragmentation of the pseudo-molecular ion [M - H](-) were monitored. Both d beta F-8-oxodGuo and 8-oxodGuo-d beta F damage were found to be generated in gamma-irradiated DNA as a significant fraction of (OH)-O-. radical-induced base damage. Interestingly, 8-oxodGuo-d beta F was produced in a much higher yield than the reversed sequence lesion. Indirect evidence is provided for the formation of other tandem lesions involving 8-oxodGuo, but that still remain to be fully identified. Insights into the mechanism of formation of the DNA damage were gained from several experiments including DNA photosensitization, gamma-irradiation in the presence of iron, and exposure to Fenton reagents. This allowed refinement of the proposed pathways for the formation of d beta F-8-oxodGuo and 8-oxodGuo-d beta F tandem base damage.