Formation of modified cleavage termini from the reaction of chromium(V) with DNA.
Formation of modified cleavage termini from the reaction of chromium(V) with DNA.
复制标题
铬 (V) 与 DNA 反应形成修饰的切割末端。
DOI：
10.1016/s0162-0134(99)00189-0
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发表时间：
1999
影响因子：
3.9
通讯作者：
Sugden,KD
中科院分区：
文献类型：
--
作者：
Sugden,KD
25个碱基的寡核苷酸与高价铬络合物二(2-乙基-2-羟基丁基)氧铬酸(V)(Cr(V)-EHBA)反应，产生弗兰克和碱不稳定的链断裂，这些断裂是序列中性的。弗兰克链断裂的形成依赖于O2，而碱不稳定的链断裂的形成不依赖于O2。在含氧条件下，铬(V)-EHBA与5‘-32P标记的低聚物反应生成了修饰的3’-末端、3‘-磷酸乙醇酸和3’-磷酸末端。3‘-磷酸乙醇酸末端的形成以及反应对O2的依赖性与从DNA的脱氧核糖部分中提取C4’氢原子的机制一致。使用3‘-32P标记的寡聚体的相同反应仅产生与Maxam-Gilbert标记共迁移所指定的5’-磷酸末端。在过氧化氢存在下，铬(V)-EHBA与DNA的反应观察到了类似的裂解曲线和修饰的末端。加入过氧化氢后，DNA裂解反应不依赖于O2，且DNA裂解程度高于单独使用铬(V)-EHBA的裂解水平。这些发现表明，致癌物质铬酸盐的还原中间体铬(V)可以引起DNA损伤，这是一种氧化机制，模拟氧自由基DNA损伤途径。
Reaction of a 25 bp oligonucleotide with the high valent chromium complex, bis(2-ethyl-2-hydroxybutyrato)oxochromate(V) (Cr(V)–EHBA) produced both Frank- and alkali-labile strand breaks that were sequence-neutral. Frank strand break formation was found to be O2-dependent while formation of alkali-labile strand breaks were O2-independent. Reaction of Cr(V)–EHBA with the 5′-32P-labeled oligomer under oxygenated conditions formed the modified 3′-terminus, 3′-phosphoglycolate, as well as the 3′-phosphate terminus. Formation of the 3′-phosphoglycolate termini, and the O2dependence of the reactions were consistent with a mechanism involving abstraction of the C4′ hydrogen atom from the deoxyribose moiety of DNA. Identical reactions using the 3′-32P-labeled oligomer yielded only 5′-phosphate termini as assigned by co-migration with Maxam–Gilbert markers. Analogous cleavage profiles and modified termini were observed for the reaction of Cr(V)–EHBA and DNA in the presence of hydrogen peroxide. With the addition of hydrogen peroxide, the DNA cleavage reactions were O2-independent and the level of DNA cleavage was enhanced over that observed with Cr(V)–EHBA alone. These findings suggest an oxidation mechanism whereby a reductive intermediate of the carcinogen chromate, Cr(V), can cause DNA damage that mimics oxygen radical DNA damaging pathways.