FORMATION OF CYTOSINE GLYCOL AND 5,6-DIHYDROXYCYTOSINE IN DEOXYRIBONUCLEIC-ACID ON TREATMENT WITH OSMIUM-TETROXIDE
FORMATION OF CYTOSINE GLYCOL AND 5,6-DIHYDROXYCYTOSINE IN DEOXYRIBONUCLEIC-ACID ON TREATMENT WITH OSMIUM-TETROXIDE
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DOI：
10.1042/bj2350531
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发表时间：
1986-04-15
影响因子：
4.1
通讯作者：
BLAKELY, WF
中科院分区：
文献类型：
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作者：
DIZDAROGLU, M;HOLWITT, E;BLAKELY, WF
OsO 4选择性地在DNA中形成胸腺嘧啶乙二醇损伤。在过去，OsO 4处理的DNA已被用作利用碱基切除修复酶如DNA糖基化酶的DNA修复研究的底物。然而，目前还没有关于其他OsO 4诱导的DNA碱基损伤的化学特性的信息。完整的知识，这样的DNA损伤可能是重要的修复研究。使用最近开发的方法在DNA中的氧化性碱基损伤的表征，我们提供的证据形成的胞嘧啶乙二醇和5，6-二羟基胞嘧啶部分，除了胸腺嘧啶乙二醇，在DNA中的治疗与OsO 4。为此，OsO 4处理的DNA样品用甲酸水解，然后三甲基硅烷化，并通过毛细管气相色谱-质谱分析。除了胸苷二醇，5-羟基尿嘧啶（异巴比妥酸），5-羟基胞嘧啶和5，6-二羟基尿嘧啶（异二羟尿酸或二羟尿酸）被确定在OsO 4处理的DNA。研究表明，5-羟基尿嘧啶是由甲酸诱导的胞苷二醇脱氨和脱水形成的，胞苷二醇是DNA中胞苷部分的实际氧化产物。5-羟基胞嘧啶明显由胞嘧啶乙二醇脱水而成，5，6-二羟基尿嘧啶则由5，6-二羟基胞嘧啶脱氨基而成。OsO 4处理的胞嘧啶中存在5-羟基尿嘧啶、尿嘧啶乙二醇和5，6-二羟基尿嘧啶支持了该方案。用甲酸处理OsO 4处理的胞嘧啶导致尿嘧啶二醇完全转化为5-羟基尿嘧啶。这些发现的影响相对于DNA修复的研究进行了讨论。
OsO4 selectively forms thymine glycol lesions in DNA. In the past, OsO4-treated DNA has been used as a substrate in studies from DNA repair utilizing base-excision repair enzymes such as DNA glycosylases. There is, however, no information available on the chemical identity of other OsO4-induced base lesions in DNA. A complete knowledge of such DNA lesions may be of importance for repair studies. Using a methodology developed recently for characterization of oxidative base damage in DNA, we provide evidence for the formation of cytosine glycol and 5,6-dihydroxycytosine moieties, in addition to thymine glycol, in DNA on treatment with OsO4. For this purpose, samples of OsO4-treated DNA were hydrolysed with formic acid, then trimethylsilylated and analysed by capillary gas chromatography-mass spectrometry. In addition to thymidine glycol, 5-hydroxyuracil (isobarbituric acid), 5-hydroxycytosine and 5,6-dihydroxyuracil (isodialuric acid or dialuric acid) were identified in OsO4-treated DNA. It is suggested that 5-hydroxyuracil was formed by formic acid-induced deamination and dehydration of cytosine glycol, which was the actual oxidation product of the cytosine moiety in DNA. 5-Hydroxycytosine obviously resulted from dehydration of cytosine glycol, and 5,6-dihydroxyuracil from deamination of 5,6-dihyroxycytosine. This scheme was supported by the presence of 5-hydroxyuracil, uracil glycol and 5,6-dihydroxyuracil in OsO4-treated cytosine. Treatment of OsO4-treated cytosine with formic acid caused the complete conversion of uracil glycol into 5-hydroxyuracil. The implications of these findings relative to studies of DNA repair are discussed.