FORMATION OF AN 8-HYDROXYGUANINE MOIETY IN DEOXYRIBONUCLEIC-ACID ON GAMMA-IRRADIATION IN AQUEOUS-SOLUTION
FORMATION OF AN 8-HYDROXYGUANINE MOIETY IN DEOXYRIBONUCLEIC-ACID ON GAMMA-IRRADIATION IN AQUEOUS-SOLUTION
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DOI：
10.1021/bi00337a032
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发表时间：
1985-01-01
期刊：
影响因子：
2.9
通讯作者：
DIZDAROGLU, M
中科院分区：
文献类型：
--
作者：
DIZDAROGLU, M
描述了在水溶液中通过γ-辐射在DNA、2''-脱氧鸟苷和2''-脱氧鸟苷5''-单磷酸中产生的新型辐射诱导产物，即8-羟基鸟嘌呤残基的分离和表征。为此目的，首先用4种酶的混合物水解经γ-照射的DNA，即DNA酶I、脾和蛇毒核酸外切酶以及碱性磷酸酶。三甲基硅烷化后，通过毛细管气相色谱-质谱分析所得混合物，结果表明存在产物，根据其三甲基硅烷基 (Me3Si) 衍生物的典型碎片离子，将其鉴定为 8-羟基-2''-脱氧鸟苷。然后通过使用反相高效液相色谱分离该产物。从分离产物中获取的紫外和质子核磁共振谱证实了其 Me3Si 衍生物的质谱所暗示的结构。通过MS测定分离产物的Me2Si衍生物的准确分子量。所得值与理论分子量一致在1毫质量单位以内。还测量了8-羟基鸟嘌呤的产率。据信其形成机制涉及OH自由基加成到鸟嘌呤的C-8位，然后自由基加合物被氧化。
Isolation and characterization of a novel radiation-induced product, i.e., the 8-hydroxyguanine residue, produced in DNA, 2''-deoxyguanosine and 2''-deoxyguanosine 5''-monophosphate by .gamma.-irradiation in aqueous solution, are described. For this purpose, .gamma.-irradiated DNA was first hydrolyzed with a mixture of 4 enzymes, i.e, DNase I, spleen and snake venom exonuclease, and alkaline phosphatase. Analysis of the resulting mixture by capillary gas chromatography-mass spectrometry after trimethylsilylation revealed the presence of a product, which was identified as 8-hydroxy-2''-deoxyguanosine on the basis of the typical fragment ions of its trimethylsilyl (Me3Si) derivative. This product was then isolated by using reversed-phase high-peformance liquid chromatography. The UV and proton NMR spectra taken from the isolated product confirmed the structure suggested by the mass spectra of its Me3Si derivatives. The accurate molecular mass of the Me2Si derivatives of the isolated product was determined by MS. The obtained value agreed with the theoretical molecular mass within 1 millimass unit. The yield of 8-hydroxyguanine was also measured. Its mechanism of formation is believed to involve OH radical addition to the C-8 position of guanine followed by oxidation of the radical adduct.