Biochemical identification of a hydroperoxide derivative of the free 8-oxo-7,8-dihydroguanine base.
Biochemical identification of a hydroperoxide derivative of the free 8-oxo-7,8-dihydroguanine base.
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DOI：
10.1016/j.freeradbiomed.2011.11.015
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发表时间：
2012-02-15
影响因子：
7.4
通讯作者：
Boldogh, Istvan
中科院分区：
文献类型：
--
作者：
Hajas, Gyorgy;Bacsi, Attila;Aguilerra-Aguirre, Leopoldo;German, Peter;Radak, Zsolt;Sur, Sanjiv;Hazra, Tapas K.;Boldogh, Istvan
8-氧代-7，8-二氢鸟嘌呤是原核和真核DNA中最丰富的碱基损伤之一。在哺乳动物细胞中，它在DNA碱基切除修复过程中被8-氧代鸟嘌呤DNA糖基化酶（OGG 1）切除，产生的游离8-oxoG碱基（8-oxoG）是生物样品中氧化应激的DNA衍生生物标志物之一。在核苷和DNA的背景下，8-oxoG的修饰一直是许多研究的主题;然而，游离8-oxoG碱基的氧化转化尚未被描述。通过使用生物化学和细胞生物学测定，我们表明，在分子氧的存在下，游离的8-oxoG碱转化为高活性的氢过氧化物（8-oxoG*）。具体来说，8-oxoG* 将Amplex Red氧化为试卤灵，将H2 DCF氧化为DCF，将Fe 2+氧化为Fe 3+，将GSH氧化为GSSG。这种属性的8-oxoG* 减少了治疗与过氧化氢酶，谷胱甘肽过氧化物酶，但不是超氧化物歧化酶。通过还原剂或氮气气氛防止8-氧代G * 形成。其添加到H2 DCF-DA负载的细胞中迅速增加细胞内DCF荧光。对于8-氧代脱氧鸟苷、2，6-二氨基-4-羟基-5-甲酰胺基嘧啶、2 '-脱氧鸟苷、鸟嘌呤、腺嘌呤、鸟苷和8-羟基腺嘌呤，未观察到此类性质。这些数据表明，一个自由的8-oxoG基地是更容易氧化比它的核苷形式，因此，它的立场是独特的完整和氧化修饰的嘌呤。
8-Oxo-7,8-dihydroguanine is one the most abundant base lesions in pro- and eukaryotic DNA. In mammalian cells, it is excised by the 8-oxoguanine DNA glycosylases (OGG1) during DNA base excision repair, and the generated free 8-oxoG base (8-oxoG) is one of the DNA-derived biomarkers of oxidative stress in biological samples. The modification of 8-oxoG in the context of nucleoside and DNA has been the subject of many studies; however, the oxidative transformation of the free 8-oxoG base has not been described. By using biochemical and cell biological assays, we showed that in the presence of molecular oxygen, the free 8-oxoG base transformed to a highly reactive hydroperoxide (8-oxoG*). Specifically, 8-oxoG* oxidizes Amplex Red to resorufin, H2DCF to DCF, Fe2+ to Fe3+, and GSH to GSSG. This property of 8-oxoG* was diminished by treatment with catalase, glutathione peroxidase, but not superoxide dismutase. 8-oxoG* formation was prevented by reducing agents or nitrogen atmosphere. Its addition to H2DCF-DA-loaded cells rapidly increased intracellular DCF fluorescence. There were no such properties observed for 8-oxodeoxyguanosine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine, 2’-deoxyguanosine, guanine, adenine, guanosine and 8-hydroxyadenine. These data imply that a free 8-oxoG base is more susceptible to oxidation than is its nucleoside form and, consequently, it stands as unique among intact and oxidatively modified purines.
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影响因子：
4.4
作者：
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通讯作者：
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影响因子：
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