Effects of UV and visible radiation on DNA-final base damage.
Effects of UV and visible radiation on DNA-final base damage.
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DOI：
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发表时间：
1997-11
影响因子：
3.7
通讯作者：
J. Cadet;M. Berger;T. Douki;B. Morin;S. Raoul;J. Ravanat;S. Spinelli
中科院分区：
文献类型：
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作者：
J. Cadet;M. Berger;T. Douki;B. Morin;S. Raoul;J. Ravanat;S. Spinelli
太阳辐射介导的细胞DNA修饰可能涉及几种机制。DNA碱基被太阳光的UVB组分（290-320 nm）直接激发，主要通过氧非依赖性反应，导致形成二聚嘧啶损伤，包括环丁二嘧啶、嘧啶（6-4）嘧啶酮光产物和相关价态杜瓦异构体。此外，胞嘧啶和鸟嘌呤的光激发可能导致分别以相对较小的产率形成6-羟基-5，6-二氢胞嘧啶和8-氧代-7，8-二氢鸟嘌呤。需要内源性光敏剂与氧一起参与的第二种机制是UVA（320-400 nm）和可见光产生的大多数DNA损伤的起源。单线态氧，这是从II型机制，可能是主要参与形成8-氧代-7，8-二氢鸟嘌呤，观察到在分离的和细胞的DNA。然而，可以预期的是，通过芬顿型反应也以较低的效率产生了后一种氧化嘌呤损伤以及DNA链断裂和嘧啶碱基氧化产物。这些机制的更明确的评估将需要进一步的研究，旨在识别和定量不同的DNA光损伤，包括二聚嘧啶光产物和光氧化损伤。
Several mechanisms are likely to be involved in the solar radiation-mediated modifications of cellular DNA. Direct excitation of DNA bases by the UVB component (290-320 nm) of solar light gives rise, mostly through oxygen independent reactions, to the formation of dimeric pyrimidine lesions including cyclobutadipyrimidines, pyrimidine (6-4) pyrimidone photoproducts and related valence Dewar isomers. In addition, photoexcitation of cytosine and guanine may lead to the formation in relatively minor yields of 6-hydroxy-5,6-dihydrocytosine and 8-oxo-7,8-dihydroguanine, respectively. A second mechanism that requires the participation of endogenous photosensitizers together with oxygen is at the origin of most of the DNA damage generated by the UVA (320-400 nm) and visible light. Singlet oxygen, which arises from a type II mechanism, is likely to be mostly involved in the formation of 8-oxo-7,8-dihydroguanine that was observed within both isolated and cellular DNA. However, it may be expected that the latter oxidized purine lesion together with DNA strand breaks and pyrimidine base oxidation products are also generated with a lower efficiency through Fenton type reactions. A more definitive assessment of these mechanisms would require further studies aimed at the identification and quantification of the different DNA photolesions including both dimeric pyrimidine photoproducts and photooxidized lesions.