不同波段紫外光对小牛胸腺DNA损伤的拉曼光谱研究

Comparison of Influences of Different Intervals of Ultraviolet Irradiation on Calf Thymus Studied by Raman Spectroscopy

应用拉曼光谱分波段研究了紫外线对小牛胸腺DNA的损伤特性并对它们的作用特点进行了比较,得到了一个比较完整的紫外损伤机制。结果表明,紫外C(UVC)对DNA产生了全面的损伤,而紫外B(UVB)和紫外A(UVA)对DNA的损伤则具有选择性,其中UVB比UVA的作用速度快。在减少B型DNA构象方面,UVA和UVB似乎要比UVC强。在DNA各基团中,嘧啶碱基和脱氧核糖受损伤最为严重。较长时间的UVA或UVB照射后有光复性现象产生。实验结果部分支持环丁烷嘧啶二聚体(CPD)、6-4光产物(6-4PP)和Dewar异构体的形成。

Raman spectroscopy was used to investigate the effect of different intervals of ultraviolet （UV） to calf thymus DNA in aqueous solution. At the same time, the different influences of these three UV parts were compared, and a complete damaging mechanism of UV to DNA was obtained. The results showed that UVC damages DNA in a complete way, while UVA and UVB damage DNA in a selective way, and the speed effect of UVB on DNA was faster than that of UVA. UVC seemed to be less valid in reducing the B conformation of DNA than UVA and UVB. Among all the groups of DNA, the pyrimidine bases and the deoxyribose experienced the most severe damages. Moreover, with UVA or UVB irradiation for 3 h, the photoreactivation of DNA occured. The experimental results partly supported the formation of several types of dlmeric lesions between adjacent pyrimidine bases, most notably cyelobutane pyrimidine dimers （CPD）, 6-4 photoproducts （6-4PP） and the Dewar valence isomers.