紫外线B区对小牛胸腺DNA损伤的拉曼光谱研究

用拉曼光谱检测了远紫外区UVB(280m～320nm)对小牛胸腺DNA的损伤，并对这个区段紫外线对DNA的不同照射时间时的损伤特征进行了比较分析。实验中所用的紫外线强度与太阳光强度相当。结果表明，辐照3h以内时，UVB对DNA的构型有较明显的损伤，这可能是受到嘧啶碱基损伤的影响。相对而言，UVB对脱氧核糖和碱基的损伤要严厉得多。就碱基对的受损伤程度来说，嘧啶碱受损最严重，部分证明了环丁烷嘧啶二聚体和6-4光产物的形成。经过3h UVB照射，AT碱基对和和胞嘧啶环的堆叠程度有所瓦解，一些碱基对受到修饰。而一些拉曼特征峰强度的反复波动，则说明了长时间的紫外照射可以导致部分DNA光复活的产生。进一步分析发现，UVB以一种较快的方式对DNA产生损伤。

Raman Spectroscopic Study of Damage to Calf Thymus DNA with UVB

Raman spectroscopy is used to detect the influence of isolated UVB radiation on calf thymus DNA in aqueous solution. From the spectra of DNA after UVB radiation for 1 h and 3 h, it is found that the conformation of DNA is just slightly damaged, but the damage to the deoxyribose moiety is much more significant. At the same time, UVB radiation has obvious damage to the base pairs, among which the pyrimidine base pairs are influenced more seriously. After UVB radiation for 3 h, unstacking of the AT base pairs and the cytosine ring takes place and some severe damage to the thymine moiety occurs, and some base pairs have been modified. Consequently, some cyclobutane pyrimidine dimmers (CPDs) and (6-4) photoproducts must have formed. Moreover, with UVB radiation for 3 h, the photoreactivation of DNA occurs. A further analysis shows that UVB damage the Calf Thymus DNA in a fast way.