Influence of ultraviolet radiation on calf thymus DNA studied by Raman spectroscopy

摘要

In order to assess the mutagenic effects of ultraviolet (UV) and solar irradiation on DNA, Raman spectroscopy is used to investigate the structural changes of calf thymus DNA in aqueous solution after ultraviolet radiation. The damage to DNA induced by UV is usually carried out with a germicidal lamp, which mainly covers the region of UVC. For the sake of making a complete investigation of the damage to DNA by ultraviolet radiation, we use different intervals of UV (UVA, UVB and UVC) to conduct our experiments. Such UV radiation is obtained from a solar UV simulator (SS) made by us, which can be conveniently adjusted to different wavelengths and radiation intensities. From the comparison of the Raman spectra of DNA in aqueous solution before and after ultraviolet radiation, it can be inferred that the UV-C has a serious influence on the DNA molecular conformation and damages the hydrogen bonds and bases, UV-B only damages the DNA molecular structure to some extent while UV-A almost does not play an impact on the DNA molecular conformation. For all the three regions of UV, the damage increases with the elongation of irradiation time and is first observed in pyrimidine-dimer bases and deoxyribose. The experimental results also partly support the formation of several types of dimeric lesions between adjacent pyrimidine bases, most notably cyclobutane pyrimidine dimers (CPDs) and the Dewar valence isomers.