Boullard A, Giacomoni P U
Laboratoire de Recherches Fondamentales de L'Oreal, Aulnay-Sous-Bois, France.
J Photochem Photobiol B. 1988 Dec;2(4):491-501. doi: 10.1016/1011-1344(88)85078-4.
Double-stranded, covalently closed, supercoiled circular DNA from phage fd (replicative form) was irradiated with increasing doses of UV light at 254 nm, 290 nm, 313 nm and 365 nm, and subjected to electrophoresis on agarose slab gels. Increasing the doses of UV light at 254 and 290 nm promotes a smooth reduction in the electrophoretic mobility of the sample, as would be expected if the major effect of light at these two wavelengths were to induce the formation of photoproducts leading to the unwinding of the double strand. At high doses, UV light at 290 nm introduces single-strand breaks (1.2 kJ m-2 per nick per million phosphodiester bonds). UV light at 313 nm promotes an abrupt change in the electrophoretic mobility, as would be expected if the effect of this wavelength were to induce single-strand breaks, leading to the transformation of the supercoiled molecules in their relaxed form (23 kJ m-2 in order to introduce one nick per million phosphodiester bonds). UV light at 365 nm also promotes single-strand breaks in DNA (140 kJ m-2 per nick per million phosphodiester bonds).
用254nm、290nm、313nm和365nm的紫外线以递增剂量照射噬菌体fd的双链、共价闭合、超螺旋环状DNA（复制型），并在琼脂糖平板凝胶上进行电泳。在254nm和290nm处增加紫外线剂量会使样品的电泳迁移率平稳下降，正如预期的那样，如果这两个波长的光的主要作用是诱导光产物的形成从而导致双链解旋。在高剂量下，290nm的紫外线会引入单链断裂（每百万磷酸二酯键每切口1.2kJ m-2）。313nm的紫外线会使电泳迁移率发生突然变化，正如预期的那样，如果该波长的作用是诱导单链断裂，导致超螺旋分子转变为松弛形式（每百万磷酸二酯键引入一个切口需要23kJ m-2）。365nm的紫外线也会促进DNA中的单链断裂（每百万磷酸二酯键每切口140kJ m-2）。
