Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany.
Angew Chem Int Ed Engl. 2017 Jan 24;56(5):1385-1389. doi: 10.1002/anie.201610065. Epub 2016 Dec 27.
C-nucleosides of 4-methylbenzophenone, 4-methoxybenzophenone, and 2'-methoxyacetophenone were synthetically incorporated as internal photosensitizers into DNA double strands. This structurally new approach makes it possible to study the distance dependence of thymidine dimer formation because the site of photoinduced triplet energy transfer injection is clearly defined. The counterstrands to these modified strands lacked the phosphodiester bond between the two adjacent thymidines that are supposed to react with each other. Their dimerization could be evidenced by gel electrophoresis because the covalent connection by cyclobutane formation between the two thymidines changes the mobility. A shallow exponential distance dependence for the formation of thymidine dimers over up to 10 A-T base pairs was observed that agrees with a Dexter-type triplet-triplet energy transfer mechanism. Concomitantly, a significant amount of photoinduced DNA crosslinking was observed.
4-甲基二苯甲酮、4-甲氧基二苯甲酮和 2'-甲氧基苯乙酮的 C-核苷被合成性地掺入 DNA 双链作为内部光敏剂。这种结构上的新方法使得研究胸腺嘧啶二聚体形成的距离依赖性成为可能，因为光诱导三重态能量转移注入的位点被明确定义。这些修饰链的互补链缺乏两个相邻胸腺嘧啶之间的磷酸二酯键，而这两个胸腺嘧啶应该相互反应。它们的二聚化可以通过凝胶电泳来证明，因为两个胸腺嘧啶之间通过环丁烷形成的共价连接改变了迁移率。在高达 10 个 A-T 碱基对的范围内，观察到胸腺嘧啶二聚体形成的浅指数距离依赖性，这与 Dexter 型三重态-三重态能量转移机制一致。同时，还观察到大量的光诱导 DNA 交联。
