title: Elucidation of the Dexter-Type Energy Transfer in DNA by Thymine-Thymine Dimer Formation Using Photosensitizers as Artificial Nucleosides.
abstract: 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.
authors.affiliation: Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany.
authors.forename: Linda
authors.initials: L
authors.lastname: Antusch
authors.affiliation: Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Gaß
authors.affiliation: Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany.
authors.forename: Hans-Achim
authors.initials: HA
authors.lastname: Wagenknecht
mesh_terms: D001577:Benzophenones / Q000737:chemistry; D004249:DNA Damage; D004735:Energy Transfer; D017319:Photosensitizing Agents / Q000737:chemistry*; D011740:Pyrimidine Dimers / Q000737:chemistry* / Q000378:metabolism; D011789:Quantum Theory; D013941:Thymine / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: D001577:Benzophenones; D017319:Photosensitizing Agents; D011740:Pyrimidine Dimers; C549177:4-methylbenzophenone; C569021:4-methoxybenzophenone; D013941:Thymine
keywords: DNA damage; benzophenone; energy transfer; oligonucleotides; triplet energy