title: Investigation of excess-electron transfer in DNA double-duplex systems allows estimation of absolute excess-electron transfer and CPD cleavage rates.
abstract: To investigate the parameters and rates that determine excess-electron transfer processes in DNA duplexes, we developed a DNA double-duplex system containing a reduced and deprotonated flavin donor at the junction of two duplexes with either the same or different electron acceptors in the individual duplex substructures. This model system allows us to bring the two electron acceptors in the duplex substructures into direct competition for injected electrons and this enables us to decipher how the kind of acceptor influences the transfer data. Measurements with the electron acceptors 8-bromo-dA (BrdA), 8-bromo-dG (BrdG), 5-bromo-dU (BrdU), and a cyclobutane pyrimidine dimer, which is a UV-induced DNA lesion, allowed us to obtain directly the maximum overall reaction rates of these acceptors and especially of the T=T dimer with the injected electrons in the duplex. In line with previous observations, we detected that the overall dimer cleavage rate is about one order of magnitude slower than the debromination of BrdU. Furthermore, we present a more detailed explanation of why sequence dependence cannot be observed when a T=T dimer is used as the acceptor and we estimate the absolute excess-electron hopping rates.
authors.affiliation: Department of Chemistry and Biochemistry, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, Haus F, 81377 Munich, Germany.
authors.forename: Danila
authors.initials: D
authors.lastname: Fazio
authors.forename: Christian
authors.initials: C
authors.lastname: Trindler
authors.forename: Korbinian
authors.initials: K
authors.lastname: Heil
authors.forename: Chryssostomos
authors.initials: C
authors.lastname: Chatgilialoglu
authors.forename: Thomas
authors.initials: T
authors.lastname: Carell
mesh_terms: D001973:Bromodeoxyuridine / Q000737:chemistry; D002942:Circular Dichroism; D003503:Cyclobutanes / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D004249:DNA Damage; D004260:DNA Repair; D003853:Deoxyribonucleosides / Q000138:chemical synthesis* / Q000737:chemistry; D004583:Electrons; D005415:Flavins / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D011740:Pyrimidine Dimers / Q000737:chemistry*; D012689:Sequence Homology, Nucleic Acid; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D003503:Cyclobutanes; D003853:Deoxyribonucleosides; D005415:Flavins; D011740:Pyrimidine Dimers; D004247:DNA; D001973:Bromodeoxyuridine