title: Synthesis and photooxidation of oligodeoxynucleotides containing 5-dimethylaminocytosine as an efficient hole-trapping site in the positive-charge transfer through DNA duplexes.
abstract: We have designed and synthesized DNA duplexes containing 5-dimethylaminocytosine ((DMA)C) to investigate the effects of C(5)-substituted cytosine bases on the transfer and trapping of positive charge (holes) in DNA duplexes. Fluorescence quenching experiments revealed that a (DMA)C base is more readily one-electron oxidized into a radical cation intermediate as compared with other natural nucleobases. Upon photoirradiation of the duplexes containing (DMA)C, the photosensitizer-injected hole migrated through the DNA bases and was trapped efficiently at the (DMA)C sites, where an enhanced oxidative strand cleavage occurred by hot piperidine treatment. The (DMA)C radical cation formed by hole transfer may undergo specific hydration and subsequent addition of molecular oxygen, thereby leading to its decomposition followed by a predominant strand cleavage at the (DMA)C site. This remarkable property suggests that the modified cytosine (DMA)C can function as an efficient hole-trapping site in the positive-charge transfer in DNA duplexes.
authors.affiliation: Advanced Biomedical Engineering Research Unit, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan. yamada.hisatsugu.3r@kyoto-u.ac.jp
authors.forename: Hisatsugu
authors.initials: H
authors.lastname: Yamada
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kurata
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Tanabe
authors.forename: Takeo
authors.initials: T
authors.lastname: Ito
authors.forename: Sei-ichi
authors.initials: S
authors.lastname: Nishimoto
mesh_terms: D001483:Base Sequence; D003596:Cytosine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D004247:DNA / Q000138:chemical synthesis / Q000737:chemistry*; D004583:Electrons; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D055668:Photochemical Processes
chemical_list: D009838:Oligodeoxyribonucleotides; D003596:Cytosine; D004247:DNA