title: Reductive electron transfer in phenothiazine-modified DNA is dependent on the base sequence.
abstract: A new DNA assay has been designed, prepared and applied for the chemical investigation of reductive electron transfer through the DNA. It consists of 5-(10-methyl-phenothiazin-3-yl)-2'-deoxyuridine (Ptz-dU, 1) as the photoexcitable electron injector and 5-bromo-2'-deoxyuridine (Br-dU) as the electron trap. The Ptz-dU-modified oligonucleotides were synthesised by means of a Suzuki-Miyaura cross-coupling protocol and subsequent automated phosphoramidite chemistry. Br-dU represents a kinetic electron trap, since it undergoes a chemical modification after its one-electron reduction that can be analysed by piperidine-induced strand cleavage. The quantification of the strand cleavage yields from irradiation experiments reveals important information about the electron-transfer efficiency. The performed DNA studies focused on the base sequence dependence of the electron-transfer efficiency with respect to the proposal that C*- and T*- act as intermediate electron carriers during electron hopping. From our observations it became evident that excess-electron transfer is highly sequence dependent and occurs more efficiently over T-A base pairs than over C-G base pairs.
authors.affiliation: Technical University Munich, Chemistry Department, Lichtenbergstr. 4, 85747 Garching, Germany.
authors.forename: Clemens
authors.initials: C
authors.lastname: Wagner
authors.forename: Hans-Achim
authors.initials: HA
authors.lastname: Wagenknecht
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D001973:Bromodeoxyuridine / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D003857:Deoxyuridine / Q000031:analogs & derivatives* / Q000737:chemistry; D004583:Electrons; D007700:Kinetics; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009841:Oligonucleotides / Q000138:chemical synthesis / Q000737:chemistry; D010084:Oxidation-Reduction; D010640:Phenothiazines / Q000737:chemistry*
chemical_list: C511996:5-(10-methyl-phenothiazin-3-yl)-2'-deoxyuridine; D009841:Oligonucleotides; D010640:Phenothiazines; D004247:DNA; D001973:Bromodeoxyuridine; C031637:phenothiazine; D003857:Deoxyuridine