title: Laser photofootprinting of d(C).d(G).d(G) intramolecular triplex.
abstract: Supercoiling-induced structural transition of the d(C24GC21).d(G21CG24) sequence in plasmid DNA in the presence of Mg2+ at neutral pH results in alterations of efficiencies of not only single-quantum (pyrimidine[6-4]pyrimidone adducts) but also two-quantum (alkali-sensitive lesions of dG residues) photomodifications of nucleoside residues within this sequence. The generation of both types of photoreactions was achieved by the application of high-intensity laser UV radiation (intensity approximately 10(11) W/m2, pulse duration approximately 10(-8) s, lambda = 266 nm) for irradiation of a plasmid DNA. The modification extent sufficient for analysis of photoreaction efficiency distributions along both strands of the insert (photofootprinting) was obtained by the action of a single nanosecond pulse of laser UV radiation. The pattern of a laser photofootprinting is consistent with the d(C).d(G).d(G) triplex formation in the presence of Mg2+ within the insert and shows some details of this triplex structure.
authors.affiliation: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow.
authors.forename: O I
authors.initials: OI
authors.lastname: Kovalsky
authors.forename: G A
authors.initials: GA
authors.lastname: Dvoryankin
authors.forename: E I
authors.initials: EI
authors.lastname: Budowsky
mesh_terms: D001483:Base Sequence; D004278:DNA, Superhelical / Q000737:chemistry; D003854:Deoxyribonucleotides / Q000737:chemistry*; D007834:Lasers; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000528:radiation effects; D015183:Restriction Mapping; D014466:Ultraviolet Rays
chemical_list: D004278:DNA, Superhelical; D003854:Deoxyribonucleotides; D046911:Macromolecular Substances