title: A study of triplex formatin of 5'-d-T-(C-T-)2C-(T-)4C-(T-C-)2T with 5'-d-A-(G-A-)2G A hairpin triplex with three T.A.T and three C+.G.C bases triads.
abstract: The UV mixing titration, gel electrophoresis, and CD measurements indicate that oligomers with a basic sequence of 5'-d-T-(C-T-)2C-(T-)4C-(T-C-)2T form a hairpin type triplex with the target 5'-d-A-(G-A-)2G. The stability, measured UV melting temperatures, were studied in aqueous solution as functions of mC (5-methylcytidine) replacement of C, pH (4 to 7), and salt concentrations (up to 1 M). The order of stability is 5'-d-A-(G-A-)2G + 5'-d-T-(C-T-)2C-(T-)4C-(T-C-)2T < 5'-d-A-(G-A-)2G + 5'-d-T-(mC-T-)2mC-(T-)4C-(T-C-)2T approximately 5'-d-A-(G-A-)2G + 5'-d-T-(C-T-)2C-(T-)4 mC-(T-mC-)2T < 5'-d-A-(G-A-)2G + 5'-d-T-(mC-T-)2mC-(T-)4mC-(T-mC-)2T at pH 4. These results indicate that (a) a stable triplex is formed with three T.A.T and three C+.G.C base triads and (b) mC is more effective than C to stablize the triplex formation in acidic condition. Thus, this provides a simple system for further studies of triplex.
authors.affiliation: Institute of Chemistry, Academia Sinica, Taipei, Taiwan.
authors.forename: L M
authors.initials: LM
authors.lastname: Tsay
authors.forename: S B
authors.initials: SB
authors.lastname: Lin
authors.forename: H T
authors.initials: HT
authors.lastname: Tsay
authors.forename: H H
authors.initials: HH
authors.lastname: Chen
authors.forename: L S
authors.initials: LS
authors.lastname: Kan
mesh_terms: D001483:Base Sequence; D003562:Cytidine / Q000031:analogs & derivatives / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D013329:Structure-Activity Relationship
chemical_list: D009838:Oligodeoxyribonucleotides; D012965:Sodium Chloride; D003562:Cytidine; C016568:5-methylcytidine