title: Metallo-regulation of the bimolecular triplex formation of a peptide nucleic acid.
abstract: Peptide nucleic acid (PNA) conjugates incorporating a bipyridine unit were prepared. The bipyridine was built into the loop moiety of PNAs that were designed to specifically form a hairpin and a PNA/DNA bimolecular triplex. While the thermal stability of the hairpin structure was only minimally affected by Cu(2+) addition, the PNA/DNA bimolecular triplex structure was significantly destabilized by complexation with Cu(2+). The melting temperature of the bimolecular triplex decreased by 17.4 °C in the presence of Cu(2+). This corresponds to more than a 1000 fold decrease in the binding constant for bimolecular triplex formation. Upon complexation, the bipyridine unit underwent a drastic conformational change which accounts for the observed differences in the thermal stabilities of the triplex upon binding. The bipyridine-PNA conjugate may be useful as an allosteric DNA carrier that releases the DNA in response to a certain metal ion concentration.
authors.affiliation: Department of Applied Chemistry and Biochemistry, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan. toshi@chem.kumamoto-u.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shimada
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Sakurai
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kitamura
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Matsuura
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ihara
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D020135:Peptide Nucleic Acids / Q000737:chemistry*
chemical_list: D020135:Peptide Nucleic Acids; C051802:triplex DNA; D015082:2,2'-Dipyridyl; D003300:Copper; D004247:DNA