title: Pyrrolo-dC Metal-Mediated Base Pairs in the Reverse Watson-Crick Double Helix: Enhanced Stability of Parallel DNA and Impact of 6-Pyridinyl Residues on Fluorescence and Silver-Ion Binding.
abstract: Reverse Watson-Crick DNA with parallel-strand orientation (ps DNA) has been constructed. Pyrrolo-dC (PyrdC) nucleosides with phenyl and pyridinyl residues linked to the 6 position of the pyrrolo[2,3-d]pyrimidine base have been incorporated in 12- and 25-mer oligonucleotide duplexes and utilized as silver-ion binding sites. Thermal-stability studies on the parallel DNA strands demonstrated extremely strong silver-ion binding and strongly enhanced duplex stability. Stoichiometric UV and fluorescence titration experiments verified that a single (2py) PyrdC-(2py) PyrdC pair captures two silver ions in ps DNA. A structure for the PyrdC silver-ion base pair that aligns 7-deazapurine bases head-to-tail instead of head-to-head, as suggested for canonical DNA, is proposed. The silver DNA double helix represents the first example of a ps DNA structure built up of bidentate and tridentate reverse Watson-Crick base pairs stabilized by a dinuclear silver-mediated PyrdC pair.
authors.affiliation: Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstraße 11, 48149 Münster (Germany), Fax: (+49) 251-53406857.|Laboratorium für Organische und Bioorganische Chemie, Institut für Chemie neuer Materialien, Universität Osnabrück, Barbarastraße 7, 49069 Osnabrück (Germany).
authors.forename: Haozhe
authors.initials: H
authors.lastname: Yang
authors.affiliation: Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstraße 11, 48149 Münster (Germany), Fax: (+49) 251-53406857.|Laboratorium für Organische und Bioorganische Chemie, Institut für Chemie neuer Materialien, Universität Osnabrück, Barbarastraße 7, 49069 Osnabrück (Germany).
authors.forename: Hui
authors.initials: H
authors.lastname: Mei
authors.affiliation: Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstraße 11, 48149 Münster (Germany), Fax: (+49) 251-53406857. frank.seela@uni-osnabrueck.de.|Laboratorium für Organische und Bioorganische Chemie, Institut für Chemie neuer Materialien, Universität Osnabrück, Barbarastraße 7, 49069 Osnabrück (Germany). frank.seela@uni-osnabrueck.de.
authors.forename: Frank
authors.initials: F
authors.lastname: Seela
mesh_terms: D020029:Base Pairing; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D005453:Fluorescence; D006571:Heterocyclic Compounds / Q000737:chemistry*; D007477:Ions / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D009705:Nucleosides / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*
chemical_list: D006571:Heterocyclic Compounds; D007477:Ions; D009705:Nucleosides; D011743:Pyrimidines; D011758:Pyrroles; D012834:Silver; D004247:DNA; C030986:pyrimidine
keywords: DNA structures; chain structures; nitrogen heterocycles; nucleosides; silver