title: Thermodynamics of the formation of Ag(I)-mediated azole base pairs in DNA duplexes.
abstract: Isothermal titration calorimetry was applied to determine the thermodynamic parameters for the specific binding of Ag(I) ions to a series of DNA duplexes comprising Im:Im or Tr:Tr mispairs to form metal-mediated Im-Ag(I)-Im or Tr-Ag(I)-Tr base pairs (Im=imidazole nucleoside; Tr=1.2,4-triazole nucleoside). A total of seven different duplexes are discussed, incorporating one to three artificial base pairs in neighboring or non-neighboring positions. The association constant related to the formation of Tr-Ag(I)-Tr base pairs is estimated to be <10(3)M(-1). In contrast, Im-Ag(I)-Im base pairs are much more stable. The intrinsic association constant for their formation is in the order of 10(6)M(-1) and is therefore larger than that for the formation of T-Hg(II)-T and C-Ag(I)-C base pairs consisting of natural nucleobases. Two neighboring Im-Ag(I)-Im base pairs form cooperatively, whereas two remotely located Im-Ag(I)-Im base pairs form non-cooperatively. In general, the specific binding of Ag(I) to Im:Im-containing duplexes is enthalpically driven, with a significant additional entropic contribution in most cases.
authors.affiliation: Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstraße 28/30, 48149 Münster, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Schweizer
authors.affiliation: Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstraße 28/30, 48149 Münster, Germany.
authors.forename: J Christian
authors.initials: JC
authors.lastname: Léon
authors.affiliation: Westfälische Wilhelms-Universität Münster, Organisch-Chemisches Institut, Corrensstraße 40, 48149 Münster, Germany.
authors.forename: Bart Jan
authors.initials: BJ
authors.lastname: Ravoo
authors.affiliation: Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstraße 28/30, 48149 Münster, Germany. Electronic address: mueller.j@uni-muenster.de.
authors.forename: Jens
authors.initials: J
authors.lastname: Müller
mesh_terms: D020137:Base Pair Mismatch; D020029:Base Pairing; D002413:Cations, Divalent; D002414:Cations, Monovalent; D004247:DNA / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D007700:Kinetics; D008628:Mercury / Q000737:chemistry*; D008958:Models, Molecular; D009691:Nucleic Acid Denaturation; D013816:Thermodynamics; D014230:Triazoles / Q000737:chemistry*
chemical_list: D002413:Cations, Divalent; D002414:Cations, Monovalent; D007093:Imidazoles; D014230:Triazoles; C045575:1,2,4-triazole; D006046:Gold; C029899:imidazole; D004247:DNA; D008628:Mercury
keywords: DNA; Isothermal titration calorimetry; Metal-mediated base pairs; Nucleobases