Schweizer Kristina, Léon J Christian, Ravoo Bart Jan, Müller Jens
Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstraße 28/30, 48149 Münster, Germany.
Westfälische Wilhelms-Universität Münster, Organisch-Chemisches Institut, Corrensstraße 40, 48149 Münster, Germany.
J Inorg Biochem. 2016 Jul;160:256-63. doi: 10.1016/j.jinorgbio.2016.03.003. Epub 2016 Mar 16.
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.
采用等温滴定量热法测定了Ag(I)离子与一系列包含咪唑核苷（Im）:咪唑核苷或1,2,4-三唑核苷（Tr）:1,2,4-三唑核苷错配的DNA双链体特异性结合形成金属介导的Im-Ag(I)-Im或Tr-Ag(I)-Tr碱基对（Im = 咪唑核苷；Tr = 1,2,4-三唑核苷）的热力学参数。共讨论了七种不同的双链体，在相邻或非相邻位置包含一到三个人工碱基对。与Tr-Ag(I)-Tr碱基对形成相关的缔合常数估计小于10³ M⁻¹。相比之下，Im-Ag(I)-Im碱基对要稳定得多。其形成的固有缔合常数约为10⁶ M⁻¹，因此大于由天然核碱基组成的T-Hg(II)-T和C-Ag(I)-C碱基对的形成常数。两个相邻的Im-Ag(I)-Im碱基对协同形成，而两个相距较远的Im-Ag(I)-Im碱基对则非协同形成。一般来说，Ag(I)与含Im:Im双链体的特异性结合是由焓驱动的，在大多数情况下还有显著的额外熵贡献。
