Institut für Chemie, Freie Universität Berlin, Berlin, Germany.
J Phys Chem B. 2011 Jul 7;115(26):8569-74. doi: 10.1021/jp200840j. Epub 2011 Jun 15.
Base pairs formed by the inosine nucleoside (I) play an important role in many physiological processes as well as in various DNA technologies. Relative stabilities and favored base pair geometries of free inosine wobble base pairs in aprotic solvents have been determined through (1)H NMR measurements at room temperature and at very low temperatures in a freonic solvent. As indicated by its significantly deshielded imino proton, the Watson-Crick-type I·C base pair forms a remarkably strong NHN hydrogen bond. For the thermodynamically less stable I·A wobble base pair, two configurations of similar population coexist at 133 K in the slow hydrogen bond exchange regime, namely a Watson-Crick(I)-Watson-Crick(A) geometry and a Watson-Crick(I)-Hoogsteen(A) geometry. I·U base pairs are stabilized by two rather weak hydrogen bonds and are significantly disfavored over inosine self-associates in a low-temperature Freon solution.
肌苷核苷（I）形成的碱基对在许多生理过程以及各种 DNA 技术中都起着重要作用。通过室温下和极低温度下在弗里昂溶剂中的（1）H NMR 测量，确定了无质子溶剂中游离肌苷摆动碱基对的相对稳定性和有利的碱基对几何形状。正如其明显去屏蔽的亚氨基质子所表明的那样，沃森-克里克型 I·C 碱基对形成了非常强的 NHN 氢键。对于热力学上不太稳定的 I·A 摆动碱基对，在慢氢键交换区，133 K 时存在两种具有相似群体的构象共存，即沃森-克里克（I）-沃森-克里克（A）几何和沃森-克里克（I）-Hoogsteen（A）几何。I·U 碱基对由两个相当弱的氢键稳定，并且在低温弗里昂溶液中明显不如肌苷自身缔合。
