Inorganic and Organic Chemistry Department, Organic Chemistry Section, and IBUB, University of Barcelona, Martí i Franquès 1-11, 08028, Barcelona, Spain.
Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006, Madrid, Spain.
Sci Rep. 2017 Jun 5;7(1):2772. doi: 10.1038/s41598-017-02723-y.
Incorporation of pseudoisocytidine (psC), a neutral analogue of protonated cytidine, in i-motifs has been studied by spectroscopic methods. Our results show that neutral psC:C base pairs can stabilize i-motifs at neutral pH, but the stabilization only occurs when psC:C base pairs are located at the ends of intercalated C:C stacks. When psC occupies central positions, the resulting i-motifs are only observed at low pH and psC:C or psC:psC hemiprotonated base pairs are formed instead of their neutral analogs. Overall, our results suggest that positively charged base pairs are necessary to stabilize this non-canonical DNA structure.
通过光谱方法研究了质子化胞嘧啶的中性类似物假异胞嘧啶(psC)在 i- 发夹中的掺入。我们的结果表明，中性 psC:C 碱基对可以在中性 pH 下稳定 i- 发夹，但只有当 psC:C 碱基对位于插入的 C:C 堆积的末端时才会发生稳定。当 psC 占据中心位置时，仅在低 pH 下观察到所得的 i- 发夹，并且形成 psC:C 或 psC:psC 半质子化碱基对而不是它们的中性类似物。总体而言，我们的结果表明，正电荷碱基对对于稳定这种非 canonical DNA 结构是必要的。
