Formation and dissociation of protonated cytosine?cytosine base pairs in i-motifs by ab initio quantum chemical calculations
Formation and dissociation of protonated cytosine?cytosine base pairs in i-motifs by ab initio quantum chemical calculations
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DOI：
10.1088/1674-1056/23/2/020702
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发表时间：
2014-02
影响因子：
1.7
通讯作者：
Xiaohui Zhang;Ming Li;Yanting Wang;Z. Ouyang
中科院分区：
文献类型：
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作者：
Xiaohui Zhang;Ming Li;Yanting Wang;Z. Ouyang
采用从头算量子化学方法研究了C-C+碱基对在酸性和碱性环境下的形成和解离机理。我们的计算表明，在酸性环境中，胞嘧啶单体首先质子化，然后与未质子化的胞嘧啶单体二聚形成C-C+碱基对；在碱性环境中，质子化的胞嘧啶二聚体首先不质子化，然后解离成两个胞嘧啶单体。此外，分离C-C+碱基对的力与两个胞嘧啶单体之间的距离成反比。这些结果为定性解释实验观察到的i基序的可逆形成和解离提供了微观机制。
Formation and dissociation mechanisms of C-C+ base pairs in acidic and alkaline environments are investigated, employing ab initio quantum chemical calculations. Our calculations suggest that, in an acidic environment, a cytosine monomer is first protonated and then dimerized with an unprotonated cytosine monomer to form a C-C+ base pair; in an alkaline environment, a protonated cytosine dimer is first unprotonated and then dissociated into two cytosine monomers. In addition, the force for detaching a C-C+ base pair was found to be inversely proportional to the distance between the two cytosine monomers. These results provide a microscopic mechanism to qualitatively explain the experimentally observed reversible formation and dissociation of i-motifs.