Divalent cation shrinks DNA but inhibits its compaction with trivalent cation
Divalent cation shrinks DNA but inhibits its compaction with trivalent cation
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DOI：
10.1063/1.4950749
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发表时间：
2016-05-28
影响因子：
4.4
通讯作者：
Yoshikawa, Kenichi
中科院分区：
文献类型：
--
作者：
Tongu, Chika;Kenmotsu, Takahiro;Yoshikawa, Kenichi
我们的观察揭示了二价和三价阳离子对巨型DNA（T4 DNA 166 kbp）的高阶结构的影响，通过荧光显微镜。发现二价阳离子Mg（2+）和Ca（2+）抑制由三价阳离子亚精胺（SPD（3+））诱导的DNA压缩。另一方面，在没有SPD（3+）的情况下，二价阳离子导致DNA收缩。作为对照实验，我们已经证实了单价阳离子Na（+）对DNA高级结构的影响最小。我们解释2+和3+阳离子之间的竞争的反离子的平移熵的变化。对于与SPD（3+）的压缩，我们认为由于离子交换的固有的单价阳离子凝聚在一个高度带电的双链DNA，由3+阳离子的平移熵的增加。相反，2+阳离子的存在降低了一价和3+离子之间的离子交换的熵贡献的增益。(C)2016年作者。所有文章内容，除非另有说明，是根据知识共享署名（CC BY）许可证（http：//creativecommons.org/licenses/by/4.0/）。
Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).