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Divalent cation shrinks DNA but inhibits its compaction with trivalent cation
The Journal of Chemical Physics ( IF 3.1 ) Pub Date : 2016-05-23 13:47:06 , DOI: 10.1063/1.4950749 Chika Tongu 1 , Takahiro Kenmotsu 1 , Yuko Yoshikawa 2 , Anatoly Zinchenko 3 , Ning Chen 3 , Kenichi Yoshikawa 1
The Journal of Chemical Physics ( IF 3.1 ) Pub Date : 2016-05-23 13:47:06 , DOI: 10.1063/1.4950749 Chika Tongu 1 , Takahiro Kenmotsu 1 , Yuko Yoshikawa 2 , Anatoly Zinchenko 3 , Ning Chen 3 , Kenichi Yoshikawa 1
Affiliation
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.
中文翻译:
二价阳离子使DNA收缩,但抑制了三价阳离子的紧缩
我们的观察通过荧光显微镜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。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,二价阳离子会导致DNA的收缩。作为对照实验,我们已经确认了单价阳离子Na(+)对DNA高阶结构的最小影响。我们根据抗衡离子的平移熵的变化来解释2+和3+阳离子之间的竞争。对于用SPD(3+)压实,我们认为由于在高电荷聚电解质,双链DNA上缩合的固有单价阳离子的离子交换,导致翻译熵的增加,3+阳离子。相反,2+阳离子的存在会降低单价离子与3+离子之间的离子交换所产生的熵贡献。
更新日期:2016-05-24
中文翻译:
二价阳离子使DNA收缩,但抑制了三价阳离子的紧缩
我们的观察通过荧光显微镜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。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,二价阳离子会导致DNA的收缩。作为对照实验,我们已经确认了单价阳离子Na(+)对DNA高阶结构的最小影响。我们根据抗衡离子的平移熵的变化来解释2+和3+阳离子之间的竞争。对于用SPD(3+)压实,我们认为由于在高电荷聚电解质,双链DNA上缩合的固有单价阳离子的离子交换,导致翻译熵的增加,3+阳离子。相反,2+阳离子的存在会降低单价离子与3+离子之间的离子交换所产生的熵贡献。