Why is the compact state of DNA preferred at higher temperature? Folding transition of a single DNA chain in the presence of a multivalent cation
Why is the compact state of DNA preferred at higher temperature? Folding transition of a single DNA chain in the presence of a multivalent cation
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DOI：
10.1209/epl/i2004-10541-6
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发表时间：
2004-11
期刊：
影响因子：
1.8
通讯作者：
Takuya Saito;Takafumi Iwaki;K. Yoshikawa
中科院分区：
文献类型：
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作者：
Takuya Saito;Takafumi Iwaki;K. Yoshikawa
当加入多价阳离子时，一个巨大的DNA链表现出从伸长的螺旋到折叠的紧凑状态的大的离散转变。我们在四价阳离子（精胺）的存在下，在各种温度和单价盐浓度下进行长DNA的单链观察。我们证实，在较高的温度和较低的一价盐浓度下，紧凑的状态是优选的。这一结果被解释为由于高价和低价离子之间的离子交换，小离子的净平移熵增加。
Upon the addition of multivalent cations, a giant DNA chain exhibits a large discrete transition from an elongated coil into a folded compact state. We performed single-chain observation of long DNAs in the presence of a tetravalent cation (spermine), at various temperatures and monovalent salt concentrations. We confirmed that the compact state is preferred at higher temperatures and at lower monovalent salt concentrations. This result is interpreted in terms of an increase in the net translational entropy of small ions due to ionic exchange between higher and lower valence ions.