Formation of globules and aggregates of DNA chains in DNA/polyethylene glycol/monovalent salt aqueous solutions.
Formation of globules and aggregates of DNA chains in DNA/polyethylene glycol/monovalent salt aqueous solutions.
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在 DNA/聚乙二醇/一价盐水溶液中形成 DNA 链的球体和聚集体。
DOI：
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发表时间：
2009
影响因子：
4.4
通讯作者：
H. Watanabe
中科院分区：
文献类型：
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作者：
H. Kawakita;T. Uneyama;M. Kojima;K. Morishima;Yuichi Masubuchi;H. Watanabe
人们已经知道，在反离子和其他聚合物的存在下，巨大的DNA在水溶液中显示出结构转变。然而，这些转变的机制尚未完全理解。在这项研究中，我们直接观察结构的探测（染料标记），稀释的DNA链在未探测的DNA/聚乙二醇（PEG）/一价盐（NaCl）的水溶液与荧光显微镜检查这一机制。具体而言，我们改变PEG分子量和盐浓度，以研究消耗和静电相互作用之间的竞争对线圈-小球过渡和聚集体形成的影响。结果发现，当未探测的DNA链的浓度高于其重叠浓度时，小球与聚集体共存。我们讨论了所观察到的结构的稳定性的基础上的自由能模型，将有吸引力的耗尽能，排斥静电能，和链弯曲能。该模型表明，在高盐浓度下或PEG存在下，小球和聚集体都比无规卷曲更稳定，当耗尽相互作用超过静电相互作用时，发生了转变。然而，从热力学模型中没有推导出小球和聚集体的共存，这表明DNA溶液的非平衡态和这些结构的可分解性。因此，还根据动力学模型分析了小球和聚集体的群体比。分析表明，耗尽的相互作用占主导地位的比例，合理化的小球和聚集体的共存。
It has been known that giant DNA shows structural transitions in aqueous solutions under the existence of counterions and other polymers. However, the mechanism of these transitions has not been fully understood. In this study, we directly observed structures of probed (dye-labeled), dilute DNA chains in unprobed DNA/polyethylene glycol (PEG)/monovalent salt (NaCl) aqueous solutions with fluorescent microscopy to examine this mechanism. Specifically, we varied the PEG molecular weight and salt concentration to investigate the effect of competition between the depletion and electrostatic interactions on the coil-globule transition and the aggregate formation. It was found that the globules coexist with the aggregates when the unprobed DNA chains have a concentration higher than their overlap concentration. We discuss the stability of the observed structures on the basis of a free energy model incorporating the attractive depletion energy, the repulsive electrostatic energy, and the chain bending energy. This model suggested that both of the globules and aggregates are more stable than the random coil at high salt concentrations/under existence of PEG and the transition occurs when the depletion interaction overwhelms the electrostatic interaction. However, the coexistence of the globule and aggregate was not deduced from the thermodynamic model, suggesting a nonequilibrium aspect of the DNA solution and metastabilities of these structures. Thus, the population ratio of globules and aggregates was also analyzed on the basis of a kinetic model. The analysis suggested that the depletion interaction dominates this ratio, rationalizing the coexistence of globules and aggregates.
影响因子：
56.9
作者：
Perkins, TT;Smith, DE;Chu, S
通讯作者：
Chu, S
影响因子：
14.9
作者：
RYE, HS;YUE, S;GLAZER, AN
通讯作者：
GLAZER, AN
影响因子：
4.4
作者：
Ou, ZY;Muthukumar, M
通讯作者：
Muthukumar, M