Double-stranded DNA dissociates into single strands when dragged into a poor solvent
Double-stranded DNA dissociates into single strands when dragged into a poor solvent
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当双链 DNA 被拖入不良溶剂中时，会解离成单链
DOI：
10.1021/ja074776c
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发表时间：
2007-11-28
影响因子：
15
通讯作者：
Gaub, Hermann E.
中科院分区：
文献类型：
--
作者：
Cui, Shuxun;Yu, Jin;Gaub, Hermann E.
DNA显示出丰富的生物相关超分子结构，这取决于序列和环境条件。由于缩合作用，将双链DNA(DsDNA)从水中拖入贫乏的溶剂中对双链结构的影响尚不清楚。在这里，我们利用基于原子力显微镜和分子动力学(MD)模拟的单分子技术来研究环境变化过程中DNA结构和力学的变化。我们发现，当dsDNA在一条链上从水中被拉到较差的溶剂中时，两条链就分裂了。这一发现得到了MD模拟的证实，在MD模拟中，dsDNA从水中拖入劣质溶剂中，揭示了水/劣质溶剂界面处链分离的细节。由于DNA的结构是高极性的，所以所有的不良溶剂都表现出相对低极性。我们推测，通过提供低极性(即疏水)微环境来自发解离/裂解dsDNA的原理可能是解旋酶的催化机制之一。
DNA displays a richness of biologically relevant supramolecular structures, which depend on both sequence and ambient conditions. The effect of dragging double-stranded DNA (dsDNA) from water into poor solvent on the double-stranded structure is still unclear because of condensation. Here, we employed single molecule techniques based on atomic force microscopy and molecular dynamics (MD) simulations to investigate the change in structure and mechanics of DNA during the ambient change. We found that the two strands are split apart when the dsDNA is pulled at one strand from water into a poor solvent. The findings were corroborated by MD simulations where dsDNA was dragged from water into poor solvent, revealing details of the strand separation at the water/poor solvent interface. Because the structure of DNA is of high polarity, all poor solvents show a relatively low polarity. We speculate that the principle of spontaneous unwinding/splitting of dsDNA by providing a low-polarity (in other word, hydrophobic) micro-environment is exploited as one of the catalysis mechanisms of helicases.