Park S Y, Harries D, Gelbart W M
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569 USA.
Biophys J. 1998 Aug;75(2):714-20. doi: 10.1016/S0006-3495(98)77561-7.
Under a wide variety of conditions, the addition of condensing agents to dilute solutions of random-coil DNA gives rise to highly compact particles that are toroidal in shape. The size of these condensates is remarkably constant and is largely independent of DNA molecular weight and basepair sequence, and of the nature of condensing agent (e.g., multivalent cation, polymers, or added cosolvent). We show how this optimum size is determined by the interactions between topological defects, which unavoidably strain the circumferentially wound DNA strands in the torus.
在各种各样的条件下，向无规卷曲DNA的稀溶液中添加凝聚剂会产生高度致密的环形颗粒。这些凝聚物的大小非常恒定，并且在很大程度上与DNA分子量、碱基对序列以及凝聚剂的性质（例如多价阳离子、聚合物或添加的助溶剂）无关。我们展示了这种最佳尺寸是如何由拓扑缺陷之间的相互作用决定的，这些拓扑缺陷不可避免地会使环形中沿圆周缠绕的DNA链产生应变。
