Department of Physics, Technical University of Munich, 85747 Garching, Germany.
Phys Rev Lett. 2010 Nov 12;105(20):208101. doi: 10.1103/PhysRevLett.105.208101. Epub 2010 Nov 11.
We present a theoretical framework for the thermodynamic properties of supercoiling-induced denaturation bubbles in circular double-stranded DNA molecules. We explore how DNA supercoiling, ambient salt concentration, and sequence heterogeneity impact on the bubble occurrence. An analytical derivation of the probability distribution to find multiple bubbles is derived and the relevance for supercoiled DNA discussed. We show that in vivo sustained DNA bubbles are likely to occur due to partial twist release in regions rich in weaker AT base pairs. Single DNA plasmid imaging experiments clearly demonstrate the existence of bubbles in free solution.
我们提出了一个理论框架，用于研究圆形双链 DNA 分子中超螺旋诱导的变性泡的热力学性质。我们探讨了 DNA 超螺旋、环境盐浓度和序列异质性如何影响泡的出现。我们推导出了找到多个泡的概率分布的解析推导，并讨论了其与超螺旋 DNA 的相关性。我们表明，由于富含较弱 AT 碱基对的区域中部分扭转释放，活体内持续的 DNA 泡很可能发生。单个 DNA 质粒成像实验清楚地证明了在游离溶液中存在泡。
