Abstract —Conformational mobility is one of the most important properties of the DNA molecule. A striking example of this mobility is provided by the formation of regions where the double helix is locally unwound. The resulting so-called open DNA states play an important role in transcription, replication, and denaturation. In a “nonrelativistic” approximation, the open DNA states are often modeled as quasiparticles, or kinks, with a certain mass ( m k ), velocity ( u k ), and rest energy ( E 0 k ). When more than one open state forms in a DNA molecule, statistics can be considered for an ensemble of N DNA kinks. The statistical properties of the ensemble are still poorly understood. In this paper the properties were investigated on the basis of recent data on the dynamic characteristics of DNA kinks. It was assumed that the interaction between the kinks is weak, all kinks are identical and the number N of DNA kinks is fixed. The statistical sum Z k , the free energy F k , the velocity distribution function ρ 1 ( v k ), the average energy ε k , the heat capacity C v, k , and the entropy S k were calculated for the ensemble of N DNA kinks. Temperature dependence curves of these characteristics were obtained and compared for four homogeneous sequences (poly(A), poly(T), poly(G), and poly(C)) and the pBR322 plasmid sequence.

中文翻译：

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DNA扭结的动态和统计特性

摘要：构象迁移率是 DNA 分子最重要的特性之一。这种流动性的一个显着例子是双螺旋局部展开的区域的形成。由此产生的所谓开放 DNA 状态在转录、复制和变性中起着重要作用。在“非相对论”近似中，开放的 DNA 状态通常被建模为准粒子或扭结，具有特定的质量 ( mk )、速度 ( uk ) 和静止能量 ( E 0 k )。当一个 DNA 分子中形成多个开放状态时，可以考虑对 N 个 DNA 扭结的集合进行统计。集合的统计特性仍然知之甚少。在本文中，基于 DNA 扭结动态特性的最新数据研究了这些特性。假设扭结之间的相互作用很弱，所有扭结都是相同的，并且 DNA 扭结的数量 N 是固定的。计算了 N 个 DNA 扭结的集合的统计和 Z k 、自由能 F k 、速度分布函数 ρ 1 ( vk )、平均能量 ε k 、热容 C v, k 和熵 S k . 获得了这些特征的温度依赖性曲线，并比较了四种同源序列（poly(A)、poly(T)、poly(G) 和 poly(C)）和 pBR322 质粒序列。