Quantitative parameters for a two-state cooperative transition in duplex DNAs were finally obtained during the last 5 years. After a brief discussion of observations pertaining to the existence of the two-state equilibrium per se, the lengths, torsion, and bending elastic constants of the two states involved and the cooperativity parameter of the model are simply stated. Experimental tests of model predictions for the responses of DNA to small applied stretching, twisting, and bending stresses, and changes in temperature, ionic conditions, and sequence are described. The mechanism and significance of the large cooperativity, which enables significant DNA responses to such small perturbations, are also noted. The capacity of the model to resolve a number of long-standing and sometimes interconnected puzzles in the extant literature, including the origin of the broad pre-melting transition studied by numerous workers in the 1960s and 1970s, is demonstrated. Under certain conditions, the model predicts significant long-range attractive or repulsive interactions between hypothetical proteins with strong preferences for one or the other state that are bound to well-separated sites on the same DNA. A scenario is proposed for the activation of the ilvPG promoter on a supercoiled DNA by integration host factor.

中文翻译：

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DNA 中合作两态平衡的定量模型：实验测试、见解和预测

在过去的 5 年中，终于获得了双链 DNA 中两态协同转变的定量参数。在简要讨论了与两国平衡的存在有关的观察之后本身，简述了所涉及的两种状态的长度、扭转和弯曲弹性常数以及模型的协同参数。描述了模型预测 DNA 对施加的小拉伸、扭曲和弯曲应力以及温度、离子条件和序列变化的响应的实验测试。还指出了大协同性的机制和意义，它使 DNA 能够对如此小的扰动做出显着的反应。证明了该模型解决现存文献中许多长期存在且有时相互关联的难题的能力，包括 1960 年代和 1970 年代众多工人研究的广泛预熔化转变的起源。在一定条件下，该模型预测了假设蛋白质之间存在显着的远程吸引或排斥相互作用，这些蛋白质对与同一 DNA 上分离良好的位点结合的一种或另一种状态具有强烈的偏好。提出了激活 ilvP 的方案G通过整合宿主因子在超螺旋 DNA 上启动子。