Tobias I, Olson W K
Department of Chemistry, Rutgers, State University of New Jersey, New Brunswick 08903.
Biopolymers. 1993 Apr;33(4):639-46. doi: 10.1002/bip.360330413.
Elasticity theory of naturally curved rods is employed to study the effects of intrinsic curvature on the properties of the equilibrium conformations of supercoiled DNA. The results stand in sharp contrast to those obtained when the molecule is viewed as being straight in its relaxed form. Starting from very fundamental principles of the theory, we show that the torsion of an open segment with a curved duplex axis can vary when the temperature, and along with it, the intrinsic twist is changed. Conversely, an imposed helicity, such as might be associated with binding to a histone, can change the intrinsic twist. It is also shown that another consequence of the presence of naturally curved sequences is that the twist density will, in general, vary with position along the chain in all equilibrium states. Then portions of the molecule will be more or less susceptible to interaction with other agents sensitive to such a variation. Finally, some closed equilibrium global structures uniquely associated with intrinsic curvature are discussed.
运用自然弯曲杆的弹性理论来研究内在曲率对超螺旋DNA平衡构象性质的影响。这些结果与将分子在其松弛形式下视为直线时所获得的结果形成鲜明对比。从该理论的非常基本的原理出发，我们表明，当温度以及随之而来的内在扭曲发生变化时，具有弯曲双链轴的开放片段的扭转会发生变化。相反，诸如与结合组蛋白相关的施加螺旋度可以改变内在扭曲。还表明，存在自然弯曲序列的另一个结果是，在所有平衡状态下，扭曲密度通常会沿着链随位置而变化。那么分子的某些部分将或多或少容易与对这种变化敏感的其他试剂相互作用。最后，讨论了一些与内在曲率独特相关的封闭平衡全局结构。
