盐离子对B-DNA到Z-DNA结构转变影响的理论研究

在已给出的与溶液盐浓度有关的DNA弹性模型基础上, 考虑到Z-DNA的碱基堆积和氢键相互 作用, 给出了一个新的B-DNA到Z-DNA的结构转变模型. 研究了盐浓度对B—Z结构转变特性的影响, 得到了力延伸曲线、折叠角概率分布以及B—Z结构转变的临界扭矩随盐浓度的变化规律.结果表明: 当盐浓度达到2.4mol/L时, 松弛DNA的Z构象开始出现, 并且随盐浓度的增加, Z构象存在的概率增大, B—Z转变所需的扭转力矩减小. 关键词：DNA弹性盐浓度B—Z结构转变堆积能

The theoretical study of the effects of salt on structure transition of B-DNA to Z-DNA

On the basis of our previous elastic model which is related to the salt ion conc entration, we put forth a new model of B-DNA to Z-DNA transition by considerin g interactions of the hydrogen-bond and base-stacking in Z-DNA, and discuss the effects of salt concentration on the structure transition of B-Z and obtain the force extension curves, the probability distribution curve of the folding angle and the critical torque of B-Z transition at various salt concentrations. The results show that Z-DNA appears when salt concentration reaches 2.4mol/L,and the probability of Z-form begins to increase and the torsion of B-Z trans ition decreases with the increase of salt concentration.