【摘要】 利用喇曼光谱技术研究了不同摩尔浓度的Zn2+对DNA结构稳定性的影响.结果表明,当Zn2+/PO2- ≤2.0时,Zn2+与DNA磷酸基团上的氧原子结合,形成-PO2-…Zn2+…N7(G)螯合物,这种螯合作用增强了GC 碱基对之间的氢键能量,使得GC碱基对更加稳定;此外,在低浓度情况下,Zn2+还会与腺嘌呤A上的N3结合, 而与A上N3的结合只对AT碱基对有轻微的扰动.当Zn2+/PO2->2.0时,大量的Zn2+开始与胞嘧啶C上的 N3-O2螯合以及与DNA中A上的N1结合,Zn2+与C上的N3-O2的螯合,打断了GC碱基对之间的氢键;与A 上的N1结合时,AT碱基对之间的氢键也被打断.因此,低浓度的Zn2+对DNA的构像起着稳定性作用,但是高浓 度的Zn2+则破坏了DNA构象的稳定性.在高浓度的Zn2+ DNA溶液中,GC受损比AT更为严重,部分C甚至经 过脱氨基现象转化成了T,碱基配对被解开,DNA结构变得不稳定,其主链的几何形状和次级结构发生变化,不 再是一个典型的B型DNA,而是一个修饰过的B′型DNA.更多还原

【Abstract】 Raman spectroscopic technique has been used to study the effect of Zn 2+on the stability of calf thymus DNA macromolecule at different Zn 2+/PO 2 - ratios in solution. The experimental results show that when Zn 2+/PO 2 -≤2.0, Zn 2+ will be bound to the chelate position of guanine(G) at N7 sites and -PO 2 -…Zn 2+… N7(G) chelates will be formed. The chelation strengthens the energy of the H-bond between GC pairs. Simultaneously, Zn 2+ will be also bound to adenine (A) at N3 sites and this binding causes a slight destabilization of the AT pairs. When Zn 2+/PO 2>2.0, a number of Zn 2+ will be bound to Cytosine at N3-O2 sites and disrupt the H-bonds between GC pairs. At the same time, Zn 2+ will be bound to A at N1 sites and disrupt the AT hydrogen bonds. So it can be concluded that at low concentrations, Zn 2+ can stabilize the double strand structure of DNA, whereas at higher concentrations unwinding of the double strand is facilitated. At higher concentrations, the damage of GC pairs is larger than that of AT, even some C is displaced by T by missing an amidogen, base pairs become unpaired, and the geometry and second structure of DNA have changed and it is not a normal B-DNA but a modified B′-DNA.更多还原