Interaction of calf-thymus DNA with trivalent La, Eu, and Tb ions. Metal ion binding, DNA condensation and structural features.
Interaction of calf-thymus DNA with trivalent La, Eu, and Tb ions. Metal ion binding, DNA condensation and structural features.
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DOI：
10.1080/07391102.1993.10508680
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发表时间：
1993-04
影响因子：
4.4
通讯作者：
H. Tajmir-Riahi;R. Ahmad;M. Naoui
中科院分区：
文献类型：
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作者：
H. Tajmir-Riahi;R. Ahmad;M. Naoui
在pH 6.5的水溶液中，用金属/DNA(P)的摩尔比(r) 1/80、1/40、1/20、1/10、1/4和1/2研究了小牛胸腺DNA与La3+、Eu3+和Tb3+的相互作用。FTIR光谱变化与DNA结构性质之间的相关性已经建立。在低金属/DNA(P) (r) 1/80时，金属离子主要结合到主链的PO2-基团上，从而增加了碱基堆叠相互作用和双相稳定性。在(r) 1/40和1/20处，金属离子与PO2-和鸟嘌呤N-7位点的结合（螯合）以A-T碱基对的轻微扰动为主。证据来自1712 cm-1波段（T，G）向较低频率的位移和1222 cm-1的PO2-反对称波段向较高频率的位移。在较高的金属/DNA(P)比r > 1/20时，DNA开始凝聚，并发生剧烈的结构变化，同时伴有G-C和A-T几个吸收带的位移和强度变化。尽管观察到一些局部结构修饰，但在DNA凝聚前后没有观察到B-DNA构象的重大偏离。与Cu-DNA复合物（变性DNA）的比较表明，在镧系离子存在下，生物聚合物具有一定程度的螺旋不稳定性。
The interaction of calf-thymus DNA with La3+, Eu3+ and Tb3+ has been investigated in aqueous solution at pH 6.5, using metal/DNA(P) molar ratios(r) 1/80, 1/40, 1/20, 1/10, 1/4 and 1/2. Correlations between FTIR spectral changes and DNA structural properties have been established. At low metal/DNA(P) (r) 1/80, the metal ions bind mainly to the PO2- groups of the backbone, resulting in increased base-stacking interaction and duplex stability. At (r) 1/40 and 1/20, metal ion binding to the PO2- and the guanine N-7 site (chelation) predominates with minor perturbations of the A-T base pairs. Evidence for this comes from the displacement of the band at 1712 cm-1 (T,G) towards a lower frequency and the PO2- antisymmetric band at 1222 cm-1 towards a higher frequency. At higher metal/DNA(P) ratio, r > 1/20, DNA begins to condensate and drastic structural changes occur, which are accompanied by the shift and intensity changes of several G-C and A-T absorption bands. No major departure from B-DNA conformation was observed before and after DNA condensation even though some local structural modifications were observed. A comparison with the Cu-DNA complexes (denaturated DNA) shows some degree of helical destabilization of the biopolymer in the presence of lanthanide ions.