A comparative study of DNA complexation with Mg(II) and Ca(II) in aqueous solution: Major and minor grooves bindings
A comparative study of DNA complexation with Mg(II) and Ca(II) in aqueous solution: Major and minor grooves bindings
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DOI：
10.1016/s0006-3495(03)75050-4
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发表时间：
2003-04-01
影响因子：
3.4
通讯作者：
Tajmir-Riahi, HA
中科院分区：
文献类型：
--
作者：
Ahmad, R;Arakawa, H;Tajmir-Riahi, HA
虽然镁-DNA和钙-DNA络合物在固体状态下的结构差异是存在的，但这种在水溶液中的比较研究还很少。本研究的目的是在恒定浓度的DNA(1.25或12.5 mM)和不同浓度的金属离子(2微米-650微米)下，在生理pH的水溶液中研究镁和钙离子与小牛胸腺DNA的结合。采用毛细管电泳法、紫外-可见光谱和傅里叶变换红外光谱等方法测定了水溶液中的阳离子结合模式、结合常数和DNA结构变化。在1222 cm(-1)，K=4.80×10(5)M-1处，主链PO2的不对称伸缩发生了主要的光谱变化(位移和分裂)，而在1222 cm(-1)处，由于没有磷酸盐带的移动和分裂，发生了间接的镁-磷酸盐相互作用，K=5.6×10(4)M-1。金属基键对K=3.20×10(5)M-1的镁离子是直接键合，对K=3.0×10(4)M-1的阳离子是间接键合。观察到主要和次要的沟槽结合，没有改变B-DNA的构象。
Although structural differences for the Mg-DNA and Ca-DNA complexes are provided in the solid state, such comparative study in aqueous solution has been less investigated. The aim of this study was to examine the bindings of Mg and Ca cations with calf thymus DNA in aqueous solution at physiological pH, using constant concentration of DNA (1.25 or 12.5 mM) and various concentrations of metal ions (2 muM-650 muM). Capillary electrophoresis, UV-visible, and Fourier transform infrared spectroscopic methods were used to determine the cation-binding modes, the binding constants, and DNA structural variations in aqueous solution. Direct Ca-PO2 binding was evident by major spectral changes (shifting and splitting) of the backbone PO2 asymmetric stretching at 1222 cm(-1) with K = 4.80 x 10(5) M-1, whereas an indirect Mg-phosphate interaction occurred (due to the lack of shifting and splitting of the phosphate band at 1222 cm(-1)) with K = 5.6 x 10(4) M-1. The metal-base bindings were directly for the Mg with K = 3.20 x 10(5) M-1 and indirectly for the Ca cation with K = 3.0 x 10(4) M-1. Both major and minor groove bindings were observed with no alteration of the B-DNA conformation.