Shahabadi Nahid, Kashanian Soheila, Darabi Farivash
Department of Chemistry, Faculty of Science, Razi University, Kermanshah, Iran.
DNA Cell Biol. 2009 Nov;28(11):589-96. doi: 10.1089/dna.2009.0881.
The present study investigates the binding interaction between a water-soluble Schiff base, N,N'-bis{5-[(triphenylphosphonium chloride)-methyl]salicylidine}-o-phenylenediamine (SF), and calf thymus DNA (CT-DNA) using emission, absorption, circular dichroism, and viscosity studies. In fluorimetric studies, the dynamic enhancement constant (K(D)) and bimolecular enhancement constant (K(B)) were calculated at different temperatures and demonstrated that fluorescence enhancement is not initiated by a dynamic process, but instead by a static process that involves complex DNA formation in the ground state. Further, the enthalpy and entropy of the reaction between SF and CT-DNA showed that the reaction is exothermic and enthalpy-favored (DeltaH = -153.51 kJ mol(-1); DeltaS = -427.67 J mol(-1) K). In addition, detectable changes in the circular dichroism spectrum of CT-DNA in the presence of SF indicated deep conformational changes in the DNA double helix following interaction with SF. Further, the Schiff base at different concentrations is able to perform cleavage of pUC18 plasmid DNA. All these results prove that SF interacts with CT-DNA via an intercalative mode of binding.
本研究通过发射光谱、吸收光谱、圆二色光谱和粘度研究，探究了水溶性席夫碱N,N'-双{5-[(三苯基氯化膦)-甲基]水杨醛}-邻苯二胺（SF）与小牛胸腺DNA（CT-DNA）之间的结合相互作用。在荧光研究中，计算了不同温度下的动态增强常数（K(D)）和双分子增强常数（K(B)），结果表明荧光增强并非由动态过程引发，而是由一个涉及基态下形成DNA复合物的静态过程所致。此外，SF与CT-DNA反应的焓和熵表明该反应是放热且焓有利的（ΔH = -153.51 kJ mol(-1)；ΔS = -427.67 J mol(-1) K）。另外，在SF存在下CT-DNA圆二色光谱的可检测变化表明，与SF相互作用后DNA双螺旋发生了深度构象变化。此外，不同浓度的席夫碱能够切割pUC18质粒DNA。所有这些结果证明SF通过插入结合模式与CT-DNA相互作用。
