2-羟丙基-β环糊精-过氧化苯甲酰包合物与小牛胸腺DNA的相互作用

摘要

在生理酸度条件下(pH 7.4),运用多种光谱分析方法研究了2-羟丙基-β环糊精(Hp-βCD)-过氧化苯甲酰(BPO)包合物与小牛胸腺DNA(ctDNA)的相互作用.结果表明,Hp-βCD与BPO形成1:1的包合物,两者的包合常数为2.40×104 L·mol-1.计算出的热力学参数表明,氢键和范德华力是Hp-βCD-BPO包合物与ctDNA相互作用的主要驱动力.Hp-βCD-BPO包合物存在下,ctDNA的熔点和粘度无明显变化,KI荧光猝灭效应和Na3PO4的存在使Hp-βCD-BPO-ctDNA复合物的荧光强度发生改变,表明Hp-βCD-BPO包合物与ctDNA主要通过沟槽和静电方式结合.红外光谱(FT-IR)和圆二色谱(CD)分析结果显示,Hp-βCD-BPO包合物主要与ctDNA的鸟嘌呤(G碱基)发生特异性结合,并引起ctDNA的B构象向A构象转变.%The interaction between 2-hydroxypropy1-β-cyclodextrin-benzoyl peroxide inclusion compound(Hp-βCD-BPO) and calf thymus DNA(ctDNA) in pH 7.4 Tris-HCl buffer was investigated by multi-spectroscopic techniques.The results showed the 1:1 inclusion compound was formed between BPO and Hp-βCD,with the inclusion constant being determined to be 2.40×104 L·mol-1.The calculated thermodynamic parameter indicated that the binding of Hp-βCD-BPO inclusion compound to ctDNA was driven mainly by hydrogen bonding and van der Waals interaction.It was found that Hp-βCD-BPO bound to ctDNA with groove and electrostatic binding as evidenced by no significant change in melting and viscosity of ctDNA as well as in iodide quenching effect and the fluorescence intensity of Hp-βCD-BPO-ctDNA varied in the presence of Na3PO4.The results from FT-IR and CD analysis manifested that Hp-βCD-BPO was preferentially bounded to the guanine(G) base of ctDNA,and led to a transformation from B?like DNA structure to A-like conformation.