原儿茶酸与小牛胸腺DNA的沟槽结合

Groove binding between protocatechuic acid and calf thymus DNA

利用荧光光谱法和分子模拟技术,并结合DNA单双链、盐效应、熔点和粘度测量等实验,研究了生理酸度条件下(pH7.4)原儿茶酸与小牛胸腺DNA(ctDNA)的结合性质和结合模式。结果表明,ctDNA能够结合原儿茶酸,并通过静态方式猝灭原儿茶酸的内源荧光,两者的结合常数在103 L·mol^-1数量级,氢键和疏水作用是原儿茶酸与ctDNA结合的主要驱动力。原儿茶酸的加入没有明显改变ctDNA的熔点和粘度,单链ctDNA猝灭原儿茶酸荧光的能力大于双链ctDNA,并且NaCl浓度的增加对原儿茶酸-ctDNA复合物的荧光强度没有明显的影响,表明原儿茶酸与ctDNA主要通过沟槽模式结合。分子模拟显示原儿茶酸的结合位点在ctDNA的小沟区,且与碱基胸腺嘧啶(T)形成氢键。分子模拟结果进一步确证了二者之间的沟槽作用模式。

The binding properties and mode between protocatechuic acid(PCA)and calf thymus DNA(ctDNA)in simulative physiological buffer(pH 7.4)were investigated by fluorescence spectroscopy and molecular simulation technique via single and double stranded DNA experiment,salt effect,melting experiment and viscosity measurement.The results showed that ctDNA could interact with protocatechuic acid and quench the endogenous fluorescence of protocatechuic acid by a static mechanism.The binding constant between PCA and ctDNA was in the order of 103 L·mol^-1.The hydrogen bonds and hydrophobic interactions were the main driving forces.The addition of PCA did not obviously change the melting temperature and viscosity of ctDNA,the fluorescence quenching of PCA by ss ctDNA was stronger than that of ds ctDNA,and increasing the concentration of NaCl did not significantly affect the fluorescence intensity of PCA-ctDNA complex,indicating that the binding between ctDNA and PCA was groove mode.The molecular simulation result further confirmed the groove binding between PCA and ctDNA.