摘要
在pH7.2 Tris缓冲溶液中,采用紫外、DNA熔点、荧光、粘度等手段研究了染料木素铬(Ⅲ)配合物与小牛胸腺DNA(ctDNA)的作用机制,探讨了其作用模式。当加入一定量的ctDNA时,染料木素铬(Ⅲ)配合物的紫外吸收光谱的最大吸收峰产生明显的减色效应;而配合物体系的荧光强度、共振光散射信号随ctDNA的加入逐渐增强。配合物的存在能有效猝灭EB-DNA体系的荧光,且猝灭方式为静态猝灭。同时ctDNA的熔点和ctDNA溶液的粘度随配合物的加入而增大。据此推断,染料木素铬(Ⅲ)配合物与ctDNA之间具有较强的作用,配合物主要以插入方式与DNA结合,二者的键合常数为1.9×105L·mol-1。该研究结果提示染料木素铬(Ⅲ)配合物有望作为抗癌活性候选药物,值得进一步深入研究。
The interaction of the Cr（Ⅲ） complex of genistein （GEN-Cr） with calf thymus DNA （ctDNA） in Tris （pH 7. 2） buffer was investigated using UV spectra, DNA melting, fluorescence spectra and viscosity. From the absorption titration experiment, no obvious red shift was found, but the notable hypochromicities were observed. When cDNA/cGEN-Cr = 3, the π→π^＊ transitions of the complex at 272 nm showed a decrease in intensity of 29. 10%, which indicated that there was remarkable intercalation between complex and DNA base pairs, involving a strong π-stacking interacting between them. The binding constant for the complex was K=1.9× 10^5 mol · L^-1. From the melting curves of ctDNA in the absence and presence of the complex, the melting temperature of ctDNA was found to increase by 5. 5 ℃ from 74 to 79. 5℃ , owing to the increased stability of the helix in the presence of the complex that was intercalated into the double helix. The complex could emit weak luminescence in Tris buffer. The emission intensity of the complex at 340 nm increased steadily with the addition of ctDNA. The result suggested that the complex got into a hydrophobic environment inside the DNA and avoided the effect of solvent water molecules. The strong interaction of the complex and ctDNA also resulted in greatly enhanced intensity of the resonance light scattering spectra. The emission intensity of DNA-EB system at 600 nm decreased remarkably with increasing the complex concentration, which indicated that the complex could be intercalated into DNA and replace EB from the DNA-EB system. According to the classical Sterrr Volmer equation, the quenching plots at 25 and 37℃ both appeared approximately linear. These results showed that there was one predominant quenching style in this process. Viscosity experiments were carried out by an Ubbelodhe viscometer at 20. 0（± 0.1）℃. The relative viscosity of ctDNA increased steadily with the increas in the complex. The result clearly showed that the complex could be intercalated between DNA base pairs, causing an extension of the helix, and thus increased the viscosity of DNA. The results above indicated that there is a relatively strong interaction between the GEN-Cr complex and ctDNA, and the complex could bind ctDNA mainly by intercalation. The research suggested that the GEN-Cr complex may be a promising candidate for anticancer, which deserves further research.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2008年第7期1587-1591,共5页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金项目(20562008)资助
