大黄素与DNA相互作用方式的研究

摘要

The mode of interaction of emodin and DNA was studied through fluorescence analysis, UV -visible absorption spectra, viscosity measurement and competition experiments with ethidium bromide. When the optimal conditions were set as follows: pH 7.4, ionic strength of 30 mmol/L NaC1, temperature of 37 ℃ and reaction time of 35 min, the fluorescence intensity of emodin was decreased with the increase of DNA concentration. The isosbestic points (380 nm and 475 nm) of emodin was red shifted by 5 nm in the presence of DNA, indicating that the complex of emodin and ctDNA was formed. Meanwhile, the fluorescence spectra of adenine and DNA showed the similar fluorescence quenching to that of DNA, indicating that emodin was embedded in base pairs and the hydrogen bond between adenine and cytosine was damaged.%通过分子荧光分析、紫外可见吸收光谱及粘度分析以及与溴化乙锭的竞争性实验对大黄素与DNA之问的作用模式进行了考察.在pH 7.4,低离子强度(30 mmol/L NaCl)及恒温37℃条件下反应35 min,大黄素的荧光强度随DNA加入浓度的增加而递减,紫外可见吸收光谱在380、475 nm处出现等吸收点并红移5nm,表明大黄素与ctDNA形成了复合物,两者之问的作用模式为嵌入式.同时,腺嘌呤与大黄素相互作用的荧光光谱呈现出与DNA相似的荧光猝灭现象,表明大黄素已嵌入碱基对之间,破坏了腺嘌呤与胞嘧啶的氢键结合.