茜草色素光泽汀与DNA相互作用机理的研究

A Mechanistic Study on the Interaction between DNA and Lucidin Using Madder Color

在p H 7.41的生理条件下,以溴化乙锭(EB)作为光谱探针,采用紫外可见光谱和荧光光谱等方法对茜草色素光泽汀(Luc)与DNA的相互作用机理做了初步探讨。同时还研究了光泽汀对DNA分子的热变性以及粘度影响。在碘化钾(KI)效应实验中,以碘化钾作为荧光猝灭剂探讨光泽汀与DNA分子之间的相互作用方式。循环伏安法法研究光泽汀在玻碳电极上的电化学规律,根据循环伏安曲线及溴化乙锭对光泽汀与DNA作用的影响,推断光泽汀与DNA主要作用方式为嵌插。结果显示:光泽汀与DNA之间相互作用的结合比为n(Luc):n(DNA)=2:1,Luc-DNA复合物的表观摩尔吸光系数ε=8.12×104 L/(mol·cm)。在光泽汀存在的条件下,DNA分子的热变性温度和粘度都会增加,并且在碘化钾效应实验中可降低碘化钾的荧光猝灭效应,同时Luc的电化学变化规律同EB相似。在本实验条件下,光泽汀与DNA分子之间的相互作用方式存在嵌插。

The mechanism of interaction between lacidin （Lac） and DNA at physiological pH of 7.41） was investigated by ultraviolet-visible spectrum and fluorescence spectroscopy, using ethidium bromide （EB） as a probe, The effect of Luc on thermal denaturation and viscosity of DNA was also evaluated. In addition, the interaction between Luc and DNA was explored in a potassium iodide （KI）-mediated fluorescence quenching experiment. Luc was also subjected to electrochemical characterization on a glass carbon electrode, by cyclic voltammetry. Based on the curve obtained by cyclic voltammetry analysis, and the effect of EB on the interaction between Luc and DNA, the interaction was proposed to be mediated via intercalation. The binding ratio of Luc-DNA was determined to be 2：1, and the apparent molar absorption coefficient （ε） was determined to be 8.12 × 10^4 L/（mol-cm）. The presence of Luc increased the thermal denaturation temperature and viscosity of DNA molecules, attenuated the fluorescence quenching effect of KI, and resulted in the display of similar electrochemical properties as EB. Under the conditions used in the present study, Luc was observed to interact with DNA molecules via intercalation.