虫草素与DNA作用的光谱研究

Study on the Interaction of Cordycepin and DNA

利用紫外光谱及以溴化乙锭 (EthidiumBromide ,EB)为荧光探针 ,研究了虫草素与小牛胸腺DNA的作用机理。讨论了不同浓度虫草素与DNA作用的紫外光谱 ,荧光光谱及磷酸盐对荧光的猝灭作用。从紫外光谱图上可看出DNA发生了明显的增减色效应并有轻微的红移现象 ,说明虫草素可能以其腺嘌呤碱基嵌入到DNA双螺旋碱基对间。DNA的荧光光谱先是增强然后减弱 ,最终伴随轻微的蓝移进一步表明了虫草素可能插入DNA双螺旋碱基对间。同时磷酸盐的猝灭作用说明虫草素与DNA的磷酸集团也能发生作用。最后通过Scatchard方程作图证明 :虫草素与DNA可能存在两种作用方式即插入方式和与DNA的磷酸基团结合。

The absorbance, fluorescence and Scatchard plots methods as well as the effect of phosphate group on the fluorescence intensity of the cordycepin-DNA-EB system were used to study the interaction of the antitumor compound cordycepin and DNA. It is obvious tiat there is hyperchromic effect and hypochromic effect with slight red shift on the subtracted UV spectrum. It proves that the adenine base of cordycepin can be inserted into the double-helix of DNA. The results of the fluorescence intensity that decreases after increases with a little blue shift on the fluorescence spectrum also proved this. At the same time the phosphate can affect the cordycepin-DNA-EB system. Finally that the result depended on the Scatchard equation indicates that cordycepin reacts electrostatically on phosphate backbone of DNA. There also exists an intercalation into the double-helix of DNA.