两种卤代荧光素与DNA作用荧光特性的研究

对四溴荧光素(TBF)、四氯四溴荧光素(TTF)两种卤代荧光素与DNA作用的荧光特性进行了研究，结果表明：TBF和TTF的最大λ_ex/λ_em为518/540 nm和540/560 nm，DNA的存在会使TBF和TTF的荧光强度发生变化;荧光猝灭实验和偏振实验表明：TBF与DNA的作用方式可能是沟槽键合和嵌插作用，而TTF 嵌插在了DNA碱基对之间;盐效应实验表明：溶液离子强度的大小会影响TBF和TTF与DNA的作用;荧光法测得TBF和TTF与DNA的结合常数为1×106和2×106 L·mol-1,结合位点数为0.62和0.16。

Study on the Fluorescence Characteristics of the Interaction between DNA and Two Halogenated Fluoresceins

The fluorescence characteristics of the interaction between DNA and two halogen fluoresceins, tetrabromofluorescein (TBF) and tetrachlorotetrabromofluorescein (TTF), were studied. The result showed that for TBF, lamda ex/ lamda em were 518 nm/540 nm, and for TTF, they were 540 nm/560 nm. The intensity of fluorescence of TBF and TTF changed in the presence of DNA. The fluorescence quenching studies indicated that TBF binds to DNA in the groove and the polarization experiments showed that TBF is intercalated into the DNA base pairs. So the comprehensive interaction mode of TBF with DNA may be that TTF is intercalated into DNA base pairs and binds to DNA in the groove. Both the fluorescence quenching studies and the polarization experiments indicated that TTF is intercalated into the DNA base pairs. It was also found that ionic strength could affect the interaction of TBF/TTF and DNA. The binding constants K are 1 x 10(6) L x mol(-1) and 2 x 10(6) L x mol(-1), and the binding site numbers n are 0.62 and 0.16 for TBF and TTF, respectively.