稀土离子对DNA作用的循环伏安法和光谱法研究

Abstract

运用循环伏安法，紫外光谱和拉曼光谱等方法研究了Ｅｕ３＋、Ｃｅ３＋、Ｅｒ３＋、Ｓｍ３＋、Ｔｂ３＋、Ｌａ３＋、Ｎｄ３＋等稀土金属离子与ＤＮＡ（小牛胸腺）的相互作用．Ｃｅ３＋与ＤＮＡ作用后，Ｃｅ３＋的ＣＶ曲线的峰电流密度明显降低，且氧化峰降低的程度大于还原峰；Ｃｅ３＋的差示ＵＶ曲线呈减色效应，且在２７２ｎｍ处出现新峰；ＤＮＡ的差示ＵＶ曲线呈增色效应；ＤＮＡ的拉曼谱线中８１４ｃｍ－１处的峰消失，表明铈离子对ＤＮＡ的磷酸二酯键具有切断作用．Ｅｕ３＋和ＤＮＡ作用后，Ｅｕ３＋的ＣＶ曲线的峰电流密度仅略有减少，氧化峰和还原峰电流密度降低程度相近，且ＤＮＡ的差示ＵＶ曲线呈减色效应．可能是Ｅｕ３＋和ＤＮＡ磷酸基之间的静电作用使碱基面进一步堆积所致．Ｅｒ３＋、Ｓｍ３＋、Ｔｂ３＋、Ｌａ３＋、Ｎｄ３＋也都能与ＤＮＡ发生作用，但是，与ＤＮＡ作用的能力不同．其中Ｃｅ３＋离子对ＤＮＡ作用最强，且对ＤＮＡ主链磷酸二酯键具有切断功能，Ｃｅ３＋离子有可能成为催化水解切断ＤＮＡ的“分子剪刀”

The interaction between rare earth ions(e.g.Eu 3+ ,Ce 3+ ,Er 3+ ,Sm 3+ ,Tb 3+ ,La 3+ and Nd 3+ ) and DNA had been investigated by using Cyclic Voltammetry, Ultraviolet and Raman Spectroscopy. After the adding of Ce 3+ ion to DNA solution, the cathodic peak current of Ce 3+ ion reduction was found to decrease obviously, and the anodic peak current to decrease even more significantly. Differential UV spectra of Ce 3+ ion depicted hyperchromic effect after the reaction of these two species and a new peak of 272 nm was found. Differential UV spectra of DNA also showed the hyperchromic effect. The peak of 814 cm -1 disappeared in the Raman spectra of DNA. All of above results may be interpreted as the cleavage effect of cerium ion on DNA. Similar effect were observed between Eu 3+ ion and DNA, but less significant than those observed in Ce 3+ -DNA system. Probably due to the electrostatic interaction between Eu 3+ and DNA and the stack effect of the base in DNA. Peak current decreasing and hyperchromic effect were also observed in cases of reaction of DNA with Er 3+ ,Sm 3+ ,Tb 3+ ,La 3+ and Nd 3+ , but all weaker than in Ce 3+ -DNA system. The cleavage effect of Ce 3+ on the phosphodiest linkage in DNA may be useful in employing the Ce 3+ ion as the “Molecular scission” for catalytically hydrolytic cleavage of DNA.