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.
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