【作者】 赵秋香；

【导师】 杨培慧； 冯德雄；

【作者基本信息】 暨南大学 ， 分析化学， 2004， 硕士

【摘要】 本论文采用电化学方法，研究了谷胱甘肽（GSH）与Cr（Ⅵ）的相互作用，从其循环伏安（CV）和UV-Vis光谱行为可见：在pH5.6的HAC-NaAC缓冲溶液中，当GSH浓度为K₂Cr₂O₇浓度5倍以上时，Cr（Ⅵ）与GSH相互作用，形成一新的Cr（Ⅴ）中间态化合物GSCrO₃^-：于+0.21V和+0.36V（vsSCE）处产生一对新的氧化-还原峰：在UV-Vis光谱上于431nm处产生一新的吸收峰，当有Zn²⁺存在时，该体系的电化学和光谱行为都得到了加强，Zn²⁺对中间化合物的生成和分解过程中起着双重催化作用。本文进一步运用电化学和光谱动力学方法探讨了GSH与Cr（Ⅵ）的作用机制，探讨了中间态化合物GSCrO₃^-的形成和不稳定性，为Cr（Ⅵ）与GSH的作用机制的研究提供新的分析方法。 对Cr（Ⅵ）与GSH配合物诱导DNA变性进行了循环伏安（CV）、光谱以及圆二色谱（CD）表征，并运用原子力显微镜（AFM）对该过程进行了可视化研究。在pH5.6的HAC-NaAC缓冲溶液中，DNA于+0.20V和0V处分别出现一对很弱的氧化还原峰，在258nm处有强的UV特征吸收，其CD谱体现B型特征，DNA的AFM图谱呈现出铺展的链状；当往溶液中加入Cr（Ⅵ）和GSH配合物时，电化学响应峰峰电流增强，258nm处UV特征吸收峰增高，并且从DNA的CD谱可以看出：溶液中加入Cr（Ⅵ）和GSH配合物后DNA的结构从B型转变到A型，从AFM图谱可以明显的看到Cr（Ⅵ）与GSH配合物诱导DNA断链的过程。这为Cr（Ⅵ）的致癌机理的研究提供了新的表征方法。 以溴化乙锭（EB）为荧光探针，采用荧光光谱法探讨了Cr（Ⅵ）和GSH配合物与DNA的作用机制，研究了体系的荧光光谱、荧光动力学、DNA热变性曲线及离子强度、H₂PO₄^-的影响。结果表明：在PH=7.4的Hepes缓冲溶液中，Cr（Ⅵ）与GSH配合物能诱导DNA双螺旋结构发生变化，并进一步推测了其中的反应机理。更多还原

【Abstract】 Interactions between chromium(VI) and GSH were studied by electrochemical and spectral methods. The cyclic voltammetric and spectral behaviours were obtained . When the consentration of GSH is far more than that of Cr(VI) (CcsH:Ccrvi) >5:1), A new pair of redox peaks were observed at +0.2 IV and +0.36V(vsSCE) in acetate buffer solution (pH5.6). The peaks of +0.2 IV and +0.36V were the redox peaks of the intermediates, and corresponded to the new UV-Vis absorption peak at 431nm . When Zn2+ was added to above solution, both the peaks current and the asorbance of the peak at 431nm were enhanced. Therefor Zn2+ acted as a true catalyst for both the formation and decomposition of the observed intermediate. The results indicated that a new intermediates were formed . In this paper, the properties of the peak current and the UV-Vis spectral dynamics were studied in detail. The mechanisms of the electrode reactions were discussed.The damages of DNAinduced by Cr (VI) -GSH complexes were characterized by using electrochemistry, spectra, and AFM imaging. The electrochemical activity of DNA was very weak, no matter the DNA in solution or modified on the surface of electrode. However, the redox peaks of DNA appeared at emerge the potentials of +0.20V and 0V in HAc-NaAc buffer solution (pH5.6), as adding Cr (VI) - GSH complexes to the solution. Moreover, the peaks current increased with the concentration of Cr( VI)- GSH complexes and incubation time increasing . The results showed that the Cr (VI) - GSH complexes resulted in the denaturation of DNA. The heating and SDS denaturations were further used to confirm DNA denaturation induced by the Cr ( VI) - GSH complexes. CD spectra and AFM imaging were used to illustrate the cleavage process of DNA.Using ethidium bromide(EB) as fluorescence probe was applied to investigate the interaction between Cr (VI) -GSH complexes and DNA, In the Hepes solution (pH7.4),The results of several experiments, such as fluorescence spectrum, fluorescence dynamics spectrum, curve of the heating denaturation of DNA and influence of ion intensity and H2P(V , showed that Cr ( VI) -GSH can destroy the2004configuration of DNA, which resulted in the descend of fluorescence indensity of the DNA-EB system.更多还原