The Characterization Of The Damages Of DNA Induced By Chromium (Ⅵ)-Glutathione Complexes Through Electroanalytical Chemistry And Spectrometry

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.