Research On The Property Of Electrochemical Probe Eu (Ⅲ)

Centrin is an acidic calcium-binding protein of 19.5KDa, which is a member of CaM protein superfamily existing widely in biological centrosomes. Centrin contains four potential calcium-binding sites of EF-hand structure. Up to the present, research on centrin has focused mainly on its biological function and structure.However, it is difficult to get the structural information of calcium ion coordination environment, because calcium ion, which is important for physiological function, is neither color nor magnetism. Due to optical, electrical and magnetic properties, the rare earth ions often replaced calcium ion for the investigation of coordination environment. Furthermore, the rare earth ions and calcium ion have very similar chemical properties so calcium ions can be easily replaced by rare earth ions to detect calcium distribution micro-environment and bonding structure. After the coordination environment changes, the properties can be detected by experimental means to deduce their behavior in organisms.In this thises, Eu³⁺ was chosen as an electrochemical probe, and some basic research on the interactions between Eu³⁺ and centrin had been done.Firstly, the electrochemical properties of Eu³⁺ had been discussed detailedly. A pair of redox peak of Eu³⁺ of the concentration of 1×10^-4 mol/L appeared on both bare pyrolytic graphite electrode and bare glassy carbon electrode in HAc-NaAc 0.2 mol/L pH 6.0 buffer, and controlled by the diffusion current. There was also a good reversible redox peak of Eu³⁺ of the concentration of 1×10^-3 mol/L on bare pyrolytic graphite electrode in Heps 0.01 mol/L pH7.4 and in the charge of diffusion current. Moreover, the results showed that different electrodes, different concentrations, different buffers and different acidity of the buffers had a significant impact on Eu³⁺ electrochemical properties.Secondly, the interaction of Eu³⁺ and EHPG which is mimic for transferrin had been investigated by cyclic voltammetry. A pair of reversible redox peaks of Eu-EHPG appeared on bare glassy carbon electrode in pH 6.0, 0.2mol/L HAc-NaAc buffer at room perature. Eu³⁺ combined with EHPG in 1/1 in Tris-HCl pH 7.2 buffer.Thirdly, the binding between Eu³⁺ and human serum protein and between Eu³⁺ and bovine serum protein had studied by cyclic voltammetry. And the experimental results will be helpful for the research on the interaction between Eu³⁺ and centrin.Finally, instead of Ca²⁺ of centrin, Eu³⁺ had been done some research on the binding between Eu³⁺ and the different fragments of centrin respectively. The experimental results showed that Eu³⁺ and centrin with different calcium-binding segments interacted in 0.01 mol/L pH7.4 Heps buffer at room temperature. Redox potential changed and the peak current decreased simultaneously.In addition, the paper also studied the interactions between a wide range of compounds with DNA by cyclic voltammetry to judge how the compounds combine with DNA according to their CV curve. All the electrochemical measurements results showed that they are the same with the conclusions of UV and fluorescence spectroscopy.