Electrochemical Studies On Interaction Between ApoCopC,BSA And Cu(Ⅱ),Cu(Ⅰ),Cd(Ⅱ),Ag(Ⅰ)

Copper is an essential micronutrient in all living organisms. However, its excess present is toxic. CopC is a small soluble copper protein which plays an important role in regulating copper homeostasis. The protein is known to confirm two separated binding sites with high affinities for Cu2+ and Cu+, which locate at the two opposite sides of the hydrophobic barrel. The role of CopC in copper trafficking is an open question.In this paper, The interaction of Cu(Ⅱ), Cu(Ⅰ), Cd(Ⅱ), Ag(Ⅰ) with apoCopC and BSA was studied by cyclic voltammetry and electrochemical impedance spectroscopy based on apoCopC and BSA immobilised on gold electrode and glassy carbon electrode.Firstly, An electrode modified with protein monolayer was prepared by the self-assembly of apoCopC at a gold electrode. The interaction of apoCopC with Cu(Ⅱ) had been investigated by cyclic voltammetry at apoCopC-modified gold electrode. The oxidation peak and reduction peak of Cu2+ at apoCopC-modified gold electrode had been found. The peak potential s of Cu2+ at apoCopC-modified electrode shifted evidently comparing with that at the bare gold electrode, indicated that apoCopC could adsorb on the electrode firmly and Cu2+ bound to apoCopC to form a complex. The voltammetric behavior of Cu2+ on the apoCopC/Au electrode was studied by scan rate, accumulation time, various concentration and presence of TNS. The electron transfer coefficient(α) was 0.5, electron transfer rate constant (ks) was 0.75 s-1. The surface concentration of Cu2+-CopC (Γ) was 2.7×10-10 mol·cm-2 which showed it was monolayer modified. The oxidation peak and reduction peak of Cd2+ at apoCopC-modified gold electrode had been found. The peak potentials of Cd2+ at apoCopC-modified electrode shifted evidently comparing with that at the bare gold electrode, indicated that Cd2+ bound to apoCopC to form a complex. The oxidation peak and reduction peak of Cd2+ at apoCopC-modified gold electrode was controlled by diffusion and adsorpti on. The surface concentration of Cd2+-CopC (Γ) was 1.3×10-10 mol·cm-2 which showed it was sub-monolayer modified.Secondly, the glassy carbon electrode modified with apoCopC was prepared and the adsorption of apoCopC on electrode was studied. The electrochemical behavior of Cu(Ⅱ), Cu(Ⅰ), Ag(Ⅰ) on apoCopC-modified electrode was studied. It was found that the reduction peak potential of Cu2+ and the formal potential of Cu2+/Cu+ redox couples shifted negatively, at apoCopC-modified glassy carbon electrode, comparing with that at the bare glassy carbon electrode. These indicated that Cu2+ could bind apoCopC via non-hydrophobic (electrostatic and/or covalent) interaction. The reduction peak potential of Cu(Ⅰ) and the formal potential of Cu+/Cu redox couples shifted negatively comparing with that at the bare glassy carbon electrode, indicated that Cu(Ⅰ) could bind apoCopC via non-hydrophobic (electrostatic and/or covalent) interaction. The reduction peak potential of Ag+ and the formal potential of Ag+/Ag redox couples shifted negatively comparing with that at the bare glassy carbon electrode, indicated that Ag(Ⅰ) could bind apoCopC via non-hydrophobic (electrostatic and/or covalent) interaction.Finally, BSA-modified gold electrode/glassy carbon electrode was prepared. The interaction of Cu(Ⅱ), Cu(Ⅰ), Cd(Ⅱ), Ag(Ⅰ) with BSA was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical behavior of Cu(Ⅱ),Cd(Ⅱ) at BSA-modified gold electrode was studied. Cu(Ⅱ), Cu(Ⅰ), Ag(Ⅰ) could bind BSA via non-hydroph obic (electrostatic and/or covalent) interaction.