Insights into the potential toxicity of Zn(II) to catalase and their binding mechanisms

Abstract

As a common metal, Zinc was widely used in the in the galvanising industry. However, the overuse had contributed to the environmental overexposure of zinc, which had caused a number of health issues in environmental organisms. Catalase (CAT) plays a critical part in regulating oxidative stress in the body of humans. Interactions between Zn(II) and CAT were examined in this paper using a variety of spectroscopic techniques, molecular docking, isothermal titration calorimetry (ITC) and enzyme activity assay. According to the results, Zn(II) can interact with CAT fluorophore residues like Trp and Tyr and demonstrate fluorescence sensitization to these amino acids. Direct contact between CAT and Zn(II) led to the disruption of protein backbone structure and peptide chain tightening. When exposed to Zn(II), the secondary structure of CAT was altered, including the decreased α-helix of CAT, increased β-sheet content, and the increased grain size of the zinc-CAT complex. Measurement of thermodynamic parameters of the binding reaction by ITC showed that the force between Zn(II) and CAT was electrostatic force. In addition, the binding site of Zn(II) is close to the active center of CAT which boosted enzyme activity. In conclusion, our research demonstrates that Zinc has an impact on both the structure and function of CAT.