Enhancement Effect of Zn-Arsenazo III Complex for G-quadruplex DNA Stability of Proto-oncogene Promoter Telomeres

Background: Controlling the structure of proto-oncogene telomeres is very important in antitumor therapy. There are relationships between G-quadruplex DNA and the growth of tumor cell. Methods: In this study, spectroscopic, cyclic voltammetry and viscosity methods were employed to investigate the interaction between Zn-Arsenazo III complex and G-quadruplex DNA by using 4S Green Plus Nucleic Acid Stain as a spectral probe in PBS buffer. The binding ratios were n Arsenazo III : n Zn(II) = 5:1 for Zn-Arsenazo III complex and n Zn- Arsenazo III : n G-quadruplex DNA = 8:1 for Zn-Arsenazo III-G-quadruplex DNA. The bonding constants (Kθ 298.15K=4.44x10⁵ L·mol^-1, Kθ308.15K= 1.00x10⁵ L·mol^-1, Kθ318.15K= 1.04x10⁶ L·mol^-1) were obtained by double reciprocal method at different temperatures, Which was found that the interaction between Zn-Arsenazo III complex and Gquadruplex DNA was driven by enthalpy. Furthermore, the research further confirmed that the interaction mode between Zn-Arsenazo III complex and G-quadruplex DNA was a mixed binding which involved intercalation and non-intercalation interaction. Results and Conclusion: Together these findings also have corroborated the application of stabilizing ligands and intervening with their function for target G-quadruplexes in a cellular context.