Study on the Binding Mode of a Co(II) Complex with DNA

The mode of binding of CoLCl 2 , here L=bis(2‐benzimidazolylmethyl)amine, with calf thymus DNA has been investigated by fluorescence measurements, equilibrium dialysis, viscosity experiments and gel electrophoresis. The complex was found to bind but weakly to DNA, with binding constant of 1.96×10 4 L/mol determind at 20 °C in a solution containing 5 mmol/L Tris‐HCl (pH 7.1) and 50 mmol/L NaCl. Polyelectrolyte theory was applied to analyse these values. Viscosity experiments show that binding did not alter the relative viscosity of DNA with any complexes to an appreciable extent. Electrophoresis test displayed that the compound could not cleave the DNA. These results show that the complex is essentially electrostatically bound to DNA.