Binding Mode between Trp-Dy(III) Complex and Herring Sperm DNA

By means of UV and fluorescence spectra, the binding ratios between Dy(III)(Trp)(3) and DNA. in physiological pH environment(pH7.40) were determined as n(Dy(III)(Trp)),:n(DNA) = 2:1 and n(Dy(III)):n(Trp)=1:3. The binding constant of K-25 degrees C= 5.75 x 10(7) L.mol(-1) and K-37 degrees C=3.27 x 10(5) L.mol(-1) were obtained by double reciprocal method. Thermodynamic function computation demonstrates that Delta S-r(m)circle minus and Delta H-r(m)circle minus are the primary driving power of the interaction between Dy(III)(Trp)(3) and DNA. By combination analysis of the Scatchard and viscometry methods, we suggested that the interaction mode between Dy(III)(Trp)(3) complex and herring sperm DNA be electrostatic and intercalation bindings