DNA interactions with small solutes: change in the character of the binding of [Ru(NH3)5pz]2+ to DNA as a consequence of changes in the solvent

The ionic strength effect on the binding of [Ru(NH3)5pz]2+ to DNA has been studied using a kinetic approach consisting in the study of the kinetics of the oxidation of this ruthenium complex by [Co(C2O4)3]3- (C2O4=oxalate anion) at different ionic strength and in the presence and absence of buffers. When the ionic strength increases, the strength of the binding decreases, as a consequence of the partial neutralization of the charge on the DNA. The increase of the ionic strength also produces a change in the character of the binding, which changes from anti-cooperative to non-cooperative when the ionic strength increases