Comparative Analysis of [Au(en)2]3+ and [Pt(en)2]2+ non Covalent Binding to Calf Thymus DNA

Abstract

Reactions of the complexes bisethylendiammine gold(III) and bisethylendiammine platinum(II) with calfthymus DNA were comparatively analysed. Both complexes bind DNA non-covalently most probably on the basis of electrostatic interactions. Binding of either complex at low ratios results into modest modifications of B-type DNA conformations, as detected by CD. Far larger CD alterations are observed at high ratios. The gold(III) chromophore is scarcely perturbed by DNA addition Binding of [Au(en)₂]Cl₃ to calf thymus DNA is reversed by sodium cyanide. By analogy with the case of [Pt(en)₂]Cl₂ it is suggested that Auen acts as a minor groove binder.