NMR evidence for major groove binding of both Λ- and Δ-[Ru(bpy)2(pqx)](PF6)2 to the oligonucleotide d(CGCGAATTCGCG)2

Abstract

The enantiomeric complexes Λ- and Δ-[Ru(bpy) 2(pqx)](PF6)2 [pqx = 2-(2′-pyridyl) quinoxaline] were synthesized and characterized by various spectroscopic techniques. Their binding properties to the oligonucleotide duplex d(CGCGAATTCGCG)2 were subsequently studied by NMR spectroscopy, 1D and 2D NMR techniques provided evidence for major-groove binding of both enantiomers with the oligonucleotide, The Δ-[Ru(bpy)2(pqx)] (PF6)2 enantiomer binds more deeply enantiomer to the oligonucleotide than the Aone. The quinoxalinic moiety of the pqx ligand faces the major groove in the A complex and is oriented at the external side of the adduct in the A complex. Both complexes show some affinity for the T8C9 base sequence of the dodecanucleotide helix. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.