Dna Interaction With Chiral Metal-Complexes

Despite extensive study of DNA interaction with propeller-shaped metal complexes, such as the DELTA and LAMBDA enantiomers of [Ru(1,10-phenanthroline)3]2+, the basis for their enantioselectivity, and even their binding modes, are not yet fully understood. H-1 NMR studies of the interactions with the self-complementary oligonucleotide d(CGCGATCGCG)2 indicate that both enantiomers bind into the minor groove of the central AT-TA region, but with a rapid exchange between the bound and free states. Flow linear dichroism (FLD) and circular dichroism (CD) show different binding geometries for the two enantiomers. These two geometries are found in natural DNA as well as in a number of different B form polynucleotides, virtually independent of base composition and of methylation. The DNA interaction with the [Ru(1,10-phenanthroline)3]2+ complexes will be reconsidered in the light of NMR, FLD, CD and fluorescence results.