K. Vickery et al., DNA binding of Lambda- and Delta-cis-beta-[Ru(RR-picchxn)(phen)](2+) studied by NMR and flow linear dichroism spectroscopy, J BIO STRUC, 17(3), 1999, pp. 519-525
Two novel substitutionally-inert diastereomeric ruthenium(II) cations of th
e form Lambda- and Delta-cis-beta-[Ru(RR-picchxn)(phen)](2+), where RR-picc
hxn is N,N'-dimethyl-N,N'-di(2-picolyl)-IR,2R-diaminocyclohexane and phen i
s 1,10-phenanthroline, have been studied with respect to their interactions
with duplex DNA. NMR investigations show that both diastereomers bind to t
he oligonucleotide [d(CGCGATCGCG)](2) in the fast exchange regime and that
binding predominantly takes place in the minor groove of the oligonucleotid
e, but that the governing interactions are significantly different for the
two Delta and Lambda forms. Linear dichroism data support the latter interp
retation, in that the relative orientations of cis-beta-[Ru(RR-picchxn)(phe
n)](2+) to calf thymus DNA also are observed to differ for the Delta and La
mbda diastereomers. Interpretation of these data indicates the Lambda form
to be bound with the planar phen ligand closely parallel to the DNA base-pa
irs, but the average orientation of the phen ligand in the Delta form devia
tes significantly from a parallel alignment.