Structural highlights
Publication Abstract from PubMedWe report DNA binding studies of the dinuclear ruthenium ligand [{Ru(phen)2}2tppz]4+ in enantiomerically pure forms. As expected from previous studies of related complexes, both isomers bind with similar affinity to B-DNA and have enhanced luminescence. However, when tested against the G-quadruplex from human telomeres (which we show to form an antiparallel basket structure with a diagonal loop across one end), the LambdaLambda isomer binds approximately 40 times more tightly than the DeltaDelta, with a stronger luminescence. NMR studies show that the complex binds at both ends of the quadruplex. Modeling studies, based on experimentally derived restraints obtained for the closely related [{Ru(bipy)2}2tppz]4+, show that the LambdaLambda isomer fits neatly under the diagonal loop, whereas the DeltaDelta isomer is unable to bind here, and binds at the lateral loop end. Molecular dynamics simulations show that the DeltaDelta isomer is prevented from binding under the diagonal loop by the rigidity of the loop. We thus present a novel enantioselective ligand for antiparallel basket G-quadruplexes, with features that make it a useful tool for quadruplex studies. Structural studies on dinuclear ruthenium(II) complexes that bind diastereoselectively to an anti-parallel folded human telomere sequence.,Wilson T, Costa PJ, Felix V, Williamson MP, Thomas JA J Med Chem. 2013 Oct 2. PMID:24088028[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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