9 research outputs found
Hexakis(1H-imidazole-κN 3)cobalt(III) tris(hexafluoridophosphate) hexahydrate
In the crystal structure of the title compound, [Co(C3H4N2)6](PF6)3·6H2O, the CoIII atom lies on a special position with site-symmetry and the P atom is located on a special position with site symmetry . The CoIII atom has an almost ideal octahedral coordination formed by the N atoms of six imidazole ligands. The water molecules form hydrogen-bonded helical chains propagating in [001] by O—H⋯O interactions with a distance of 2.913 (2) Å. They simultaneously interact as hydrogen-bond acceptors and donors with the cations and anions, respectively, resulting in the formation of a three-dimensional assembly. Weak C—H⋯F interactions further stabilize the crystal structure
Binding studies of metal–salphen and metal–bipyridine complexes towards G‐Quadruplex DNA
The proposed in vivo formation of G-quadruplex
DNA (G4 DNA) in promoter regions of oncogenes and in telomeres
has prompted the development of small molecules
with high affinity and selectivity for these structures. Herein
we report the synthesis of a new di-substituted bipyridine
ligand and the corresponding complexes with Ni2+ and
VO2+. Both these new complexes have been characterized
spectroscopically and by X-ray crystallography. Detailed DNA
binding studies of these two complexes, together with three
previously reported metal salphen complexes, are presented.
Using FRET melting assays, the binding affinity and selectivity
of the five metal complexes against six different G4 DNA
structures as well as a duplex DNA have been determined.
In addition, we present detailed ITC and UV/Vis studies to
characterize the interaction of the complexes with human
telomeric G4 DNA. Finally, we show via a polymerase stop
assay that these complexes are able to stabilize a G4 DNA
structure (from the c-Myc oncogene promoter) and halt the
activity of Taq polymerase.UK’s Engineering and Physical Sciences Research Council
(EPSRC) (grant number: EP/H005285/1
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Interactions between metal ions and DNA
84 years elapsed between the announcements of the periodic table and that of the DNA double helix in 1953, and the two have been combined in many ways since then. In this chapter an outline of the fundamentals of DNA structure leads into a range of examples showing how the natural magnesium and potassium ions found in nature can be substituted in a diversity of applications. The dynamic structures found in nature have been studied in the more controlled but artificial environment of the DNA crystal using examples from sodium to platinum and also in a range of DNA-binding metal complexes. While NMR is an essential technique for studying nucleic acid structure and conformation, most of our knowledge of metal ion binding has come from X-ray crystallography. These days the structures studied, and therefore also the diversity of metal binding, go beyond the double helix to triplexes, hairpin loops, junctions and quadruplexes, and the chapter describes briefly how these pieces fit into the DNA jigsaw. In a final section, the roles of metal cations in the crystallisation of new DNA structures are discussed, along with an introduction to the versatility of the periodic table of absorption edges for nucleic acid structure determination
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The eyes have it: using X-ray crystallography to determine the binding modes of medically relevant ruthenium/DNA complexes
Ruthenium polypyridyl complexes have been intensively studied in many laboratories around the world for their potential applications in chemotherapy, including photodynamic therapy, and as useful DNA probes and sensors in cells. This chapter discusses the ways in which X-ray crystallography can contribute to our understanding of these applications at the molecular level. The design of useful compounds relies on assumptions about the shape and possible flexibility of the molecular target, and an appreciation of how and why a small change in the molecular design can have a major impact on the effectiveness of the compound