A series of luminescent iridium(iii) complexes were synthesised and evaluated for their ability to act as luminescent G-quadruplex-selective probes. The iridium(iii) complex 9 [Ir(pbi)2(5,5-dmbpy)]PF6 (where pbi = 2-phenyl-1H-benzo[d]imidazole; 5,5-dmbpy = 5,5'-dimethyl-2,2'-bipyridine) exhibited high luminescence for G-quadruplex DNA compared to dsDNA and ssDNA, and was employed to construct a...

Oxazole-containing macrocycles represent a promising class of anticancer agents that target G-quadruplex DNA. We report the results of spectroscopic studies aimed at defining the mode, energetics and specificity with which a hexaoxazole-containing macrocycle (HXDV) binds to the intramolecular quadruplex formed by the human telomeric DNA model oligonucleotide d(T2AG3)4 in the presence of potassi...

Due to the long-range nature of high-order interactions between distal components in a biomolecule, transition dynamics of tertiary structures is often too complex to profile using conventional methods. Inspired by the exploded view in mechanical drawing, here, we used laser tweezers to mechanically dissect high-order DNA structures into two constituting G-quadruplexes in the promoter of the hu...

The G-quadruplex, a four-stranded DNA structure with stacked guanine tetrads (G-quartets), has recently been attracting attention because of its critical roles in vitro and in vivo. In particular, the G-quadruplex functions as ligands for metal ions and aptamers for various molecules. Interestingly, the G-quadruplex can show peroxidase-like activity with an anionic porphyrin, iron (III) protopo...

The structural interconversion between the G-quadruplex and duplex in vivo is an important subject. In the present study, we used human telomeric DNA duplex composed of GGG(TTAGGG)(3)/CCC(TAACCC)(3) as a model system to investigate its properties under near physiological conditions by spectroscopic methods. Circular dichroism and fluorescence spectra demonstrated that G-quadruplex structure can...

Conformational changes in DNA G-quadruplex (GQ)-forming regions affect genome function and, thus, compose an interesting research topic. Computer modelling may yield insight into quadruplex folding and rearrangement, particularly molecular dynamics simulations. Here, we show that specific parameters, which are distinct from those commonly used in DNA conformational analyses, must be introduced ...

Following previous studies on anthraquinone and acridine-based G-quadruplex ligands, here we present a study of similar aromatic cores, with the specific aim of increasing G-quadruplex binding and selectivity with respect to duplex DNA. Synthesized compounds include two and three-side chain xanthone and xanthene derivatives, as well as a dimeric "bridged" form. ESI and FRET measurements suggest...

The research on the G-quadruplex DNAs has received much attention in recent years and numerous reports appeared probing its detection, structure, stability, reactivity and selectivity, aimed mainly for the chemical intervention of specific biological activity or sensor applications. Our study has demonstrated the use of a fluorogenic dye, Thioflavin T, to stabilize the telomeric DNA strand into...

The sequence specificity of a duplex and the cation dependent self-assembly of a G-quadruplex were combined to design rationally DNA G-quadruplex arrays connected by duplexes.

A label-free fluorescence K(+) assay was developed using riboflavin, a new G-quadruplex ligand, and a G-quadruplex sequence (PW17).