The DNA G-quadruplex-binding porphyrin TMPyP4·Cu was found to form efficient hybrid catalysts for DNA-based asymmetric catalysis when bound to DNA G-quadruplexes. Nucleobase substitution experiments using human telomere-derived G-quadruplex sequences suggest binding of the porphyrin on the 3'-face.

G-quadruplex unfolding within a sequence of two quadruplex units was characterized by gel electrophoresis, calorimetry and spectroscopy. The obtained results suggest that the kinetics and thermodynamics of the individual quadruplex unfolding are affected by its interaction with other DNA secondary structural elements.

Human telomeric RNA has been identified as a key component of the telomere machinery. Recently, the growing evidence suggests that the telomeric RNA forms G-quadruplex structures to play an important role in telomere protection and regulation. In the present studies, we developed a 19F NMR spectroscopy method to investigate the telomeric RNA G-quadruplex structures in vitro and in living cells....

Because various non-parallel G-quadruplexes of human telomeric sequences in K+ solution can be converted to a parallel G-quadruplex by adding polyethylene glycol (PEG) as a co-solvent, we have taken advantage of this property of PEG to study the covalent attachment of a PEG unit to a G-quadruplex ligand, 3,6-bis(1-methyl-4-vinylpyridinium) carbazole diiodide (BMVC). The hybrid ligand with the P...

Six novel di-substituted phenanthroline derivatives 5a-7a and 3b-5b have been prepared, and their binding interactions with human telomeric (h-telo) and promoter (c-kit2 and c-myc) G-quadruplex DNAs were investigated. All the compounds are potent stabilisers of the G-quadruplex structures and compounds 3b, 4b, and 5b exhibit high G-quadruplex DNA selectivity over duplex DNA. The binding affinit...

Human telomeric DNA consists of tandem repeats of the sequence d(TTAGGG). The formation and stabilization of DNA G-quadruplexes in the human telomeric sequence have been shown to inhibit the activity of telomerase, thus the telomeric DNA G-quadruplex has been considered as an attractive target for cancer therapeutic intervention. However, knowledge of the intact human telomeric G-quadruplex str...

Four-stranded nucleic acid structures called G-quadruplexes have been associated with important cellular processes, which should require G-quadruplex-protein interaction. However, the structural basis for specific G-quadruplex recognition by proteins has not been understood. The DEAH (Asp-Glu-Ala-His) box RNA helicase associated with AU-rich element (RHAU) (also named DHX36 or G4R1) specificall...

We report the measurement, in a pulsed hollow-cathode discharge, of metastable quartet atoms of Li and Na. By using a tunable probe laser, population densities of 3x10(10) atoms cm(-3) and 10(11) atoms cm(-3) were measured in the Li(1s2s2p)4P degrees and Na(2p(5)3s3p)(4)D(7/2) levels, respectively. These levels are candidates for energy storage for extreme-ultraviolet lasers.

A chemoproteomic-driven approach was used to investigate the interaction network between human telomeric G-quadruplex DNA and nuclear proteins. We identified novel G-quadruplex binding partners, able to recognize these DNA structures at chromosome ends, suggesting a possible, and so far unknown, role of these proteins in telomere functions.

We have carried out a survey of potential quadruplex structure sequences (PQSS), which occur in the immediate upstream region (500 bp) of human genes. By examining the number and distribution of these we have established that there is a clear link between them and the occurrence of the SP1-binding element 'GGGCGG', such that a large number of upstream PQSS incorporate the SP1-binding element.