O(6)-alkylguanine-DNA alkyltransferase (AGT) is a single-cycle DNA repair enzyme that removes pro-mutagenic O(6)-alkylguanine adducts from DNA. Its functions with short single-stranded and duplex substrates have been characterized, but its ability to act on other DNA structures remains poorly understood. Here, we examine the functions of this enzyme on O(6)-methylguanine (6mG) adducts in the fo...

The reactivation of telomerase activity in most cancer cells supports the concept that telomerase is a relevant target in oncology, and telomerase inhibitors have been proposed as new potential anticancer agents. The telomeric G-rich single-stranded DNA can adopt in vitro an intramolecular quadruplex structure, which has been shown to inhibit telomerase activity. We used a fluorescence assay to...

This is a correction to the following paper: General peroxidase activity of a parallel G-quadruplex-hemin DNAzyme formed by Pu39WT a mixed G-quadruplex forming sequence in the Bcl-2 P1 promoter, Bo Liu, Da Li* and Hong Shang*, Chemistry Central Journal 2014, 8:43 (1 July 2014). CorrectionThis is a correction to the following paper: Generalperoxidase activity of a parallel G-quadruplex-h...

Stabilization of G-quadruplex inhibits the activity of the enzyme telomerase in cancer cells. We found LL37, a host defense human cathelicidin antimicrobial peptide, to be a potent binder of G-quadruplex structures.

Quadruplex RNAs are less well understood than their DNA counterparts, yet of potentially high biological relevance. The interactions of several quadruplex-binding ligands with telomeric RNA quadruplexes are reported and compared with their binding to the analogous DNA quadruplexes.

Background: G-quadruplex DNA structures are hypothesized to be involved in the regulation of gene expression and telomere homeostasis. The development of small molecules that modulate the stability of G-quadruplex structures has a potential therapeutic interest in cancer treatment and prevention of aging. Methods: Molecular absorption and circular dichroism spectra were used to monitor thermal ...

Interactions of porphyrin derivatives 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)-21H,23Hporphyrin (TMPyP4) and 5,10,15,20-tetrakis(N-propylpyridinium-4-yl)-21H,23H-porphyrin (TPrPyP4) with human telomeric AG3(T2AG3)3 G-quadruplex DNAs in 150 mM K -containing buffer in the presence or absence of 40% molecular crowding agent poly(ethylene glycol) (PEG 200) were studied by absorption titration f...

G-quadruplexes have shown great promise as chemotherapeutic targets, probably by inhibiting telomere elongation or downregulating oncogene expression. There have been many G-quadruplex ligands developed over the years but only a few have drug-like properties. Consequently only a few G-quadruplex ligands have entered clinical trials as cancer chemotherapeutic agents. The DNA minor groove ligand,...

Two G-quadruplex forming sequences, 5'-TGGGAG and the 17-mer sequence T30177, which exhibit anti-HIV-1 activity on cell lines, were modified using either locked nucleic acids (LNA) or via insertions of (R)-1-O-(pyren-1-ylmethyl)glycerol (intercalating nucleic acid, INA) or (R)-1-O-[4-(1-pyrenylethynyl)phenylmethyl]glycerol (twisted intercalating nucleic acid, TINA). Incorporation of LNA or INA/...

We report the NMR solution structure of the intramolecular G-quadruplex formed in human telomeric DNA in K(+). The hybrid-type telomeric G-quadruplex consists of three G-tetrads linked with mixed parallel-antiparallel G-strands, with the bottom two G-tetrads having the same G-arrangement (anti:anti:syn:anti) and the top G-tetrad having the reversed G-arrangement (syn:syn:anti:syn). The three TT...