DNA quadruplexes

Gavathiotis E et al. (2003) Drug recognition and stabilisation of the parallel-stranded DNA quadruplex d(TTAGGGT)4 containing the human telomeric repeat. J Mol Biol 334(l) 25-36... 

It has been suggested that zinc ions prevent formation of DNA quadruplexes containing guanine quartets by binding to the guanine N7 and 06. The quadruplexes are believed to be important to a number of areas of the genome including telomeres.179... 

The variations in the probability of damage induction calculated with RADACK are well reflected in the variation of frank SSBs and damaged bases (as expressed by ALS) for different forms of DNA B-DNA (Fig. 12.5), Z-DNA (Tartier et al. 1994 Fig. 12.6) and for a DNA quadruplex (Tartier et al. 1998). The yield of OH-induced frank SSBs of various topoisomers of DNA minicircles is the same (Culard et al. 1994). It has been concluded that the accessibility of H4 is already sufficient in the relaxed topoisomer that an increase in accessibility in the T-2 topoisomer would be without effect. 

E. Skripkin and D.J. Patel, V-shaped scaffold A new architectural motif identified in an A.(G.G.G.G) pentad-containing dimeric DNA quadruplex involving stacked G anti).G anti).G anti).G syn) tetrads, J. Mol. Biol., 2001, 311, 1063-1079. 

A. Kettani, S. Bouaziz, A. Gorin, H. Zhao, R.A. Jones and D.J. Patel, Solution structure of a Na cation stabilized DNA quadruplex containing... 

S. Bouaziz, A. Kettani and D.J. Patel, A K cation-induced conformational switch within a loop spanning segment of a DNA quadruplex containing G-G-G-C repeats, J. Mol. Biol, 1998, 282, 637-652. 

R. Jones and D.J. Patel, A double chain reversal loop and two diagonal loops define the architecture of a unimolecular DNA quadruplex containing a pair of stacked G syn).G syn).G anti).G anti) tetrads flanked by a... 

P. Hazel, G.N. Parkinson and S. Neidle, Topology variation and loop structural homology in crystal and simulated structures of a bimolecular DNA quadruplex, J. Am. Chem. Soc., 2006, 128, 5480-5487. 

The anthraquinone derivative (2) represents the first example from 1997, with numerous others following in rapid succession, including the dibenzo-phenanthroline derivatives and tri-substituted acridines (3), which were reported to inhibit telomerase action in tumour cell lines with IC50 values of up to 28 and 60 nM, respectively. The tri-substituted acridines (3) were developed from the simple acridine (4) on the basis of structure-based design principles to maximise the quadruplex binding affinity. Thus, inhibition of telomerase by these compounds appears to be correlated to selective stabilisation of the human DNA quadruplex structure. Tetra-(A-methyl-4-pyridyl)-porphyrins... 

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