Structure of 9-amino-[N-(2-dimethylamino)propyl]-acridine-4-carboxamide bound to d(CGTACG)2: A comparison of structures of d(CGTACG) 2 complexed with intercalators in the presence of cobalt

Faculty of Medical and Health Sciences, University of Auckland, Окленд, Auckland, New Zealand
Acta Crystallographica Section D Biological Crystallography (Impact Factor: 2.67). 06/2004; 60(Pt 5):823-8. DOI: 10.1107/S0907444904003907
Source: PubMed


The structure of the complex formed between 9-amino-[N-(2-dimethylamino)propyl]acridine-4-carboxamide and d(CGTACG)(2) has been refined to a resolution of 1.55 A. The complex crystallized in space group C222. An asymmetric unit comprises two strands of DNA, one disordered drug molecule, two cobalt(II) ions, two magnesium ions and 32 water molecules. The DNA helices stack in continuous columns, with their four central base pairs adopting a B-like motif. The terminal G.C base pairs engage in different interactions. At one end of the duplex there is a CpG dinucleotide overlap modified by ligand intercalation and terminal cytosine exchange between symmetry-related duplexes. An intercalation complex is formed involving four DNA duplexes, four disordered ligand molecules and two pairs of base tetrads. The other end of the DNA is frayed, with the terminal guanine lying in the minor groove of the next duplex in the column. The structure is stabilized by guanine N7-cobalt(II) coordination. The structure is compared with previously published isomorphous structures of d(CGTACG)(2) complexed with intercalators in the presence of cobalt and it is concluded that the formation of this crystal form is primarily determined by DNA-DNA interactions and packing forces, rather than by special interactions between the ligand and the DNA. Given the nature of the ligands found in these complexes, the relevance of the quadruplex structure to the biological activity of those agents, known to be topoisomerase poisons, is questioned.

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Available from: Laurence Patrick George Wakelin, Jan 07, 2015
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    • "Studies on pyrazoloacridines [25], imidazoacridinones [26], anthrapyrazoles [27], acridine carboxamides [28] and triazoloacridinones [29] are the most representative examples of the research in this area. These molecules have primarily been explored as chemotherapeutic agents (anticancer, antibacterial, antiprotozoal), because of the ability of the acridine chromophore to intercalate DNA (The acridine moieties are held in place by van der Waals forces supplemented by stronger ionic bonds to the phosphate ions of the DNA backbone) and inhibit topoisomerase and telomerase enzymes [7] [28] [30]. Research continues to be focussed primarily in these areas, but latter work shows they are active also as anticholinesterase agents [30]. "
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