61 research outputs found

    Mesoscale DNA structural changes on binding and photoreaction by Ru(TAP)2(PHEHAT)2+.

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    We used scanning force microscopy (SFM) to study the binding and excited state reactions of the intercalating photoreagent Ru[(TAP) 2PHEHAT] 2+ (TAP = 1,4,5,8-tetraazaphenanthrene; PHEHAT = 1,10- phenanthrolino[5,6-b]1,4,5,8,9,12-hexaazatriphenylene) with DNA. In the ground state, this ruthenium complex combines a strong intercalative binding mode via the PHEHAT ligand, with TAP-mediated hydrogen bonding capabilities. After visible irradiation, SFM imaging of the photoproducts revealed both the structural implications of photocleavages and photoadduct formation. It is found that the rate of photocleaving is strongly increased when the complex can interact with DNA via hydrogen bonding. We demonstrated that the photoadduct increases DNA rigidity, and that the photo-biadduct can crosslink two separate DNA segments in supercoiled DNA. These mechanical and topological effects might have important implications in future therapeutic applications of this type of compounds. © 2012 American Chemical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

    Oxidizing Ru(II) complexes as irreversible and specific photo-cross-linking agents of oligonucleotide duplexes.

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    Oxidizing polyazaaromatic Ru(II) complexes containing two TAP ligands (TAP = 1,4,5,8-tetraazaphenanthrene) are able under illumination to cross-link irreversibly the two strands of an oligonucleotide (ODN) duplex by covalent bond formation. The cross-linking proceeds by two successive absorptions of a photon. An adduct of the metallic complex on a guanine (G) base of one ODN strand is first photoproduced, followed by a second photoaddition of the same Ru species to a G base of the complementary strand, provided that the two G moieties are separated by 0 or 1 base pair. These two processes lead to the cross-linking of the two strands. Such a photo-cross-linking is easily detected with [Ru(TAP)(2)(phen)](2+) (1; phen = 1,10-phenanthroline) and [Ru(HAT)(2)(phen)](2+) (2; HAT = 1,4,5,8,9,12-hexaazatriphenylene), whereas it is not observed with [Ru(TAP)(2)TPAC](2+) (3; TPAC = tetrapyridoacridine) at the same level of loading of the duplex by 3. With a concentration of 3 similar to that of 1 and 2, when the loading of the duplex by 3 is much more important than with 1 and 2, the photo-cross-linking with 3 can thus also be observed. As 3 intercalates its TPAC ligand into the base pairs stack, its mobility is restricted in the duplex. In contrast, 1 and 2 can adopt different geometries of interaction, which probably facilitate the photo-cross-linking.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe
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