NDLI: Photo-reactive $Ru^{II}-oligonucleotide$ conjugates: influence of an intercalating ligand on the inter- and intra-strand photo-ligation processes

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Defrancq, Eric Moucheron, Cécile Kirsch-de Mesmaeker, Andrée Foucart, Martin Le Gac, Stéphane Gerbaux, Pascal
Description	Author Affiliation: Le Gac S ( Chimie Organique et Photochimie CP160/08, Université libre de Bruxelles, 50 avenue F.D. Roosevelt, 1050, Bruxelles, Belgium.)
Abstract	The damaging efficacy towards OligoDeoxyriboNucleotides (ODNs) of two photoreactive polyazaaromatic $ruthenium^{II}$ complexes, Ru(T) and Ru(D), has been evaluated. Both compounds correspond to the known [Ru(TAP) $_{2}(dppz)]$ $^{2+}$ complex, but they are anchored differently to a guanine -containing single strand ODN ( probe strand). This has allowed us to investigate the influence of the interactions existing between the tethered complexes and the single or double strand, on the photo-ligation processes. From melting temperature measurements of the duplex formed between these Ru-ODNs and their complementary sequence (target strand), it has been found that Ru(T) anchored via the TAP ligand interacts with the duplex by means of the intercalating dppz ligand (head on geometry), while Ru(D) anchored via the dppz ligand likely adopts a side on geometry without intercalation. Both single stranded Ru conjugates self-inhibit in the absence of their target ODN by forming exclusively a cyclic “seppuku” photo-adduct (intra-molecular photoreaction). In contrast, this intra-molecular photo-product is precluded in presence of the target strand, and the Ru-ODN sequence photo-crosslinks with the latter (inter-molecular photoreaction). Both intra- and inter- molecular processes with both complexes are efficient (80% yields) and lead to stable photo-adducts. Interestingly, detailed studies have revealed that the similar photo-damaging efficacy of crosslinking by Ru(T) and Ru(D) is a consequence of a cascade of events with compensatory effects, originating from the different geometry of interaction of the tethered complexes. Notably, antagonistic effects are present when the complex is intercalated, the guanine oxidation step being highly favoured and the recombination of the quenching products being hindered.
ISSN	14779226
Issue Number	40
Volume Number	39
e-ISSN	13645447
Journal	Dalton Trans.
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2010-10-28
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Coordination Complexes Chemistry Intercalating Agents Oligodeoxyribonucleotides Ruthenium Chemical Synthesis Ligands Phenanthrenes Photochemical Processes Spectrophotometry, Ultraviolet Journal Article Research Support, Non-U.S. Gov't
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

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