title: A rigid dinuclear ruthenium(II) complex as an efficient photoactive agent for bridging two guanine bases of a duplex or quadruplex oligonucleotide.
abstract: The rigid dinuclear [(tap)(2)Ru(tpac)Ru(tap)(2)](4+) complex (1) (TAP=1,4,5,8-tetraazaphenanthrene, TPAC=tetrapyridoacridine) is shown to be much more efficient than the mononuclear bis-TAP complexes at photodamaging oligodeoxyribonucleotides (ODNs) containing guanine (G). This is particularly striking with the G-rich telomeric sequence d(T(2)AG(3))(4). Complex 1, which interacts strongly with the ODNs as determined by surface plasmon resonance (SPR) and emission anisotropy experiments, gives rise under illumination to the formation of covalent adducts with the G units of the ODNs. The yield of photocrosslinking of the two strands of duplexes by 1 is the highest when the G bases of each strand are separated by three to four base pairs. This corresponds with each Ru(tap)(2) moiety of complex 1 forming an adduct with the G base. This separation distance of the G units of a duplex could be determined thanks to the rigidity of complex 1. On the basis of results of gel electrophoresis, mass spectrometry, and molecular modelling, it is suggested that such photocrosslinking can also occur intramolecularly in the human telomeric quadruplex d(T(2)AG(3))(4).
authors.affiliation: Organic Chemistry and Photochemistry, Université libre de Bruxelles, 50 avenue F.D. Roosevelt, 1050 Bruxelles, Belgium.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Rickling
authors.forename: Liana
authors.initials: L
authors.lastname: Ghisdavu
authors.forename: Frédéric
authors.initials: F
authors.lastname: Pierard
authors.forename: Pascal
authors.initials: P
authors.lastname: Gerbaux
authors.forename: Mathieu
authors.initials: M
authors.lastname: Surin
authors.forename: Pierre
authors.initials: P
authors.lastname: Murat
authors.forename: Eric
authors.initials: E
authors.lastname: Defrancq
authors.forename: Cécile
authors.initials: C
authors.lastname: Moucheron
authors.forename: Andrée
authors.initials: A
authors.lastname: Kirsch-De Mesmaeker
mesh_terms: D001483:Base Sequence; D003432:Cross-Linking Reagents / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D004586:Electrophoresis; D006147:Guanine / Q000737:chemistry*; D008024:Ligands; D013058:Mass Spectrometry; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010777:Photochemistry; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D003432:Cross-Linking Reagents; D008024:Ligands; D009841:Oligonucleotides; D009942:Organometallic Compounds; D006147:Guanine; D012428:Ruthenium; D004247:DNA