Luminescence of ruthenium(II) polypyridyls: evidence for intercalative binding to Z-DNA
| Autor: | Alan Friedman, Kumar, Cv, Turro, Nj, Barton, Jk |
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| Jazyk: | angličtina |
| Rok vydání: | 1991 |
| Předmět: | |
| Zdroj: | Scopus-Elsevier ResearcherID |
| Popis: | Photophysical studies have been undertaken to characterize the binding interactions of enantiomers of Ru(phen)_3^(2+), Ru(DIP)_3^(2+), and racemic Ru(bpy)_2dppz^(2+) (where phen = 1,10-phenanthroline, DIP = 4,7-diphenylphenanthroline, and dppz = dipyridophenazine) with Z-form poly d(GC). Parallel enhancements in steady state luminescent intensity and a lengthening of luminescent lifetimes are seen for ruthenium enantiomers with Z-DNA as for B-DNA but with enantioselectivities reversed. Greater enhancements are seen for delta-isomers with the right-handed helix but for lambda-isomers with the left-handed helix. Ru(bpy)_2dppz^(2+), an avid intercalator in B-DNA, displays no luminescence free in aqueous solution, but luminesces brightly bound to either B- or Z-poly d(GC). Stern-Volmer quenching studies also support the enantioselective preference in binding to B-DNA by Δ-isomers and a reversal with binding to Z-DNA preferentially by the Λ-isomers. Steady state polarization studies indicate a rigid association of the complexes with both B- and Z-DNA on the time-scale of their emission and again with symmetrical enantioselectivities for the left and right-handed helices. Given the well characterized intercalative association of the complexes with B-DNA, the parallel results seen here with Z-DNA point strongly to a comparable intercalative association with the Z-form helix. That molecules may interact with Z-DNA through intercalation has not been demonstrated previously and now requires consideration in describing the range of interactions of small molecules and proteins with Z-DNA. |
| Databáze: | OpenAIRE |
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