Effects of the fluorine substituent positions of the intercalating ligands on the binding behavior and third-strand stabilization of two Ru(II) complexes toward poly(U)?poly(A)*poly(U) triplex RNA

摘要

Abstract Two new Ru(II) polypyridyl complexes containing fluorine substituents, [Ru(bpy)2(o-fpip)]2+ (Ru1, bpy=2,2′-bipyridine, o-fpip=2-(2-fluorophenyl)imidazo[4,5-f] [1,10]phenanthroline) and [Ru(bpy)2(p-fpip)]2+ (Ru2, p-fpip=2-(4-fluorophenyl)imidazo[4,5-f] [1,10]phenanthroline) have been synthesized as binders for poly(U)?poly(A)?poly(U) triplex RNA. The binding of the two complexes with the triplex RNA has been investigated by spectroscopic methods and viscosity measurements. Analysis of the electronic absorption spectra indicates that the association of intercalating Ru2 with the triplex RNA is greater than that of Ru1, which is also supported by spectroscopic titrations and viscosity measurements. Thermal denaturation studies reflect that third-strand stabilization depend on the nature of the two complexes and Ru2 is more effective for stabilization of the triplex RNA. Circular dichroism spectra of the triplex RNA in the presence of metal complexes indicate that the binding-induced CD perturbation of the triplex structure is more obvious by Ru2. The main results obtained here suggest that the positions of fluorine substituent in the intercalating ligands have a significant effect on the two complexes stabilizing the third strand. Graphical abstract Two new Ru(II) polypyridyl complexes [Ru(bpy)2(o-fpip)]2+ (Ru1) and [Ru(bpy)2(p-fpip)]2+ (Ru2) have been synthesized as binder for poly(U)?poly(A)*poly(U) triplex. Results suggest that the two complexes stabilize the triplex via intercalation. Ru1 somewhat prefers to stabilize the Watson–Crick base pairing duplex strand rather than stabilize the third strand, while Ru2 prefers to exert a rather remarkable stabilization effect on the third strand instead of the template duplex. This observation indicates that the positions of fluorine substituent in the intercalating ligands are able to alter third-strand stabilization. Display Omitted Highlights