Binding and stabilizating effect of RNA triplex poly(U)•poly(A)*poly(U) by enantiomers of ruthenium(II) polypyridyl complex [Ru(bpy)2(dppx)]2+

Two chiral ruthenium(II) polypyridyl complexes, Lambda-[Ru(bpy)(2)(dppx)](2+) (bpy = 2,2'-bipyridine, dppx = 7,8-dimethyldipyridophenazine;.-1) and.-[Ru(bpy)(2)(dppx)](2+) (Delta-1) have been synthesized and characterized in this work. Interactions of Lambda-1 and Delta-1 with the RNA triplex poly(U)center dot poly(A)*poly(U) have been investigated by various biophysical techniques. Spectrophotometric titrations and viscosity measurements suggested that enantiomers Lambda-1 and Delta-1 bind with the triplex through intercalation, while the binding strengths of the two enantiomers toward the triplex differed only slightly from each other. Fluorescence titrations showed that although enantiomers Lambda-1 and Delta- 1 exhibited molecular "light switch" effects toward the triplex, the effect of Delta-1 was more marked. Furthermore, Furthermore, thermal denaturation showed that the two enantiomers have significantly different stabilizing effects on the triplex. The obtained results indicate that the racemic complex [Ru(bpy)(2)(dppx)](2+) is similar to a non-specific metallointercalator for the triplex investigated in this study, and chiralities of Ru( II) polypyridine complexes have an important influence on the binding and stabilizing effects of enantiomers toward the triplex. Graphical abstract Two chiral ruthenium(II) polypyridyl complexes, Lambda-[ Ru(bpy)(2)(dppx)](2+) (bpy = 2,2'-bipyridine, dppx = 7,8-dimethyldipyridophenazine; Delta-1) and Delta-[Ru(bpy)(2)(dppx)](2+) (Delta-1) have been synthesized and characterized in this work. Interactions of Lambda-1 and Delta-1 with the RNA triplex poly(U)center dot poly(A)*poly(U) have been investigated by various biophysical techniques. The obtained results indicate that the racemic complex [Ru(bpy)(2)(dppx)](2+) is similar as a non-specific metallointercalator for the triplex investigated in this study, and chiralities of Ru(II) polypyridine complexes have an important influence on the binding and stabilizing effects of enantiomers toward the triplex [GRAPHICS] .