College of Chemistry, Xiangtan University, Xiangtan 411105, People's Republic of China.
School of Chemical Engineering, Xiangtan University, Xiangtan 411105, People's Republic of China.
J Inorg Biochem. 2018 Sep;186:51-59. doi: 10.1016/j.jinorgbio.2018.05.013. Epub 2018 May 24.
Two chiral ruthenium(II) complexes containing ligand dppz-COMe (dppz-11-COMe = dipyrido[3,2-a,2',3'-c]phenazine-11-carboxylic acid methyl ester), Δ-[Ru(bpy)dppz-11-COMe] (bpy = 2,2'-bipyridine; Δ-1) and Λ-[Ru(bpy)dppz-11-COMe] (Λ-1), were synthesized and characterized. The binding of the two enantiomers with the triplex RNA poly(U)•poly(A)*poly(U) was carried out by various biophysical techniques. Analysis of the absorption and fluorescence features indicates that the binding strengths of the two enantiomers toward the triplex RNA differ only slightly from each other. The total increase in viscosity and shape of the curves for the triplex RNA with Λ-1 is similar to that with Δ-1, suggesting the binding modes of two enantiomers with the triplex RNA are intercalation. Thermal melting measurements indicate that the stabilization effects clearly depended on the concentrations of Λ-1 and Δ-1. However, the third-strand stabilizing effect of Δ-1 dramatically differs from that of Λ-1 when they interact with the chiral environment of the RNA triple at pH = 7.0 and [Na] = 35 mM. Combined with the CD (CD = circular dichroism) variations of the triplex RNA with either Λ-1 or Δ-1, the reason for their different triplex stabilization effects may originate from the two enantiomers through different orientations intercalating into nucleobases of the triplex. In addition, effects of higher ionic strengths on the triplex stabilization in the absence and presence of the two enantiomers have also been studied. The results presented here may be useful for understanding the binding properties of the triplex RNA with small molecule, particularly chiral ruthenium(II) complexes.
两种手性钌（II）配合物，含有配体 dppz-COMe（dppz-11-COMe=dipyrido[3,2-a,2',3'-c]phenazine-11-羧酸甲酯），Δ-[Ru(bpy)dppz-11-COMe]（bpy=2,2'-联吡啶；Δ-1）和 Λ-[Ru(bpy)dppz-11-COMe]（Λ-1），被合成并进行了表征。通过各种生物物理技术研究了两种对映异构体与三聚体 RNA 聚（U）•聚（A）*聚（U）的结合。吸收和荧光特征的分析表明，两种对映异构体与三聚体 RNA 的结合强度彼此略有不同。Λ-1 与三聚体 RNA 结合导致的总粘度增加和曲线形状与 Δ-1 相似，表明两种对映异构体与三聚体 RNA 的结合方式是嵌入。热融测量表明，稳定化效应明显取决于 Λ-1 和 Δ-1 的浓度。然而，当它们在 pH = 7.0 和 [Na] = 35 mM 下与 RNA 三链的手性环境相互作用时，Δ-1 的第三链稳定化效应与 Λ-1 的稳定化效应明显不同。结合 CD（CD=圆二色性）变化，两种对映异构体的不同三链稳定化效应的原因可能源于它们以不同的取向嵌入三聚体的碱基中。此外，还研究了在不存在和存在两种对映异构体的情况下，较高离子强度对三聚体稳定化的影响。本文的结果可能有助于理解小分子与三聚体 RNA 的结合性质，特别是手性钌（II）配合物。
