College of Chemistry, Xiangtan University, Xiangtan 411105, People's Republic of China.
Academic Affairs Office, Xiangtan University, Xiangtan 411105, People's Republic of China.
J Inorg Biochem. 2021 Jan;214:111301. doi: 10.1016/j.jinorgbio.2020.111301. Epub 2020 Nov 4.
Two chiral Ru(II) polypyridyl complexes, Δ-[Ru(bpy)(6-F-dppz)] (Δ-1; bpy = 2,2'-bipyridine, 6-F-dppz = 6-fluorodipyrido[3,2-a:2',3'-c]phenazine) and Λ-[Ru(bpy)(6-F-dppz)] (Λ-1), have been synthesized and characterized as binders for the RNA poly(U)•poly(A)*poly(U) triplex and poly(A)•poly(U) duplex in this work. Analysis of the UV-Vis absorption spectra and fluorescence emission spectra indicates that the binding of intercalating Δ-1 with the triplex and duplex RNA is greater than that of Λ-1, while the binding affinities of the two enantiomers to triplex structure is stronger than that of duplex structure. Fluorescence titrations show that the two enantiomers can act as molecular "light switches" for triple- and double-helical RNA. Thermal denaturation studies revealed that that the two enantiomers are more stable to Watson-Crick base-paired double strand of the triplex than the Hoogsteen base-paired third strand, but their stability and selectivity are different. For Δ-enantiomer, the increase of the thermal stability of the Watson-Crick base-paired duplex (13 °C) is slightly stronger than of the Hoogsteen base-paired strand (10 °C), displaying no obvious selectivity. However, compared to the Hoogsteen base-paired strand (5 °C), the stability of the Λ-enantiomer to the Watson-Crick base-paired duplex (13 °C) is more significant, which has obvious selectivity. The overall increase in viscosity of the RNA-(Λ-1) system and its curve shape are similar to that of the RNA-(Δ-1) system, suggesting that the binding modes of two enantiomers with RNA are intercalation. The obtained results in this work may be useful for understanding the binding differences in chiral Ru(II) polypyridyl complexes toward RNA triplex and duplex.
两种手性 Ru(II) 多吡啶配合物，Δ-[Ru(bpy)(6-F-dppz)]（Δ-1；bpy=2,2'-联吡啶，6-F-dppz=6-氟二吡啶并[3,2-a:2',3'-c]吩嗪）和 Λ-[Ru(bpy)(6-F-dppz)]（Λ-1），已被合成并用作本工作中 RNA 聚（U）•聚（A）*聚（U）三聚体和聚（A）•聚（U）双链的结合物进行了表征。紫外可见吸收光谱和荧光发射光谱分析表明，与三聚体和双链 RNA 结合时，嵌入型 Δ-1 的结合大于 Λ-1，而两种对映异构体与三聚体结构的结合亲和力强于双链结构。荧光滴定表明，两种对映异构体可以作为三螺旋和双螺旋 RNA 的分子“光开关”。热变性研究表明，两种对映异构体与三聚体的 Watson-Crick 碱基对双链比 Hoogsteen 碱基对第三链更稳定，但它们的稳定性和选择性不同。对于 Δ-对映异构体，Watson-Crick 碱基对双链（13°C）的热稳定性增加略强于 Hoogsteen 碱基对链（10°C），显示出没有明显的选择性。然而，与 Hoogsteen 碱基对链（5°C）相比，Λ-对映异构体对 Watson-Crick 碱基对双链（13°C）的稳定性更为显著，具有明显的选择性。RNA-(Λ-1)体系的整体粘度增加及其曲线形状与 RNA-(Δ-1)体系相似，表明两种对映异构体与 RNA 的结合方式为嵌入。本工作中获得的结果可能有助于理解手性 Ru(II) 多吡啶配合物与 RNA 三聚体和双链的结合差异。
