Li Jia, Sun Yanmei, Xie Lingjun, He Xiaojun, Tan Lifeng
College of Chemistry, Xiangtan University, Xiangtan, PR China.
Key Lab of Environment-friendly Chemistry and Application in Ministry of Education, Xiangtan University, Xiangtan, PR China.
J Inorg Biochem. 2015 Feb;143:56-63. doi: 10.1016/j.jinorgbio.2014.12.007. Epub 2014 Dec 11.
Two new Ru(II) complexes with 1,8-naphthalimide group, Ru(phen)2(pnip) (Ru1; phen=1,10-phenanthroline, pnip=2-[N-(p-phenyl)-1,8-napthalimide]imidazo[4',5'-f][1,10]phenanthroline) and Ru(bpy)2(pnip) (Ru2; bpy=2,2'-bipyridine), have been synthesized and characterized. The interactions of Ru1 and Ru2 with the triplex RNA poly(U)•poly(A)*poly(U) (where • denotes the Watson-Crick base pairing and * denotes the Hoogsteen base pairing) were studied by various biophysical. Electronic spectra established that the binding affinity for Ru1 was greater than that for Ru2. Fluorescence and viscosity studies gave convincing evidence for a true intercalative binding of both complexes with the RNA triplex. UV melting studies confirmed that the two complexes could stabilize the triplex, whereas the effects of the two complexes on the stability of the Hoogsteen base-paired strand ploy(U) and the Watson-Crick base-paired duplex poly(U)•poly(A) of the triplex were different. In the case of Ru1, the increase of the thermal stability of the Hoogsteen base-paired strand was stronger than that of the Watson-Crick base-paired duplex. However, an opposite effect was observed in the case of Ru2. Circular dichroic studies suggested that the RNA triplex undergoes a conformational transition in the presence of Ru1, whereas the helicity of the RNA triplex still remains A-type in the presence of Ru2. The main results obtained here further advance our knowledge on the interaction of RNA triple-stranded structures with metal complexes, particularly ruthenium(II) complexes.
合成并表征了两种含1,8 - 萘二甲酰亚胺基团的新型Ru(II)配合物，即Ru(phen)2(pnip)（Ru1；phen = 1,10 - 菲咯啉，pnip = 2 - [N - (对苯基)-1,8 - 萘二甲酰亚胺]咪唑并[4',5'-f][1,10]菲咯啉）和Ru(bpy)2(pnip)（Ru2；bpy = 2,2'-联吡啶）。通过多种生物物理方法研究了Ru1和Ru2与三链RNA聚(U)•聚(A)*聚(U)（其中•表示沃森 - 克里克碱基对，*表示 hoogsteen碱基对）的相互作用。电子光谱表明Ru1的结合亲和力大于Ru2。荧光和粘度研究为两种配合物与RNA三链体的真正插入结合提供了令人信服的证据。紫外熔解研究证实这两种配合物可以稳定三链体，而这两种配合物对三链体中hoogsteen碱基配对链聚(U)和沃森 - 克里克碱基配对双链聚(U)•聚(A)稳定性的影响不同。就Ru1而言，hoogsteen碱基配对链热稳定性的增加比沃森 - 克里克碱基配对双链更强。然而，在Ru2的情况下观察到相反的效果。圆二色性研究表明，在Ru1存在下RNA三链体发生构象转变，而在Ru2存在下RNA三链体的螺旋度仍保持A型。这里获得的主要结果进一步推进了我们对RNA三链结构与金属配合物，特别是钌(II)配合物相互作用的认识。
