title: Binding properties of Ru(II) polypyridyl complexes with poly(U)·poly(A)*poly(U) triplex: the ancillary ligand effect on third-strand stabilization.
abstract: The binding properties of [RuL(2)(mip)](2+) {where L is 1,10-phenanthroline (phen) or 4,7-dimethyl-1,10-phenanthrollne (4,7-dmp) and mip is 2'-(3",4"-methylenedioxyphenyl)imidazo[4',5'-f][1,10]phenanthroline} with regard to the triplex RNA poly(U)·poly(A)*poly(U) were investigated using various biophysical techniques and quantum chemistry calculations. In comparison with [Ru(4,7-dmp)(2)(mip)](2+), remarkably higher binding affinity of [Ru(phen)(2)(mip)](2+) for the triplex RNA poly(U)·poly(A)*poly(U) was achieved by changing the ancillary ligands. The stabilization of the Hoogsteen-base-paired third strand was improved by about 10.9 °C by [Ru(phen)(2)(mip)](2+) against 6.6 °C by [Ru(4,7-dmp)(2)(mip)](2+). To the best of our knowledge, [Ru(phen)(2)(mip)](2+) is the first metal complex able to raise the third-strand stabilization of poly(U)·poly(A)*poly(U) from 37.5 to 48.4 °C. The results reveal that the ancillary ligands have an important effect on third-strand stabilization of the triplex RNA poly(U)·poly(A)*poly(U) when metal complexes contain the same intercalative ligands.
authors.affiliation: College of Chemistry, Xiangtan University, Xiangtan 411105, People's Republic of China. lfwyxh@yahoo.com.cn
authors.forename: Li-Feng
authors.initials: LF
authors.lastname: Tan
authors.forename: Ling-Jun
authors.initials: LJ
authors.lastname: Xie
authors.forename: Xiao-Nan
authors.initials: XN
authors.lastname: Sun
mesh_terms: D008024:Ligands; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D009942:Organometallic Compounds / Q000737:chemistry* / Q000378:metabolism*; D011131:Polyribonucleotides / Q000737:chemistry* / Q000378:metabolism*; D011789:Quantum Theory; D020871:RNA Stability; D012428:Ruthenium / Q000737:chemistry*; D013696:Temperature; D014783:Viscosity
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D011131:Polyribonucleotides; C063025:poly(U).poly(A).poly(U); D012428:Ruthenium