DNA Mediated Energy Transfer from 4',6-Diamidino-2-phenylindole to Ru(II)[(l,10-phenanthroline)_2L]~(2+):Effect of Ligand Structure

摘要

It was proposed that Ru(II)[(l,10-phenanthroline)_2dipyrido[3,2-a:2',3'-c]phenazine([Ru(phen)_2DPPZ]~(2+))complexes and 4',6-diamidino-2-phenylindole(DAPI)simultaneously bind to poly[d(A-T)_2](Biophysics.J.2003,85,3865).Forster type resonance energy transfer from excited DAPI to [Ru(phen)_2DPPZ]~(2+)complexes was observed.In this study,we synthesized A-and A-[Ru(phenanthroline)_2dipyrido[3,2-a:2',3'-c]6-azaphenazine]([Ru(phen)_2DPAPZ]~(2+))at which the DNA intercalating ligand DPPZ was replaced and we studied its binding properties to poly[d(A-T)_2] in the presence and absence of DAPI using polarized spectroscopy and fluorescence techniques.All the spectroscopic properties of the [Ru(phen)_2DPAPZ]~(2+)-poly[d(A-T)_2] complex were the same in the presence and absence of DAPI that blocks the minor groove of polynucleotide,suggesting both A-and A-[Ru(phen)_2DPAPZ]~(2+)complexes are located at the major groove of poly[d(A-T)_2].On the other hand,in contrast with [Ru(phen)_2DPPZ]~(2+),both A-and A-[Ru(phen)_2DPAPZ]~(2+)exhibited almost twice the efficiency in the fluorescence quenching of DAPI that binds at the minor groove of poly[d(A-T)_2].This observation indicates that the efficiency of the Forster type resonance energy transfer can be controlled by a small change in the chemical structure of the intercalated ligand.