Number of binding sites of DNA and polynucleotides with tris(2,2′-bipyridyl)ruthenium(II) cations

✍ Scribed by Czeslaw Stradowski; Helmut Görner; Leslie J. Currell; Dietrich Schulte-Frohlinde

• Publisher: Wiley (John Wiley & Sons)
• Year: 1987
• Tongue: English
• Weight: 761 KB
• Volume: 26
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360260203

✦ Synopsis

The binding of tris(2,2'-bipyridyl)ruthenium(II) cations [Ru(bpy)$+ ] with single-and doublestranded (ss and ds) DNA, and the polynucleotides poly(A), poly(C), poly(G), poly(I), poly(1) .

poly(C), and poly(U), was studied in aqueous solution. Steady-state electrical conductivity measurements with the polynucleotides, ssDNA, and dsDNA reveal that approximately three nucleotides offer one binding site. This may be compared with the ratio [nucleotide]/[Mg*+] of 2.4 : 1 for dsDNA. After laser excitation (353 nm), the luminescence of Ru(bpy)$+ bound to nucleic acids shows two decay components. The contribution of the fast component, which is interpreted as resulting from quenching processes of the absorbed ruthenium complex, exhibits a maximum with increasing [nucleotide]/[Ru(bpy)$+] at a ratio of about three to one. Bound Ru(bpy)E' can be released from the strand by addition of NaC10, [half-concentration: 2.5 and 2 10 m M for poly(U) and dsDNA, respectively].