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

Abstract

SynopsisThe 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].

Photoreactions of Tris(2,2′‐bipyridyl)‐ruthenium(ii) With Peroxydisulfate in Deoxygenated Aqueous Solution in the Presence of Nucleic Acid Components, Polynucleotides, and Dna*

“…In previous work we have shown that under certain conditions Ru(bpy):+ is attached to nucleic acids (Stradowski et al, 1987). Under these conditions the luminescence exhibits a bi-exponential decay pattern after ns-laser excitation.…”

Spectral and redox studies on mixed ligand complexes of cobalt(III) phenanthroline/bipyridyl and benzoylhydrazones, their DNA binding and antimicrobial activity

“…The remaining benzoylhydrazone moiety is disposed along the sugar-phosphate backbone, which through polar interaction with the charged sugar-phosphates restricts the free insertion (intercalation) of the phen groups. The bpy-metal counterparts, due to non-planarity of the bpy molecule [27][28][29], binds DNA very weakly though intercalative mode due to the predominant polar interaction of the benzoylhydrazone with the negatively charged deoxyribose-phosphate backbone.…”

Detection of Chemically-Induced Damage in Layered DNA Films with Co(bpy)33+ by Square-Wave Voltammetry

“…These isotherms show that much more probe is bound to outer ds-DNA layers than outer ss-DNA layers. The Co(bpy) 3 3 binding site size for ds-DNA and ss-DNA is 3 base pairs [30,54,55]. Available DNA binding sites in the outer layer were estimated under saturation conditions using the difference in the integrated coulometric charge (Q c ) between (PDDA/DNA) 2 and PDDA/DNA/PDDA films.…”