Binding of platinum(II) intercalation reagents to deoxyribonucleic acid. Dependence on base-pair composition, nature of the intercalator, and ionic strength

Abstract

The DNA binding of three platinum(II) intercalation reagents has been studied and found to depend upon base composition, the nature of the intercalator, and the ionic strength of the solvent medium. In 0.2 M NaCl, binding data for calf thymus DNA show the association constants to be approximately 10(4) M-1. The binding constants decrease in the order [(o-phen)Pt(en)]2+ greater than or equal to [(terpy)Pt(HET)]+ greater than [(bipy)Pt(en)]2+. The number of available intercalation sites for the doubly charged intercalators is only 70% of the number expected from the nearest-neighbor exclusion model. Binding of [(o-phen)Pt(en)]2+ and [(terpy)Pt(HET)]+ to various DNAs depends linearly on G.C content. Both reagents exhibit essentially the same degree of G.C specificity. Intercalative binding is a function of ionic strength. Increasing the salt concentration minimizes the importance of metallointercalator charge, and extrapolation to 1 M salt reveals the intercalative abilities, as reflected in binding constants, to be equivalent for [(terpy)Pt(HET)]+ and [o-phen)Pt(en)]2+ and about 1 order of magnitude less than that of ethidium.

Structures and Interaction with DNA of Ternary Palladium(II) Complexes: [Pd(Gly)(X)] (Gly=Glycine; X=2,2′-Bipyridine, 1,10-Phenanthroline and 2,2′-Bi-pyridylamine)

“…These electrophoretic results suggest that all of the complexes enhance the oxidative cleavage of SC DNA in the presence of H 2 O 2 and ascorbic acid, although a little cleavage occures even in the presence of H 2 O 2 and ascorbic acid without the complexes. Up to the present, the antibiotic activity of Pd(II) complexes with heterocyclic ligands has been reported in vivo and explained by the intercalation and/or groove binding models, 15,32,33,37,39) although the precise mechanism is not yet clear. Recently, the cleavage of Form I to Form II of the pUC19 plasmid DNA by the intercalative Pd(II) complex, [Pd 2 (m-bzta) 4 ] · 1.5DMSO (where bztaϭbenzothiazole-2-thiolate) 12) has been reported in vitro.…”

“…The electrophoretic migration patterns for the cleavage of SC DNA are usually characterized by three forms (Form I, II, III). 28,29,33,38) The fastest migration of the electrophoretic pattern is called Form I, which reflects super coiled DNA. A slower migration pattern is Form II, which reflects nicked circular DNA.…”

Crystal structure, supramolecular self-assembly and interaction with DNA of a mixed ligand manganese(II) complex

“…[8][9][10][11][12][13] A metallointercalator binds DNA through the insertion of a planar polycyclic aromatic ligands, p-stacking in between two base pairs. 14,15 So the binding site and the intensity of a metallointercalator can be tuned by the metal coordination center and chelate ligand.…”

Analysis of DNA structural patterns and sequence organization at the larval cuticle locus in Drosophila melanogaster.

“…There are two lines of evidence which seem to argue against the simple hypothesis that the action of these reagents is dominated by adenine-thymine richness alone. First, whereas micrococcal nuclease shows a preference for adenine-thymine-rich sequences, data on the binding preferences of 1,10-phenanthroline and other intercalating compounds indicate some preference for G-C-rich DNA (5,8,16). In both cases, however, attempts to identify a consensus recognition site at the sequence level have been confounded by the strong influence of neighboring sequences.…”