Abstract
The binding peculiarities of the water-soluble meso-tetra-(4N-hydroxyethylpyridyl) porphyrin (H2TOEtPyP4) and its Cu- and Co-derivatives (CuTOEtPyP4 and CoTOEtPyP4) with synthetic double-stranded alternating polynucleotide poly(dG-dC).poly(dG-dC) were investigated by UV/Vis absorption and circular dichroism (CD) methods. It was shown that the porphyrins with planar structure such as H2TOEtPyP4 and CuTOEtPyP4 interact with poly(dG-dC).poly(dG-dC) via intercalation at low relative concentrations (r = [porphyrin]/[polynucleotide]), while at high r - via intercalation and external binding modes. In the case of no planar porphyrin CoTOEtPyP4 complexation occurs only by external binding mode. The binding constant Kb and the exclusion parameter n calculated for H2TOEtPyP4, CuTOEtPyP4 and CoTOEtPyP4 porphyrins with poly(dG-dC).poly(dG-dC) complexes was 1.50 x107, M−1 (n = 1.76); 9.29 x107, M−1 (n = 1.18); and 0.28 x107, M−1 (n = 2.65) correspondingly. The values of binding parameters for each porphyrin–poly(dG-dC).poly(dG-dC) complexes demonstrated good agreement with the proposed binding models.
Communicated by Ramaswamy H. Sarma
Disclosure statement
No potential conflict of interest was reported by the author(s).