Gayane V Ananyan, Yeva B Dalyan, Nelli H Karapetyan, Ishkhan V Vardanyan and Samvel G Haroutiunian
Yerevan State University, Armenia
Posters & Accepted Abstracts: J Bioengineer & Biomedical Sci
The features of complex formation of water soluble cationic meso-tetra-(4N-oxyethylpyridyl) porphyrin (H2TOEPyP4) and it's Cu- and Co-derivatives with synthetic double-stranded alternating polynu├?┬Čc├?┬Čle├?┬Čo├?┬Čtide poly(dG-dC).poly(dG-dC) was studied by UV/Vis and CD spectroscopes. All investigated porphyrins exhibit induced CD spectra (ICD) in visible range at interaction with poly(dG-dC).poly(dG-dC). Binding mode with DNA was determined by sign of ICD spectra. In the case of H2TOEPyP4 and CuTOEPyP4 observed both ICD: negative band at lower relative concentrations (intercalation, r<0.1) and positive band at higher relative concentrations (outside binding mode). In the case of co-derivatives observed strongly pronounced positive bands. These results suggest that H2TOEPyP4 and ├É┬íuTOEPyP4 are intercalated into poly(dG-dC).poly(dG-dC), but ├É┬íoTOEPyP4 binds only via external manner. But in high concentration range, all porphyrins preferably binds with duplex poly(dG-dC).poly(dG-dC) via outside self-stacking mode independent of the planarity of porphyrin molecules. The binding parameters (Kb and n) provides the additional evidences for the proposed models. ├É┬óhe effectiveness of complex formation of investigated porphyrins with poly(dG-dC).poly(dGdC) are arranged as follows: H2TOEPyP4>CuTOEPyP4>CoTOEPyP4. The binding constants of the porphyrins with poly(dG-dC). poly(dG-dC) is comparable to those, obtained for the same cationic porphyrins upon interaction with DNA at the same conditions. These experimental results have demonstrated that the insertion of transition metal ions into H2TOEPyP4 changes the polynucleotide duplex binding properties and the binding characteristics of metalloporphyrins to the DNA duplex are tuned by varying the metal center. This finding is important to get some insight into porphyrin├ó┬?┬?DNA interactions at the molecular level. All experiments were performed at room temperature in a phosphate buffer 0.1 BPSE, pH 7.0, [Na+]=0.02M.
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