Albany 2015:Book of Abstracts
June 9-13 2015
©Adenine Press (2012)
The Comparative Study of H2TOEPyP4 and CoTOEPyP4 Porphyrins with A-DNA
The peculiarities of binding the water-soluble meso-tetra-(4N-oxyethylpyridyl) porphyrin (H 2TOEPyP4) and its Co-containing form (CoTOEPyP4) with A-DNA have been studied by UV-VIS spectrophotometry and circular dichroism(CD) methods. All studies were performed in diluted solution of BPSE buffer (BPSE= 6mM Na2HPO2+2mM NaH2PO2+185mM NaCl+0.1mM EDTA), pH 7.0, ionic strength [Na+]=10-3M. The results indicated that the presence of Co in porphyrin ring was decreasing binding constant ten times as compared with H2TOEPyP4 porphyrin. The induced CD spectra was shown(Pasternack, 2003), that H2TOEPyP4 and CoTOEPyP4 porphyrins interact with A-DNA only through external groove binding, while H2TOEPyP4 interact with B-DNA by intercalative mode at small porphyrin-DNA ratio, which consequently changes into outside stacking mode at higher rations(Avetisyan, 2014). From the dependencies of binding constants (lnKb ) versus 1/T we evaluated the free binding energies of complexation (ΔGb), enthalpies (ΔHb) and entropies (ΔSb). The increasing entropy (ΔSb) shown that the nature of interaction of porphyrin with A-DNA is predominately hydrophobic. Therefore H2 TOEPyP4 and CoTOEPyP4 porphyrins interact with A-DNA through external groove binding.
This research has been supported by SCS of MES of RA 14A-1f79 and 13-1F094.
Avetisyan A.A. Interaction of TOEPyP4 Porphyrin with A Form of DNA. Proceedings of the Yerevan State University. Physical and Mathematical Sciences, 2014, No.3, p. 43-48.
Department of Molecular Physics