Albany 2015:Book of Abstracts
June 9-13 2015
©Adenine Press (2012)
The features of complexformation of poly(dI-dC) 2 with porphyrins
The features of complex formation of water soluble cationic meso-tetra-(4N-oxyethylpyridyl) porphyrin (H2 TOEPyP4) and it's Cu- and Co-derivatives with poly(dI-dC) 2 was studied by UV/Vis and CD spectroscopies. The experiments of melting of poly(dI-dC) 2 -porphyrin complexes shown that all of the porphyrins increased the thermal stability of poly(dI-dC) 2 .
All investigated porphyrins exhibit induced CD spectra (ICD) in visible range at interaction with poly(dI-dC) 2 . Binding mode with DNA was determined by sign of ICD spectra. In the case of H2 TOEPyP4 observed both ICD: slight negative band at lower relative concentrations (r<0.1) and positive band at higher relative concentrations. Such behavior is explained by a weakly pronounced intercalation of planar porphyrins H2 TOEPyP4 in double helix. In the case of Cu- and Co- derivatives observed strongly pronounced positive bands. This results suggest that all investigated porphyrins preferably binds with duplex poly(dI-dC) 2 via outside self-stacking mode [Y.B.Dalyan, G.V.Ananyan, S.G.Haroutiunian et all (2001)].
The results obtained from titration experiments were used for calculation of binding parameters: the binding constant Kb and the number of binding sites per base pair n. Calculations showed that Kb of porphyrins with poly(dI-dC) 2 is equal to 1.67x105 M-1 ; 1.58x105 M-1 and 1.04x105 M-1 for H2 TOEPyP4, CuTOEPyP4 and CoTOEPyP4, respectively. The inspection of obtained parameters n provides additional evidences for the proposed models: for H2 TOEPyP4 n~1.8, which correspond to intercalation mode, and n~0.5-1 for CuTOEPyP4 and CoTOEPyP4, which is sufficient for groove binding mode [V.G.Barkhudaryan G.V.Ananyan, Y.B.Dalyan, S.G.Haroutiunian (2014)].
This research has been supported by grants SCS of MES of RA 13-1F094.
V.G. Barkhudaryan G.V. Ananyan, Y.B. Dalyan, S.G. Haroutiunian. (2014). Development of viscometric methods for studying the interaction of various porphyrins with DNA. Part I: meso-tetra-(4N-hydroxyethylpyridyl) porphyrin and its Ni-, Cu-, Co- and Zn- containing derivatives. Journal of Porphyrins and Phthalocyanines, 18, 594-599.
Gayane V. Ananyan, Nelli H. Karapetyan, Samvel G. Haroutiunian, Yeva B. Dalyan
Chair of Molecular Physics, Faculty of Physics, Yerevan State University
1 Alex Manoogian str., 375025, Yerevan, Armenia
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