Interaction of MnTOEtPyP4 porphyrin with DNA

Abstract

The binding of water-soluble meso-tetra-(4N-oxyethylpyridyl) porphyrin (H₂TOEtPyP4) and its manganese (III) derivative (MnTOEtPyP4) with calf thymus DNA have been quantitatively studied using UV/Vis spectrophotometry, Circular Dichroism (CD), thermal melting curves and viscometry. The results show, that porphyrins interact with DNA via one binding mode at low relative concentrations (r) and two binding modes at high values of r. The binding constant (K_b) and stoichiometry (n) were determined from binding isotherms for both porphyrin–DNA complexes. The thermal melting analysis indicates that the double-helical structure of DNA molecules is stabilizing in presence of studied porphyrins. At certain concentrations of porphyrin, two-stage melting curves were observed, which indicates the existence of two different binding modes. Obtained results show that MnTOEtPyP4 associates with DNA duplex via outside binding mode.

Communicated by Ramaswamy H. Sarma

The interaction of cationic water-soluble meso-tetra-(4N-hydroxyethylpyridyl) porphyrin and its Mn-containing derivative with DNA.

Keywords:

• DNA
• porphyrins
• circular dichroism
• melting curves
• binding parameters
• viscosity

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Grant № 21 T‐1F244. We are thankful to the Committee of Science Republic of Armenia for financial support.