Development of viscometric methods for studying the interaction of various porphyrins with DNA. Part III: Meso-tetra-(3N-alylpyridyl)porphyrin and its Cu-, Co- and Zn-containing derivatives

Abstract

Present research continues the development of viscometry method for studying porphyrin–DNA interactions.Water soluble cationic meso-tetra-(3[Formula: see text]-alylpyridyl) porphyrin (H2TAlPyP3) and its Cu-, Co- and Zn-containing derivatives were studied using UV-vis absorption spectroscopy and viscometry in order to clarify the effect of chemical structure (presence of double bond in structure of a side radical) of porphyrins and ability to affect the DNA structure. Their binding constant ([Formula: see text] and stoichiometry ([Formula: see text] were determined based on the absorbance spectra for each DNA–porphyrin complex. The results were compared with results of previously conducted similar studies with meso-tetra-(3[Formula: see text]-hydroxyethylpyridyl) porphyrins. It was shown, that the planar porphyrins H2TAlPyP3 and CuTAlPyP3 interact with DNA predominantly by intercalation at low relative concentrations of [Formula: see text](([Formula: see text] [Formula: see text] [Porphyrin]/[DNA])) and by external binding mode at high values of [Formula: see text], whereas the change of chemical structure of peripheral radicals of porphyrins does not absolutely affect on the mechanism of interaction of outside binders CoTAlPyP3 and ZnTAlPyP3 with DNA.