Interactions of Meso-tetra-(4-N-oxyethylpyridyl) Porphyrin, Its 3-N Analog and Their Metallocomplexes with Duplex DNA

Abstract

Interactions of meso-tetra-(4-N-oxyethylpyridyl) porphyrin (TOEPyP(4)), its 3-N analog (TOEPyP(3)) and their Co, Cu, Ni, Zn metallocomplexes with duplex DNA have been investigated by uv/visible absorbance and circular dichrosim spectroscopies. Results reveal the interactions of these complexes with duplex DNA are of two types. (1) External binding of duplex DNA by metalloporphyrins containing Zn and Co, and (2) Binding of duplex DNA both externally and internally (by intercalation) by porphyrins not containing metals, and metalloporphyrins containing Cu and Ni. Results indicate that (4N-oxyethylpyridyl) porphyrins intercalate more preferably in the structure of duplex DNA and have weaker external binding than 3N-porphyrins.

Thermodynamics of interaction ofmeso-tetra-(4N-oxyethylpyridyl) porphyrin and its Cu(II)- and Co(II)- containing derivatives with A and B forms of DNA

“…2b) are characterized by two (positive and negative) bands with the same low intensity and the form of ICD spectra which does not change by the increase in porphyrin concentration. These ICD spectra in the porphyrin region differ from previous studies, because they were carried out at high ionic strengths [17]. The appearance of bisignate ICD spectra of TOEPyP4/B-DNA complex indicates that the intercalative binding type also takes place at the formation of this complex.…”

“…Our previous studies of interaction of water soluble meso-tetra-(4N-oxyethylpyridyl) porphyrin and its Cu(II)-and Co(II)-containing derivatives (CuTOEPyP4 and CoTOEPyP4) with B-DNA of calf thymus have shown that at high ionic strengths TOEPyP4 and CuTOEPyP4 prefer the intercalative binding mechanism, and CoTOEPyP4, which has an axial ligand, binds only externally in the major groove of DNA [17][18][19]. In this paper, the comparative study of interaction of these porphyrins with A-and Bform DNA at low ionic conditions is conducted.…”

Zn Ions Change Binding Mode of TOEPyP4 with DNA and Cause DNA Transition from B to C and Zn-Like Conformations

“…This unique properties of TMPyP4 to selectively bind to GC-rich DNA sites capable to form G-quadruplexes may be lost if TMPyP4 binds to divalent ions, due to which porphyrin structure becomes asymmetric. It was also shown that the axial ligand ZnTOEPyP4 (meso-tetra(4-N-oxyethylpyridil)) performed an external binding mode and initiated a strong increase of DNA thermopstability [6], as well as transition from B to Z-like conformation [7]. It was also shown that high concentrations of TOEPyP4 initiated transformation of poly[d(A-T)d(A-T)] but not ply(G-C) into Z-like conformation, when TOEPyP4/ DNA = 0.23 [8,9].…”

CD and DSC Investigation of Individual and Complex Influence of Meso-Tetra(4-Oxiethylpyridil) Porphyrin (TOEPyP4) and Its Zn-Complex on DNA

“…On the basis of some experimental data [6,[11][12][13][14]23], we propose the following explanation. TOEPyP4 that intercalates into the GC rich sites induces not only local damages, but also causes distortion of the standard B-form of DNA [6,23].…”

“…In the given work we tried to characterize the joint influence of two different conformational conditions of TOEPyP4-plane porphyrin and its nonplane Zn-complex. TOEPyP4 is an analogue of TMPyP, according to its physical and chemical properties [14,15].…”