title: A comparative study of the interaction of 5,10,15,20-tetrakis (N-methylpyridinium-4-yl)porphyrin and its zinc complex with DNA using fluorescence spectroscopy and topoisomerisation.
abstract: Binding of 5,10,15,20-tetrakis (N-methylpyridinium-4-yl)porphyrin (H2TMPyP4+) and its zinc complex (ZnTMPyP4+) to DNA is demonstrated by their coelectrophoresis and by absorption and fluorescence spectroscopic methods. Topoisomerisation of pBR322 DNA shows that H2TMPyP4+ unwinds DNA as efficiently as ethidium bromide showing that it intercalates at many sites. ZnTMPyP4+ may cause limited unwinding. Marked changes in the fluorescence spectra of the porphyrins are found in the presence of DNA. The fluorescence intensity of either H2TMPyP4+ or ZnTMPyP4+ is enhanced in the presence of poly (d(A-T)), whereas in the presence of poly (d(G-C] the fluorescence intensity of ZnTMPyP4+ is only slightly affected and that of H2TMPyP4+ markedly reduced. Both the porphyrins photosensitize the cleavage of DNA in aerated solution upon visible light irradiation.
authors.forename: J M
authors.initials: JM
authors.lastname: Kelly
authors.forename: M J
authors.initials: MJ
authors.lastname: Murphy
authors.forename: D J
authors.initials: DJ
authors.lastname: McConnell
authors.forename: C
authors.initials: C
authors.lastname: OhUigin
mesh_terms: D000818:Animals; D002417:Cattle; D004247:DNA / Q000378:metabolism* / Q000528:radiation effects; D004264:DNA Topoisomerases, Type I; D004586:Electrophoresis; D008027:Light; D008652:Mesoporphyrins / Q000378:metabolism* / Q000528:radiation effects; D011119:Polynucleotides / Q000378:metabolism; D011166:Porphyrins / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013054:Spectrophotometry, Atomic; D015032:Zinc / Q000378:metabolism*
chemical_list: D008652:Mesoporphyrins; D011119:Polynucleotides; D011166:Porphyrins; C021096:tetra(4-N-methylpyridyl)porphine; D004247:DNA; D004264:DNA Topoisomerases, Type I; D015032:Zinc