title: Photo-induced DNA scission by Cu(ii)-meso-tetrakis(n-N-methylpyridiniumyl)porphyrins (n = 2, 3, 4) and their binding modes to supercoiled DNA.
abstract: The photo-induced cleavage of pGEM-7zf-NIS super-coiled DNA by Cu(ii)-meso-tetrakis(n-N-methylpyridiniumyl)porphyrins (n = 2, 3, 4 referred to as o-, m- and p-CuTMPyP, respectively) and their binding mode were investigated in this study. m-CuTMPyP was most efficient in cleavage than o- and p-CuTMPyP isomers. Cleavage was suppressed by N(2) bubbling, suggesting that the cleavage occurred by an oxidative cleavage mechanism. Sodium azide, an (1)O(2) quencher, and DMSO, a hydroxyl radical scavenger, inhibited cleavage, indicating that hydroxyl radicals and singlet oxygen were likely reactive species responsible for the cleavage. Reduced linear dichroism spectroscopy showed angles of o-CuTMPyP's electric transition moments, in which the periphery pyridinium ring was prevented from free rotation, of 59° and 61° with respect to the local DNA helix axis. The spectra of m- and p-CuTMPyP complexed with pGEM-7zf-NIS DNA were characterized by large signals in the Soret band, coincident with those of known intercalated porphyrins.
authors.affiliation: Department of Chemistry, Yeungnam University, Gyeongsan City, Gyeong-buk 712-749, Republic of Korea.
authors.forename: Nataraj
authors.initials: N
authors.lastname: Chitrapriya
authors.forename: Jongjin
authors.initials: J
authors.lastname: Park
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Hyosun
authors.initials: H
authors.lastname: Lee
authors.forename: Seog K
authors.initials: SK
authors.lastname: Kim
mesh_terms: D000042:Absorption; D003300:Copper / Q000737:chemistry*; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004278:DNA, Superhelical / Q000737:chemistry* / Q000378:metabolism; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry; D008665:Metalloporphyrins / Q000737:chemistry*; D010782:Photolysis; D019810:Sodium Azide / Q000737:chemistry; D013057:Spectrum Analysis
chemical_list: D004278:DNA, Superhelical; D016166:Free Radical Scavengers; D008665:Metalloporphyrins; C441603:meso-tetra(4-methylpyridinium)porphyrinato copper(II); D003300:Copper; D004247:DNA; D019810:Sodium Azide; D004121:Dimethyl Sulfoxide