title: DNA binding and photocleavage specificities of a group of tricationic metalloporphyrins.
abstract: The interactions of 5,10,15-tris(1-methylpyridinium-4-yl)-20-(4-hydroxyphenyl)porphyrinatozinc(II) Zn[TMPyHP](3+) (2) along with Cu[TMPyHP](3+) (3), Co[TMPyHP](4+) (4), Mn[TMPyHP](4+) (5) and the free base porphyrin H(2)[TMPyHP](3+) (1) with duplex DNA have been studied by using a combination of absorption, fluorescence titration, surface-enhanced Raman spectroscopy (SERS), induced circular dichroism (ICD) spectroscopy, thermal DNA denaturation, viscosity measurements as well as gel electrophoresis experiment. Their binding modes and intrinsic binding constants (K(b)) to calf DNA (CT DNA) were comparatively studied and were found significantly influenced by different metals coordinated with the porphyrin plane. Except 3, which has four-coordination structure at the metal, all the metal derivatives showed non-intercalative DNA-binding mode and lower K(b) than the free base porphyrin 1, most probably due to the steric hindrance results from the axial ligands of the inserted metals which are five or six-coordination structures. Meanwhile, the insertion of metals into cationic porphyrin greatly removed the self-aggregation of the metal-free porphyrins, and thus fully enhanced the singlet oxygen ((1)O(2)) productivities in the DNA photocleavage experiments. Therefore, these metalloporphyrins have comparable DNA cleavage ability with the free base porphyrin.
authors.affiliation: MOE Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, PR China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhao
authors.forename: Jin-Wang
authors.initials: JW
authors.lastname: Huang
authors.forename: Wen-Jie
authors.initials: WJ
authors.lastname: Mei
authors.forename: Juan
authors.initials: J
authors.lastname: He
authors.forename: Liang-Nian
authors.initials: LN
authors.lastname: Ji
mesh_terms: D002412:Cations / Q000737:chemistry*; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D053837:DNA Cleavage; D008665:Metalloporphyrins / Q000737:chemistry / Q000378:metabolism; D015394:Molecular Structure; D009691:Nucleic Acid Denaturation; D010777:Photochemistry / Q000379:methods*; D011166:Porphyrins / Q000737:chemistry / Q000378:metabolism; D013057:Spectrum Analysis / Q000379:methods; D014783:Viscosity
chemical_list: D002412:Cations; D008665:Metalloporphyrins; D011166:Porphyrins; D004247:DNA