Study on the binding mode of zinc(II) protoporphyrin and ctDNA in water.
Spectroscopic property of a commercially available luminescent reagent Zinc(II) protoporphyrin (ZnPP) was studied. Dissociation constants of the two protons on the peripheral groups of porphyrin ring of ZnPP were determined as pK(a1)=6.31, pK(a2)=9.37. Binding evidence of ZnPP with ctDNA was found by the phosphorescence intensity change on a filter paper around pH 6.5-9.3 with the association constant being 9.1x10(3) dm(3)/mol. A novel binding mode for ZnPP and calf thymus DNA (ctDNA) suggested that the monomer ZnPP which has no axial coordination, slips into the groove of DNA and interacts with the bases of polynucleotide by zinc coordination and hydrogen bonding between H atom on carboxyl group of ZnPP and O atom on the bases.
Department of Chemistry, Tsinghua University, Beijing 100084, China. tongaj@chem.tsinghua.edu.cn
Ai-jun
AJ
Tong
Chun-yuan
CY
Tong
Qing-yi
QY
Yang
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D004247:DNA / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D011524:Protoporphyrins / Q000737:chemistry*; D013053:Spectrophotometry; D013950:Thymus Gland; D014867:Water
D011524:Protoporphyrins; D014867:Water; C017803:zinc protoporphyrin; D004247:DNA