Binding of octa-plus porphyrazines to DNA.
We present a preliminary report of the interaction of octacationic N-methyl-pyridyl metalloporphyrazines, M=Cu(II) (Cupz+8) and Zn(II) (Znpz+8), with calf thymus DNA. These were monitored by electronic absorption spectroscopy, and in the case of Znpz+8, also by emission spectroscopy. These studies show that both the Cupz+8 and Znpz+8 interact strongly with DNA, and at sufficient concentrations induce a highly colored precipitate. The spectrum of Cupz+8 red-shifts as DNA is added, which is interpreted as indicative of pi stacking of the charged macrocycle as it binds electrostatically to the outside of the DNA duplex. The spectrum of Znpz+8 does not shift, indicative of simple electrostatic surface binding. The absence of stacking may be related to the presence of an axial metal-ion ligand for Znpz+8, presumably 1120, while the metal ion of Cupz+8 is four-coordinate.
Anderson
M E
ME
Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.
Barrett
A G
AG
Hoffman
B M
BM
D000818:Animals; D003300:Copper / Q000737:chemistry; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D008665:Metalloporphyrins / Q000737:chemistry / Q000378:metabolism*; D013057:Spectrum Analysis; D015032:Zinc / Q000737:chemistry
D008665:Metalloporphyrins; D003300:Copper; D004247:DNA; D015032:Zinc