Synergetic DNA-cleaving activities of the metal complexes of a polyether-tethered pyrrole-polyamide dimer

A simple polyether-tethered pyrrole-polyamide dimer 1 was synthesized in 50% yield from the reaction of 2,2,2-trichloro-1-(1-methyl-4-nitro-1H-pyrrol-2-yl)ethanone with 2,2'-[1,2-ethanediylbis(oxy)]bisethanamine, and fully characterized on the basis of ¹H- and ¹³C-NMR, MS, HR-MS, and IR data. Agarose gel-electrophoresis study of the cleavage of plasmid pBR322 DNA by the complexes of compound 1 with seven metal ions indicated that most of the metal complexes were capable of efficiently cleaving DNA at pH 7.0 and 37°. Among them, the Cu(II) complex exhibited the highest activity, with the maximal catalytic rate constant k(max) and Michaelis constant K(M) being 5.61 h⁻¹ and 7.30 mM, respectively. Spectroscopic, ESI-MS, ethidium-bromide (EB) displacement, and viscosity experiments indicated that compound 1 could form a 1 : 1 complex with Cu(II) ion, and that this complex showed moderate binding affinity toward calf-thymus DNA.