Copper and zinc complexes of a diaza-crown ether as artificial nucleases for the efficient hydrolytic cleavage of DNA

Artificial nucleases are a kind of new non-enzymatic breakage tool, which mimic the function of a restricted enzyme and can catalyze nucleic acid cleavage highly efficiently and selectively. Some metal complexes are highly efficient cleavage agents for DNA. In this report, a diaza-crown ether (L) was synthesized and its copper and zinc complexes (CuL and ZnL) were prepared to serve as artificial nucleases. The compositions of the two metal complexes were confirmed by LC-MS analysis, and the nuclease activity of the complexes towards pUC19 DNA cleavage was studied using agarose gel electrophoresis. The results indicate that the two metal complexes can accelerate the breakage of DNA from the supercoiled (form I) to the nicked form (form II) under appropriate conditions; the optimal pH value for the DNA catalytic cleavage is 8.01 for both CuL and ZnL; the complex ZnL was a better catalyst in the DNA cleavage process than the complex CuL at low concentrations; and unreactive m-hydroxo dimers were formed hampering the DNA cleavage process at high concentrations. In the presence of free radical scavengers, the supercoiled plasmid DNA cleavage catalyzed by these complexes has been performed and the catalytic mechanism has been investigated.