Hydrolytic cleavage of DNA by a Mn(II) complex with bis(2-benzimidazolylmethyl)amine

MnL (here, L=bis(2-benzimidazolylmethyl)amine) was synthesized and characterized. The MA(II) complex acts as an artificial nuclease by effectively promoting the hydrolysis of plasmid DNA at physiological pH and temperature. The studies on mechanism of DNA cleavage by added radical scavengers, rigorously anaerobic experiments, analysis for malondialdehyde-like products, and the religation assays show that DNA cleavage mediated by MnL occurs via a hydrolytic path. Values for apparent rate constants for the decrease of supercoiled DNA (form I) and the increase of linearized DNA (form III) were obtained under different complex concentrations at physiological pH and temperature. The catalytic rate constant (K-cat) was obtained on the transformation of the Michaelis-Menten equation from a best-fit line of the apparent rate constant versus complex concentration. The estimation of K, for the decrease of form I shows a rate enhancement factor of 10(8).