New metal-free DNA cleaving reagent 1, 1,4,7-triazacrown (TACN) both with aminoethyl, hydroxyethyl side arms and a planar anthraquinone linked by an alkyl (1,6-hexamethylene) spacer has been synthesized and characterized by NMR and MS spectrometry. For comparison, the corresponding aminoethyl, hydroxyethyl triazacrown derivative 2 without the anthraquinone has also been synthesized. DNA-binding properties via fluorescence and CD spectroscopy indicate that the binding affinity of 1 with DNA is much stronger than that of 2. Agarose gel electrophoresis was used to assess plasmid pUC19 DNA cleavage. Kinetic data of DNA cleavage promoted by 1, 2 and parent triazacrown (TACN) 3 under physiological condition give the 15-fold and 234-fold rate acceleration of compound 1 over 2 and parent triazacrown 3. Radical scavenger inhibition study suggests that DNA cleavage promoted by 1 may be a non-oxidative pathway through the transphosphorylation and then hydrolysis. The dramatic rate acceleration is due not only to the anthraquinone moiety of compound 1 intercalating into DNA base pairs via stacking interaction, but also the cooperative catalysis of the nucleophilic hydroxyl and the electrophilic ammonium group for the cleavage of phosphodiester of DNA.

No abstract

No abstract