Medicinal chemistry of plasmid DNA with peptide nucleic acids: A new strategy for gene therapy

Mechanism of DNA Cleavage Catalysed by the System Comprising an Unsaturated Tetraaza Macrocycle and La(III) and Ce(III) Ions

In order to further the design of efficient artificial nuclease models for hydrolytic cleavage of DNA, the catalytic system made from an unsaturated tetraaza macrocycle and La(III) and Ce(III) ions was constructed and used as catalyst in the cleavage of plasmid PUC19 DNA. The interactions of these catalytic systems with plasmid PUC19 DNA has been investigated by UV-Vis absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry and gel electrophoresis. The results show that the combination of the catalytic system with DNA involves electrostatic binding through the phosphodiester linkages of DNA. The gel electrophoresis results also showed that supercoiled PUC19 plasmid DNA (cccDNA) was converted to the nicked form of DNA (ocDNA) under a nitrogen atmosphere. On the basis of these results, a mechanism for the catalytic cleavage of DNA is proposed.