Novel DNA Cleavage System And Its Cleavage Mechanism

DNA is the main site for storage of genetic information and transmitting genetic information. It is important for biological functions. Complexes with a planar aromatic heterocyclic structure can be inserted into the base pairs of DNA, thus were used as DNA cleaving reagents. DNA cleavage reagents not only provide important information for DNA division, repair and signal transduction and also can be used as anti-cancer drugs.A novel DNA cleavage system was built up using graphene oxide (GO) with single molecular planar structure with surface functional groups, Cu2+ ions, and the copper complexes. The effect of the GO, Cu2+, Cu2+/GO, copper complexes and copper complex/ GO on DNA cleavage were systematically studied using fluorescence spectroscopic (FL) and circular dichroism (CD) studies, gel electrophoresis, and DNA thermal denaturation. We demonstrated that the GO nanosheets could intercalate efficiently into DNA molecules. Significantly, we illustrated that the scission of DNA by GO sheets combining with copper ions could take place pronouncedly. The scission of DNA by the Cu2+/GO system is critically dependent on the concentrations of GO and Cu2+ and their ratio. DNA cleavage ability exhibited by the GO with several other metal ions and the fact that Cu2+/GO cleaved DNA fragments can be partially relegated suggest that the mechanism of DNA cleavage by the GO/metal ion system is oxidative and hydrolytic. Different from the Cu2+ ions, a number of copper complexes combining with GO can cut super-coiled DNA into a linear fragment. This preliminary result reveals a new route to discovery anti-cancer drug candidates.