Synthesis, DNA recognition and cleavage studies of novel tetrapeptide complexes, Cu(II)/Zn(II)-Ala-Pro-Ala-Pro.

New tetrapeptide complexes Cu(II)·Ala-Pro-Ala-Pro (1) and Zn(II)·Ala-Pro-Ala-Pro (2) were synthesized from the reaction of tetrapeptide, Ala-Pro-Ala-Pro and CuCl2/ZnCl2 and were thoroughly characterized by elemental analysis, IR,(1)H and (13)C NMR (in case of 2), ESI-MS, UV and molar conductance measurements. The solution stability study was carried out employing UV-vis absorption titrations over a broad range of pH which suggested the stability of the complexes in solution. In vitro interaction of complexes 1 and 2 with CT-DNA was studied employing UV-vis, fluorescence, circular dichroic and viscometry studies. To throw insight into molecular binding event at the target site, UV-vis titrations of 1 and 2 with mononucleotides of interest viz.; 5'-GMP and 5'-TMP were carried out. Cleavage activity of the complexes with pBR322 plasmid DNA was evaluated by agarose gel electrophoresis and, the electrophoresis pattern demonstrated that both the complexes 1 and 2 are efficient cleavage agents. Further, the Cu(II) complex displayed efficient oxidative cleavage of supercoiled DNA while various reactive oxygen species are responsible for the cleavage in Zn(II) complex.