DNA cleavage study using copper (II)-GlyAibHis: A tripeptide complex based on ATCUN peptide motifs

Development of new chemical nucleases is a matter of great interest because of their extensive use in biotechnology and as therapeutic agents. The ATCUN (amino terminal Cu(II) and Ni(II) binding) is a peptide motif that occurs naturally in the serum albumins. The similar peptide motif (GlyAibHis) having unnatural amino acid Aib (alpha-aminoisobutyric acid) was synthesized and its Cu(II) complex was characterized by ESI-MS and spectrophotometry studies. The reactivity of this complex toward DNA cleavage has been investigated. Cu(II)-GlyAibHis shows the DNA cleavage only in presence of mild oxidizing agents like ascorbate by an oxidative mechanism rather than hydrolytic and follows the pseudo first order kinetics (K-obs = 0.085 min(-1)). The non-hydrolytic mechanism was further supported by the hydrolysis of pNPP which followed the pseudo first order kinetics (K-obs = 1.98 x 10(-2) min(-1)) having no pH effect.