The Unusual Role of Pro in Cu(II) Binding by His2-Cyclopentapeptide

In this paper, we present findings from studying the interaction of copper(II) ions with the His(2)-cyclopentapeptide and the role of proline used for the purpose of potentiometric titration and UV-Vis, CD and EPR spectroscopic measurements. Experiments of two homodetic peptides differing by one amino acid residue were conducted for a ligand to metal ratio of 1:1 in the pH range 2.5-11.0. The presented studies reveal that peptides form only mononuclear complexes, and the CuH2L complex appears in the system first (for both L1 and L2). Study results show that the presence of Pro influences the structure of formed complexes and their stabilities and has a strong impact on the efficiency of copper(II) coordination.

Automated summary

The presence of proline in the interaction between copper(II) ions and His(2)-cyclopentapeptide influences the structure and stability of the formed complexes, and has a significant impact on the efficiency of copper(II) coordination.