The Analysis of the Structural Aspects of Cu(II) Binding by Cyclic His/Asp-Analogues of Somatostatin

Two new somatostatin analogs with a characteristic part of the sequence in their structures, -c(Cys-Phe-Trp-Lys-Thr-Cys)-, were synthesized and analyzed in terms of their coordination abilities with copper(II) ions. Cyclic peptides analyzed in our previous work had histidine and aspartic acid moieties in their structures which were responsible for metal ion coordination. In analyzed molecules these amino acids are also present. Peptides Ac[D1,2,9,10]c(SST) and Ac[H1,2,9,10]c(SST) have four aspartic acid or four histidine moieties, respectively. Both peptides bind Cu(II) effectively. Due to similar structures and the possibility of comparing the obtained results with these for the two previously published, the coordination abilities of two new ligands are possible to propose. Moreover, the effectiveness of copper(II) ion binding by four cyclic His/Asp-analogues of somatostatin is also discussed here. The peptide with four histidine moieties is the most efficient among described ligands.