Zinc(ii) and cadmium(ii) complexes of N-terminally free peptides containing two separate cysteinyl binding sites

摘要: The hexa- and hepta-peptides CSSACS-NH2 ACSSACS-NH2 have been synthesized by solid phase peptide synthesis their zinc(II) cadmium(II) complexes studied potentiometric, NMR spectroscopic ESI MS techniques. Both peptides outstanding binding affinity but coordination chemistry is different. In the case of hexapeptide, amino terminus primary metal site in form a stable (NH2,S−) 5-membered chelate supported macrochelation via distant cysteinyl residue. heptapeptide slightly less effective binder its more versatile. thiolate groups are sites for both ions an 18-membered (S−,S−) macrochelate favored mode peptide. basic samples deprotonated group can also contribute to binding. Moreover, interaction terminal amino-N thiolate-S− Cys(2) moiety promote deprotonation ion amide between these residues. This reaction results formation (NH2,N−,S−) fused chelates Zinc(II) induced already described various histidine, this first example Cd–N(peptide amide) bond.