Résumé
A new peptide design has been introduced to model the tetracysteinate zinc sites involving CXXC motifs present in beta-hairpins. It is based on a cyclic peptide incorporating one CXXC motif in addition to a variable CXC motif in a linear chain grafted onto the cycle via a glutamate or a lysine side chain. This 20-amino acid design has been used to model the Zn(Cys)4 sites of the heat shock protein Hsp33. TheZn2+ and Co2+ complexes were characterized by UV/vis, CD and NMR spectroscopy. The structures of two metallated peptides were solved by NMR. An excellent similarly was achieved between the model peptide and the target protein, both at the metal binding site and in the surrounding hydrogen bond network. Preliminary reactivity studies toward H2O2 are reported and show that the best model fit the kinetics observed for Hsp33.