Complexation of copper(II) with a macrocyclic peptide containing histidyl residues: novel observation of NMR spectra of paramagnetic copper(II) compounds

The copper(II) binding properties of the cyclic peptide c(HGHK)

“…In any case, the CuH À4 L species is still a minor complex at pH 11 and probably plays a negligible role in metal ion-peptide equilibria. A similar coordination manner of Cu(II) ion was previously reported for the Cu(II)-c(GHGHGHG) system at high pH [13]. Indeed, this ligand was reported to form only two types of complexes.…”

The cyclopeptides with the multi-His motif as ligands for copper(II)

“…Earlier studies on the coordination abilities of cyclopeptides towards Cu(II) ions have shown that cyclopeptides with histidyl residue in the peptide sequence are able to bind metal ions via side chain imidazole and deprotonated amide nitrogens from main peptide chain [11][12][13][14][15][16]. The structural modification of the cyclopeptides e.g.…”

Impact of ring size on the copper(II) coordination abilities of cyclic tetrapeptides

“…The previous studies on the binding abilities of cyclopeptides towards Cu(II) ions [5][6][7][8][9][10][11] showed that His-containing cyclopeptides are able to bind copper(II) tightly through imidazole as well as amide nitrogens. The pH and the peptide ring size have a great impact on the kind of the coordinated nitrogens.…”

“…Insertion of one more carbon atom into the peptide cycle causes that the oxidation of the copper is observed [10]. For the peptides with greater than 13-membered rings the formation of the complex with the {4 Â N À } binding mode is preferred [8,9,11].…”