title: Copper(II) complexes of N-terminal protected tri- and tetra-peptides containing histidine residues.
abstract: Copper(II) complexes of peptides containing two or three histidyl residues (Ac-HisGlyHis-OH, Ac-HisGlyHis-NHMe, Ac-HisHisGlyHis-OH and Ac-HisHisGlyHis-NHMe) have been studied by potentiometric, UV-Vis, EPR and CD spectroscopic measurements. The imidazole nitrogen atoms are described as the primary metal binding sites of all ligands resulting in the formation of various macrochelates in the pH range 4 to 7. The (Nim, N-, Nim)-co-ordinated [CuH-1L]0+ complexes were mainly detected in samples containing free carboxylates at the C-termini, whilst the [CuH-2L]-(0) complexes were the predominant species in slightly alkaline solution and their binding modes were described via 4N-co-ordination (Nim, N-, N-, Nim) in (7,5,6)-membered fused chelate rings. Deprotonation and co-ordination of the third amide nitrogens were detected above pH approximately 9 in all cases.
authors.affiliation: Istituto CNR di Chimica Biomolecolare, Sezione di Sassari, trav. La Crucca 3, I-07040 Li Punti, Sassari, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Sanna
authors.forename: Giovanni
authors.initials: G
authors.lastname: Micera
authors.forename: Csilla
authors.initials: C
authors.lastname: Kallay
authors.forename: Viktoria
authors.initials: V
authors.lastname: Rigo
authors.forename: Imre
authors.initials: I
authors.lastname: Sovago
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry; D002413:Cations, Divalent; D002942:Circular Dichroism; D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D006639:Histidine / Q000737:chemistry*; D008667:Metalloproteins / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D009842:Oligopeptides / Q000737:chemistry*; D011199:Potentiometry; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet
chemical_list: D002413:Cations, Divalent; D008667:Metalloproteins; D009842:Oligopeptides; D006639:Histidine; D003300:Copper