title: The unusual stabilization of the Ni2+ and Cu2+ complexes with NSFRY.
abstract: The binding mode provided by an unprotected peptide with non-coordinating side-chains is simple and well understood. However, when particular residues are inserted into the peptide sequence, they can have a significant impact on the stability of the formed complexes. The presence of non-bonding side chains of amino acids close to the metal binding centre in the peptide/protein can provide special interactions which result in increasing the stabilization of the formed species. Moreover, these interactions can play a crucial role in generating particular protein structures and in influencing biological activity. In the present paper it is shown how peptides with no specific predisposition for metal binding, like ANF peptides, can form metal complexes with a very high thermodynamic stability. For better understanding this peculiar behavior, a combined pH-metric and spectroscopic method was used to determine the stability and the solution structure of Cu(2+) and Ni(2+) complexes with NSFRY-NH(2) (ANF peptide) and a series of analogue peptides. All obtained data support the hypothesis that the complex-formation process is very similar for both metal ions and all the ligands, involving some intramolecular interactions among the different side chains. The two-dimensional NMR analysis of nickel complexes showed the occurrence of many inter-residue correlations and suggested the presence of a direct interaction between the d electrons of the metal ion and the π-ring system of the aromatic side-chains of the ligand.
authors.affiliation: Department of Inorganic Chemistry, Medical University of Wroclaw, Szewska 38, 50-139 Wroclaw, Poland. anna.janicka-kloss@am.wroc.pl
authors.forename: Anna
authors.initials: A
authors.lastname: Janicka-Klos
authors.forename: Elena
authors.initials: E
authors.lastname: Porciatti
authors.forename: Daniela
authors.initials: D
authors.lastname: Valensin
authors.forename: Chiara
authors.initials: C
authors.lastname: Conato
authors.forename: Maurizio
authors.initials: M
authors.lastname: Remelli
authors.forename: Stanislaw
authors.initials: S
authors.lastname: Oldziej
authors.forename: Gianni
authors.initials: G
authors.lastname: Valensin
authors.forename: Henryk
authors.initials: H
authors.lastname: Kozlowski
mesh_terms: D000595:Amino Acid Sequence; D009320:Atrial Natriuretic Factor / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry*; D011522:Protons
chemical_list: D009942:Organometallic Compounds; D010446:Peptide Fragments; D011522:Protons; D003300:Copper; D009532:Nickel; D009320:Atrial Natriuretic Factor