title: Cu2+ and Ni2+ interactions with N-terminal fragments of Hpn and Hpn-like proteins from Helicobacter pylori: unusual impact of poly-Gln sequence on the complex stability.
abstract: The N-terminal protected and unprotected peptides MAHHEEQHG-NH(2), Ac-MAHHEEQHG-NH(2) from Hpn (Helicobacter histidine-rich protein) and MAHHEQQQQQQA-NH(2), Ac-MAHHEQQQQQQA-NH(2) from Hpn-like protein, respectively, were synthesized and their interactions with Cu(2+) and Ni(2+) ions were studied by potentiometric, UV-visible, CD, and EPR techniques. The studies have shown that because of their albumin-like sequence, unprotected peptides are very effective chelating agents for both studied metals. The presence of the hexa-glutamine sequence has very distinct impact on the stability of the complexes formed even if direct interactions with metal ions were not found. The much more effective Ni(2+) binding by Hpn-like N-terminal domain when compared to Hpn protein could be critical for different biological functions played by both proteins.
authors.affiliation: Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie, 14, 50383 Wroclaw, Poland.
authors.forename: Danuta
authors.initials: D
authors.lastname: Witkowska
authors.forename: Sylwia
authors.initials: S
authors.lastname: Bielinska
authors.forename: Wojciech
authors.initials: W
authors.lastname: Kamysz
authors.forename: Henryk
authors.initials: H
authors.lastname: Kozlowski
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D002614:Chelating Agents; D056831:Coordination Complexes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D016480:Helicobacter pylori; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009532:Nickel / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D011199:Potentiometry; D011485:Protein Binding
chemical_list: D001426:Bacterial Proteins; D002614:Chelating Agents; D056831:Coordination Complexes; D010455:Peptides; C097188:polyglutamine; C022838:nickel chloride; D003300:Copper; D009532:Nickel; C029892:cupric chloride