title: Binary and ternary mixed metal complexes of terminally free peptides containing two different histidyl binding sites.
abstract: Copper(II), nickel(II) and zinc(II) complexes of the terminally free peptides AHAAAHG and AAHAAAHG have been studied by combined applications of potentiometric and various spectroscopic techniques, including UV-visible, CD and EPR for copper(II) and UV-visible, CD and NMR for nickel(II). It was found that the octapeptide AAHAAAHG can easily bind two equivalents of copper(II) or nickel(II) ions and the amino terminus was identified as the primary ligating site of the molecule. On the other hand, this peptide has a relatively low zinc(II) binding affinity. Mono- and di-nuclear copper(II) and nickel(II) complexes were also formed with the heptapeptide AHAAAHG but this peptide can effectively bind one equivalent of zinc(II) ions, too, with the involvement of the deprotonated amide nitrogen in zinc(II) binding. The enhanced stability of the [MH-1L] species of AHAAAHG was explained by the tridentate (NH2,N(-),Nim) coordination of the amino terminus supported by the macrochelation of the internal histidyl residue. Mixed metal copper(II)-nickel(II) complexes were also formed with both peptides and copper(II) ions were coordinated to the amino terminal, while nickel(II) ions to the internal histidyl sites.
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Debrecen, H-4010 Debrecen, Hungary.
authors.forename: Agnes
authors.initials: A
authors.lastname: Grenács
authors.forename: Anikó
authors.initials: A
authors.lastname: Kaluha
authors.forename: Csilla
authors.initials: C
authors.lastname: Kállay
authors.forename: Viktória
authors.initials: V
authors.lastname: Jószai
authors.forename: Daniele
authors.initials: D
authors.lastname: Sanna
authors.forename: Imre
authors.initials: I
authors.lastname: Sóvágó
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D056831:Coordination Complexes / Q000737:chemistry* / Q000378:metabolism; D003300:Copper / Q000737:chemistry / Q000378:metabolism; D006639:Histidine / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals / Q000737:chemistry* / Q000378:metabolism; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry / Q000378:metabolism; D009842:Oligopeptides / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D055550:Protein Stability; D013053:Spectrophotometry; D015032:Zinc / Q000737:chemistry / Q000378:metabolism
chemical_list: D056831:Coordination Complexes; D008670:Metals; D009842:Oligopeptides; D006639:Histidine; D003300:Copper; D009532:Nickel; D015032:Zinc
keywords: Copper(II); Histidine; Nickel(II); Peptides; Stability constants; Zinc(II)