title: Reevaluation of copper(I) affinity for amyloid-β peptides by competition with ferrozine--an unusual copper(I) indicator.
abstract: The association constant of ferrozine (5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine-4,4''-disulfonic acid) with Cu(I) to form the chromophoric [Cu(I)(Fz)(2)](3-) complex was determined by UV/Vis titration experiments in Hepes buffer (0.1 M, pH 7.4). An association constant close to 10(12) M(-2), which is significantly weaker than those of the well-known, water-soluble, Cu(I) chelators bicinchoninic acid and 2,9-dimethyl-4,7-diphenyl-1,10-phenantroline disulfonic acid, was found. The [Cu(I)(Fz)(2)](3-) chromophore was used in UV/Vis competition experiments to determine Cu(I) binding affinity for the amyloid-β peptide involved in Alzheimer's disease and for a series of pertinent mutants. An association constant of approximately 10(7) M(-1) was found; this is much weaker than that reported for dithiothreitol and confirms that imidazoles are harder ligands than thiolates. Each His mutation (H6A, H13A, and H14A) impacts the peptide affinity for Cu(I). The native human amyloid-β peptide was found to be a fourfold-stronger Cu(I) ligand than the murine peptide, which differs by three point mutations (R5G, Y10F, and H13R) from the human one.
authors.affiliation: CNRS, Laboratoire de Chimie de Coordination, 205, route de Narbonne, 31077 Toulouse, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Alies
authors.forename: Bertrand
authors.initials: B
authors.lastname: Badei
authors.forename: Peter
authors.initials: P
authors.lastname: Faller
authors.forename: Christelle
authors.initials: C
authors.lastname: Hureau
mesh_terms: D016229:Amyloid beta-Peptides / Q000737:chemistry*; D001667:Binding, Competitive; D003300:Copper / Q000737:chemistry*; D005297:Ferrozine / Q000737:chemistry*; D006801:Humans; D007202:Indicators and Reagents / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure
chemical_list: D016229:Amyloid beta-Peptides; D007202:Indicators and Reagents; D005297:Ferrozine; D003300:Copper