title: De novo design and spectroscopic characterization of a dinucleating copper-binding pentadecapeptide.
abstract: A spectroscopic study of aqueous solutions of Ac-WGHGHGHGPGHGHGH-NH(2) (HGP) indicates that copper(II) binds to the peptide to form a 2:1 Cu(2+)/HGP complex with four nitrogen atoms in the copper coordination environment. Electron paramagnetic resonance (EPR) and UV-visible data suggest copper binding through the peptide backbone and imidazole nitrogen donors. Circular dichroism data show that HGP is unbound below pH 5.5 and is copper-saturated at pH 9 and above. The apo form of the peptide is unstructured in solution and is organized into a turn conformation in the presence of 2 mol equiv of Cu(2+) at basic pH. EPR measurements for 2:1 Cu(2+)/HGP solutions in the g = 2 region and within the pH range 7-11 exhibit axial spectra. A molecular-mechanics-minimized model of the Cu(2+)/HGP complex gave a Cu...Cu separation of 8 A.
authors.affiliation: Department of Chemistry, Texas A&M University, College Station, TX 77842-3012, USA. david.rockcliffe@kysu.edu
authors.forename: David A
authors.initials: DA
authors.lastname: Rockcliffe
authors.forename: Arthur
authors.initials: A
authors.lastname: Cammers
authors.forename: Ayaluru
authors.initials: A
authors.lastname: Murali
authors.forename: William K
authors.initials: WK
authors.lastname: Russell
authors.forename: Victoria J
authors.initials: VJ
authors.lastname: DeRose
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D008969:Molecular Sequence Data; D009942:Organometallic Compounds / Q000737:chemistry*; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013329:Structure-Activity Relationship
chemical_list: D009942:Organometallic Compounds; D010455:Peptides; C511458:acetyl-tryptophyl-(glycyl-histidyl)3-glycyl-prolyl-(glycyl-histidyl)3-amide; D003300:Copper