title: Copper-peptide complex structure and reactivity when found in conserved His-X(aa)-His sequences.
abstract: Oxygen-activating copper proteins may possess His-X(aa)-His chelating sequences at their active sites and additionally exhibit imidiazole group δN vs εN tautomeric preferences. As shown here, such variations strongly affect copper ion's coordination geometry, redox behavior, and oxidative reactivity. Copper(I) complexes bound to either δ-HGH or ε-HGH tripeptides were synthesized and characterized. Structural investigations using X-ray absorption spectroscopy, density functional theory calculations, and solution conductivity measurements reveal that δ-HGH forms the Cu(I) dimer complex [{Cu(I)(δ-HGH)}2](2+) (1) while ε-HGH binds Cu(I) to give the monomeric complex [Cu(I)(ε-HGH)](+) (2). Only 2 exhibits any reactivity, forming a strong CO adduct, [Cu(I)(ε-HGH)(CO)](+), with properties closely matching those of the copper monooxygenase PHM. Also, 2 is reactive toward O2 or H2O2, giving a new type of O2-adduct or Cu(II)-OOH complex, respectively.
authors.affiliation: Department of Chemistry, The Johns Hopkins University , Baltimore, Maryland 21218, United States.
authors.forename: Ga Young
authors.initials: GY
authors.lastname: Park
authors.forename: Jung Yoon
authors.initials: JY
authors.lastname: Lee
authors.forename: Richard A
authors.initials: RA
authors.lastname: Himes
authors.forename: Gnana S
authors.initials: GS
authors.lastname: Thomas
authors.forename: Ninian J
authors.initials: NJ
authors.lastname: Blackburn
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Karlin
mesh_terms: D003300:Copper / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry*; D015394:Molecular Structure; D009842:Oligopeptides / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D009842:Oligopeptides; D009942:Organometallic Compounds; D006639:Histidine; D003300:Copper; D010100:Oxygen