Characterization of the copper(II) binding site in the pink copper binding protein CusF by electron paramagnetic resonance spectroscopy

Andrei V. Astashkin, Arnold M. Raitsimring, F. Ann Walker, Christopher Rensing, Megan M. McEvoy

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Electron paramagnetic resonance (EPR) spectroscopy has been used to structurally characterize the copper-binding site in CusF protein from Escherichia coli. The EPR spectra indicate a single type II copper center with parameters typical for nitrogen and oxygen ligands (A∼200 G, g∼2.186, g∼2.051). The pulsed EPR data show that one of the ligands to Cu2+ is an imidazole ring of a histidine residue. The remote amino nitrogen of this imidazole ring is readily observed by electron spin-echo envelope modulation spectroscopy, while the imino nitrogen that is directly coordinated to the Cu2+ ion is observed by pulsed electron-nuclear double resonance (ENDOR). In addition, the ENDOR spectra reveal the presence of one more nitrogen ligand that was assigned to be a deprotonated peptide nitrogen. Apart from the two nitrogen ligands, it has been established that there are two nearby hydroxyl protons, although whether these belong to a single equatorial water ligand or two equatorial hydroxide ligands is not known.

Original languageEnglish (US)
Pages (from-to)221-230
Number of pages10
JournalJournal of Biological Inorganic Chemistry
Volume10
Issue number3
DOIs
StatePublished - May 1 2005

Keywords

  • Copper homeostasis
  • Electron paramagnetic resonance spectroscopy

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry

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