title: Generation of high-spin iron(I) in a protein environment using cryoreduction.
abstract: High-spin Fe(1+) sites are potentially important in iron-sulfur proteins but are rare in synthetic compounds and unknown in metalloproteins. Here, we demonstrate a spectroscopically characterized example of high-spin non-heme Fe(1+) in a protein environment. Cryoreduction of Fe(2+)-substituted azurin at 77 K with (60)Co γ radiation generates a new species with a S = (3)/2 (high-spin) Fe(1+) center having D > 0 and E/D ~ 0.25. This transient species is stable in a glycerol-water glass only up to ~170 K. A combination of electron paramagnetic resonance and Mössbauer spectroscopies provides a powerful means of identifying a transient high-spin Fe(1+) site in a protein scaffold.
authors.affiliation: Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Roman M
authors.initials: RM
authors.lastname: Davydov
authors.forename: Matthew P
authors.initials: MP
authors.lastname: McLaughlin
authors.forename: Eckhard
authors.initials: E
authors.lastname: Bill
authors.forename: Brian M
authors.initials: BM
authors.lastname: Hoffman
authors.forename: Patrick L
authors.initials: PL
authors.lastname: Holland
mesh_terms: D001400:Azurin / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D002412:Cations / Q000032:analysis; D005990:Glycerol / Q000737:chemistry; D007501:Iron / Q000032:analysis*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011550:Pseudomonas aeruginosa / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D002412:Cations; D014867:Water; D001400:Azurin; D007501:Iron; D005990:Glycerol