title: [4Fe4S]2+ clusters exhibit ground-state paramagnetism.
abstract: Two proteins involved in nitrogen fixation contain ferredoxin-type [4Fe4S] clusters that exist in paramagnetic ground state upon oxidation, a property never observed since the discovery of ferredoxins 50 years ago. This unique characteristic suggests a specific coupling in these clusters necessary for nitrogen fixation and implies an evolutionary connection between the clusters in the two proteins.
authors.affiliation: Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70808, USA.
authors.forename: Kresimir
authors.initials: K
authors.lastname: Rupnik
authors.forename: Chi Chung
authors.initials: CC
authors.lastname: Lee
authors.forename: Yilin
authors.initials: Y
authors.lastname: Hu
authors.forename: Markus W
authors.initials: MW
authors.lastname: Ribbe
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Hales
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D008983:Molybdoferredoxin / Q000737:chemistry*; D009586:Nitrogen Fixation; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry*; D055503:Protein Multimerization
chemical_list: D001426:Bacterial Proteins; D007506:Iron-Sulfur Proteins; D008983:Molybdoferredoxin; C092498:NifB protein, Bacteria; D010088:Oxidoreductases; C029130:nitrogenase reductase