Iron-Only Nitrogenase: Exceptional Catalytic, Structural and Spectroscopic Features

  • K. Schneider
  • A. Müller
Part of the Nitrogen Fixation: Origins, Applications, and Research Progress book series (NITR, volume 1)


The classical, molybdenum-containing nitrogenase system exists in all diazotrophic microorganisms that have been examined. It was a long-held dogma that Mo is absolutely necessary for nitrogen fixation, however, in 1980, Bishop and coworkers discovered that Azotobacter vinelandii Nif͞ point mutants, which are defective in Mo-nitrogenase synthesis, were able to fix N2 in the absence of molybdenum (Bishop et al., 1980). In 1986, the first Mo-independent “alternative” nitrogenases were isolated from two Azotobacter species, A. vinelandii (Hales et al., 1986) and A. chroococcum (Robson et al., 1986) and both identified as vanadium-containing nitrogenases (V-nitrogenases). It came as an even a greater surprise when, two years later, a second type of alternative nitrogenase, lacking both Mo and V, was isolated from A. vinelandii as well (Chisnell et al., 1988). This last enzyme system has now also been isolated from phototrophic bacteria, e.g., Rhodobacter capsulatus (from a ni/HDK͞ strain) (Schneider et al., 1991) and Rhodospirillum rubrum (from a nifH͞ strain) (Davis et al., 1996). Based on multielement analyses by ICP-MS, the Mo/V-independent nitrogenase from R. capsulatus has been unambiguously identified as an enzyme system that contains only iron but no heterometal atoms (Müller et al., 1993; Schneider et al., 1997); a fact that has led to their designation as either ‘Fe nitrogenase’ or ‘Fe-only nitrogenase’.


Rhodospirillum Rubrum Rhodobacter Capsulatus MoFe Protein Azotobacter Chroococcum Methanosarcina Barkeri 
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Copyright information

© Springer Science+Business Media Dordrecht 2004

Authors and Affiliations

  • K. Schneider
    • 1
  • A. Müller
    • 1
  1. 1.Fakultät für Chemie, Lehrstuhl für Anorganische Chemie IUniversität BielefeldBielefeldGermany

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