Biochemistry of Nitrogenase

The purpose of this chapter is to summarize the attempts of my research group to mimic the chemistry of the biological fixation of nitrogen in a stable chemical system amenable to a detailed study of the chemical mechanism. The biochemistry of nitrogenase is developing rapidly and is reasonably well understood at the descriptive level, but it has not given more than a hint of the chemical mechanism (1, 2). 

Smith, B.E. (2000) Chemistry and biochemistry of nitrogenase, Curr. Plant Sci. Biotechnol Agric. 38 (Nitrogen Fixation From Molecules to Crop Productivity), 11-12. 

The enzymology and biochemistry of nitrogenases started only a few years before the first dinitrogen metal complex was discovered by Allen and Senoff in 1965. Cooperation and mutual encouragement increased when more and more results were found on both sides. Two iron-sulfur proteins are involved in the nitrogenase complex. The larger protein, the nitrogenase itself, consists of four subunits and has an... 

A more detailed review of the biochemistry of nitrogenase is not within the scope of this book. There are many reviews and books on this subject, e.g., those written by Stewart and Rowell (1986), Shilov (1987, 1992 b), Gallon and Chaplin (1988), Gresshoff et al. (1990), Burgess (1991), Smith and Eady (1992). There are also books on molybdenum enzymes (e. g., Spiro, 1985). Most reviews mentioned earlier in this section and in Section 3.3 contain short outlines of recent progress in the biochemistry of nitrogenase. 

A review of the biochemistry of nitrogenases has appeared, and structural details of the iron-molybdenum cofactor have been surveyed. ... 

Contents E. I. Solomon, K. W.Penfield, D.E. Wilcox Active Sites in Copper Proteins. An Electronic Structure Overview. -B.A.Averill Fe-S and Mo-Fe-S Clusters as Models for the Active Site of Nitrogenase. - N.D. Chasteen The Biochemistry of Vanadium. -KKustin, G.C. McLeod, T.R. Gilbert,... 

The focus of this review will be primarily on the structures of the metal centers and polypeptide chains of the nitrogenase proteins, based on crystallographic structures of both the Fe-protein and the MoFe-protein, which have been recently determined at Caltech (15-19). Structural work on the MoFe-protein is also underway in the laboratory of J. Bolin at Purdue (19a). To minimize overlap with the existing, excellent reviews on the chemistry, biochemistry, biophysics, and genetics of nitrogenase and related chemical systems (2-8), these topics will be primarily discussed in the context of the nitrogenase protein structures. 

Seefeldt L. C., Rasche M. E., and Ensign S. A. (1995) Carbonyl sulfide and carbon dioxide as new substrates, and carbon disulfide as a new inhibitor, of nitrogenase. Biochemistry 34, 5382-5389. 

Garcia-Horsman JA, Berry E, Shapleigh JP, Alben JO, Gennis RB (1994) A novel cytochrome c oxidase from Rhodobacter sphaeroides that lacks Cua. Biochemistry 33 3113-3119 Georgiadis MM, Komiya H, Chakrabarti P, Woo D, Komuc JJ, Rees DC (1992) Crystallographic structure of nitrogenase iron protein from Azotobacter vinelandii. Science 257 1653-1659... 

There are several other references on the chemistry of nitrogen reduction in model complexes and on the biochemistry with nitrogenases. 

We will summarize the status of the biochemistry of N2 fixation, including nitrogenase (N2ase) reactions and characteristics, with exten-... 

See I. Dance (2006) Biochemistry, vol. 45, p. 6328 - Mechanistic significance of the preparatory migration of hydrogen atoms around the FeMo-coactive site of nitrogenase . 

G Lihong, M. Madden,VK. Shah, RH. Burris (1990) Citrate substitutes for homocitrate in nitrogenase of a nifV mutant of Klebsiella pneumoniae. Biochemistry, 29 8577-8581... 

Strop P,Tatahara PM, Chiu H-J, Angove HC. Crystal structure of the all-ferrous [4Fe-4S]° form of the nitrogenase iron protein from Azotobacter vinelandii. Biochemistry 2001 40 651-6. 

Chan, J.M., Wu, W., Dean, D.R., and Seefeldt, L.C. (2000) Construction and Characterization of a heterodimeric iron protein defining rolee for adenosin triphosphate in nitrogenase catalysis, Biochemistry 39, 7221-7228. 

Chiu, H-J, Peters, J. W., Lanzillota, W N., Ryle, M. J., Seefeldt, L. C., Howard, J.B., and Rees, D. C. (2001) MgATP-bound and nucleotide-free structure of a nitrogenase protein complex between the 127 D-Fe-protein and the MoFe-protein, Biochemistry 40, 641-650. 

DeRose, V.J. C.-H., Kim, W.E., Newton, D. R.D., and Hoffman B. M. (1995) Electron Spin Echo Modulation Spectroscopic Analysis of Altered Nitrogenase MoFe Proteins of Azotobacter vinelandii, Biochemistry 34, 2809-2814... 

Duyvis, M. G., Wassink, H., and Haaker, H. (1998) Nitrogenase of Azotobacter vinelandii kinetic analysis of the Fe protein cycle, Biochemistry 37, 17345-17354. 

Lanzilotta, W.N and Seefeldt, L.C. (1997) Changes in the midpoint potential of the nitrogenase metal centers as a result of iron protein-molybdenum-iron protein complex formation, Biochemistry 36, 12976-12983. 

Siemann, S., Schneider, K., Drottboom, M., and Muller, A. (2002) The Fe-only nitrogenase and the Mo nitrogenase from Rhodobacter capsulatus. A comparative study on the redox properties of the metal clusters present in the dinitrogenase components, European Journal of Biochemistry 269, 1650-1661. 

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