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Fritz Haber 1868 - 1934

Fritz Haber 1868 - 1934. 1918 Nobel prize “synthesized ammonia from its elements”. Annual Global N-fixation. Data from various sources, compiled by DF Bezdicek & AC Kennedy, in Microorganisms in Action (eds. JM Lynch & JE Hobbie). Blackwell Scientific 1998. Do not include taxa that fix N 2.

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Fritz Haber 1868 - 1934

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  1. Fritz Haber 1868 - 1934 • 1918 Nobel prize “synthesized ammonia from its elements”

  2. Annual Global N-fixation Data from various sources, compiled by DF Bezdicek & AC Kennedy, in Microorganisms in Action (eds. JM Lynch & JE Hobbie). Blackwell Scientific 1998.

  3. Do not include taxa that fix N2 Include taxa that fix N2 Raymond et al 2004 Mol. Biol. Evol. 21:541-554 Possess homologs to NifH and Nif D but not known to fix N2

  4. Nitrogenase enzyme complex

  5. Nitrogenase enzyme complex MoFe protein • Dinitrogenase • Tetramer of two different dimers 2 2 heterodimer •  = NifD,  = NifK • Contains • Two MoFeS centers (active site for N2 reduction) • Four Fe4S4 centers • Combines N2 and H+ to reduce N2 to NH3

  6. Nitrogenase enzyme complex NH3 MoFe protein N2 Fe protein Fe protein e- 65 Å 190 Å From: Catalina Achimhttp://www.chem.cmu.edu/groups/achim/research/magneto.html

  7. Nitrogenase enzyme complex Fe protein • Dinitrogenase reductase • Dimer of two identical subunits 2 dimer •  = NifH • Contains single Fe4S4 center • Accepts reducing power (electrons) and reduces MoFe protein (dinitrogenase)

  8. Nitrogenase enzyme complex NH3 MoFe protein N2 Fe protein Fe protein e- 65 Å 190 Å From: Catalina Achimhttp://www.chem.cmu.edu/groups/achim/research/magneto.html

  9. Versatility of nitrogenase complex

  10. Vesicles are the site of N2-fixation in Frankia. Nitrogenase reduces nitrogen using electrons and ATP from compounds donated by the plant (succinate is only one possibility). The product ammonia is most likely excreted from the vesicle where plant enzymes (GS) convert it to organic nitrogen (glutamine). (D. Benson)

  11. Nitrogenase enzyme complex 2 ATP Ferredoxinoxidized Fered. MoFeox. 2 NH3,H2 e- e- e- e- e- e- Ferredoxinreduced Feox. MoFered. N2, 8H+ 2 ADP 2 Pi

  12. Nitrogenase enzyme complex NH3 MoFe protein N2 Fe protein Fe protein e- 65 Å 190 Å From: Catalina Achimhttp://www.chem.cmu.edu/groups/achim/research/magneto.html

  13. Tree of NifH and NifD homologs Groups I - IIIpossess functional nitrogenases Raymond et al 2004 Mol. Biol. Evol. 21:541-554

  14. Two proposednif gene vs. spp. trees (b) Methanogen origin hypothesis (a) Last common ancestor (LCA) hypothesis

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