Information AboutNitrogenase |
| CATEGORIES ABOUT NITROGENASE | |
| ec 1.18.6 | |
| iron-sulfur proteins | |
| nitrogen metabolism | |
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All nitrogenases have an iron- and sulfur-containing cofactor that includes a metal atom assumed to be the active site. In most, this is Molybdenum , though in some species it is replaced by Vanadium or Iron . Due to the similarity between Oxygen and nitrogen gas, most nitrogenases are irreversibly inhibited by Dioxygen '' In Vitro ''. This requires mechanisms for nitrogen fixers to avoid oxygen '' In Vivo ''. Despite this problem, many use oxygen as a terminal electron acceptor for respiration. One known exception, a recently-discovered nitrogenase of Streptomyces thermoautotrophicus, is unaffected by the presence of oxygen. The Azotobacteraceae are unique in their ability to employ an oxygen-labile Nitrogenase under aerobic conditions. This ability has been attributed to a high metabolic rate allowing oxygen reduction at the membrane, but this idea has been shown to be unfounded and impossible at oxygen concentrations above 70 uM (ambient concentration is 230uM O2), as well as during additional nutrient limitationsOelze J. 2000. Respiratory protection of nitrogenase in Azotobacter species: Is a widely-held hypothesis unequivocally supported by experimental evidence? ''FEMS Microbiol Rev''. 24(4):321-33.. The reaction that this enzyme performs is: : N2 + 8H+ + 8e- + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi ORGANISMS THAT SYNTHESISE NITROGENASE SEE ALSO REFERENCES |
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