Clostridium pasteurianum, nitrogen fixation

Mortenson, L.E. Nitrogen fixation in extracts of Clostridium pasteurianum. In Non-heme Iron Proteins Role in Energy Conversion,... 

McNary, J.H. and R.H. Burris. Energy requirements for nitrogen fixation by cell-free preparations from Clostridium pasteurianum. J. Bacterid. 84, 598-599 (1962). 

Ferredoxin requirement for nitrogen fixation by extracts of Clostridium pasteurianum. Biochim. Biophys. Acta 81, 473—478 (1964). 

Ferredoxin and ATP, requirements for nitrogen fixation in cell-free extracts of Clostridium pasteurianum. Proc. Natl. Acad. Sci. (U. S.) 52, 272—279 (1964b). 

Nitrogen fixation takes place in bacteria Uving in symbiosis, such as Rhizo-bium meliloti in Leguminosae, but also in free hving bacteria like Azotobacter vinelandii (aerobic soil bacteria) or Clostridium pasteurianum (anaerobic soil bacteria). In this way, at ambient temperature and pressure. Nature produces around 1.7 x 10 tonnes of ammonia per annum. [27]... 

In 1930, Hermann Bortels (1902-1979) recognised that nitrogen fixation is a molybdenum-dependent process. Obviously, the nitrogenases from Rhizobium meliloti, Azotobacter vinelandii and Clostridium pasteurianum have a similar constitution. In 1966, Leonard E. Mortenson identified for the first time an Fe- and a MoFe-protein as parts of the nitrogenase enzyme system. The exact structure of the nitrogenase-molybdenum-iron protein from Azotobacter vinelandii [28] was clarified in 1992, and that from Clostridium pasteurianum [29] in 1993, both by Douglas C. Rees. [30] The Fe-protein is a y2-dimer with a molar mass of some 60,000 Daltons, and the MoFe-protein is an ca. 

Nitrogenase.—A review of the recent chemistry of nitrogen fixation has appeared. The iron protein of nitrogenase from Clostridium pasteurianum acts as a one-electron redox system in the sequence ... 

Thiol extrusion of the FeS centres from Azobacter vinelandii and Clostridium pasteurianum with alkyl fluorothiols allows identification of at least two Fe4S4 and one FegSj cluster in the (Fe-Mo) protein. A cluster model in which two Fe4S4 units are bridged through a comer iron on each cube by a Mo S4 unit is proposed for the active site of the (Fe-Mo) cofactor. Molecular nitrogen binds axially to the central molybdenum and is Ji-bonded to the iron in the cubes. This weakens and activates the N=N bond and electrons are injected stepwise via the two iron-sulphur cubes with successive protonation at the terminal N. This latter point is consistent with a report that N—NHg is important in nitrogen fixation. 

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