Bacterial nitrogen fixation

Many key protein ET processes have become accessible to theoretical analysis recently because of high-resolution x-ray stmctural data. These proteins include the bacterial photosynthetic reaction centre [18], nitrogenase (responsible for nitrogen fixation), and cytochrome c oxidase (the tenninal ET protein in mammals) [19, 20]. Although much is understood about ET in these molecular machines, considerable debate persists about details of the molecular transfonnations. 

Nevertheless, cereal plants can interact with endosymbionts, capable of nitrogen fixation in other species, and be stimulated in their productivity. The odds of soil life are balanced for some bacteria by their interactivity at rhizosphere level, and a realm of exchanged signals dictates entry into hormonally reprogrammed root sites. Specificity for partner plant species is part of a fine speciation process that actively involves the bacterial nodulation genes, and continues to drive their variation dynamics. 

Bacterial ADPGPP enzymes, 12 491 Bacterial a-amylases, 10 280 Bacterial artificial chromosome (BAC) vectors, 12 508 Bacterial cellulose, 20 557 Bacterial genera, nitrogen fixation by, 17 295-296... 

The link between nitrogen fixation and the oxidation of hydrogen in bacterial systems is schematically summarized in Scheme 8.73... 

Bacterial ferredoxins function primarily as electron carriers in ferredoxin-mediated oxidation reduction reactions. Some examples are reduction of NAD, NADP, FMN, FAD, sulfite and protons in anaerobic bacteria, CO -fixation cycles in photosynthetic bacteria, nitrogen fixation in anaerobic nitrogen fixing bacteria, and reductive carboxylation of substrates in fermentative bacteria. The roles of bacterial ferredoxins in these reactions have been summarized by Orme-Johnson (2), Buchanan and Arnon (3), and Mortenson and Nakos (31). 

N. Rigopoulos, and R. C. Fuller The pyruvate phosphoclastic reaction and light-dependent nitrogen fixation in bacterial photosynthesis. Proc. Nat. Acad. Sci. (U. S.) 52, 762-768 (1964). 

Nitrogen undergoes a complicated series of cyclic pathways in the ecosystem (Fig. 8.2). The atmospheric form of free nitrogen must be fixed —incorporated into chemical compounds (e.g., NH3) which can be utilized by plants. This nitrogen fixation can be accomplished by bacterial action of both free-living soil bacteria such as azotobacter and chlostridium and symbiotic bacteria such as rhizobium. It can also be... 

Loach, P.A. (1980) Bacterial reaction center (RC) and photoacceptor complex preparations, in San-Pietro, A. (ed) Methods in Enzymology, Vol. 69, Photosynthesis and Nitrogen Fixation, part C, Academic Press, N.Y. pp. 155-172. 

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