Nitrogen fixation leghemoglobin

The decrease in leghemoglobin, an indicator of nitrogen fixation capacity (22) suggested the nitrogen fixation would also be... 

Terms in bold are defined in the nitrogen cycle 834 nitrogen fixation 834 symbionts 834 nitrogenase complex 835 leghemoglobin 836 glutamine synthetase 838 glutamate synthase 838 glutamine amidotransferases 840 5-phosphoribosyl-l-... 

Nitrogen fixation is the conversion of N2 gas into ammonia, a process carried out by some soil bacteria, cyanobacteria and the symbiotic bacteria Rhizobium that invade the root nodules of leguminous plants. This process is carried out by the nitrogenase complex, which consists of a reductase and an iron-molybdenum-containing nitrogenase. At least 16 ATP molecules are hydrolyzed to form two molecules of ammonia. Leghemoglobin is used to protect the nitrogenase in the Rhizobium from inactivation by 02. 

El I folk, Ada Chem. Scand. 17, S343 (1963). Resolved into four components on DEAE-cellulose column ElFfolk, ibid. 14, 609 (1960). Suggested to act as an oxido-reduction catalyst in the symbiotic nitrogen fixation idem, ibid. 15, 975 (1961). Primary structure of soybean leghemoglobin Ell-folk, Sievers, ibid. 25, 3532 (1971). 

Reducing nitrogen (as occurs in nitrogen fixation), requires energy and electrons with low-potential (electron carriers with very low EO ). The enzymes involved are very sensitive to oxygen and must be studied only under anaerobic conditions. In root nodules of plants, the anaerobic environment is provided by the protein leghemoglobin, which binds any 02 that makes its way into the nodules. 

The role of AA in nitrogen fixation, nodulation and leghemoglobin of cowpea, lucerne and groundnut (Bharti et al, 1978 Garg, 1978 Goswami and Garg, 1978 Lai et al. ... 

Fig. 9. Proposed model for the cellular compartmentalization of the reactions of nitrogen fixation, ammonium assimilation, purine synthesis, and ureide biogenesis in infected and uninfected cells of soybean root nodules. Uncertainty still exists with respect to the nature of the intermediate (e.g., IMP, XMP, xanthine, glutamine ) transported from the infected cell to the uninfected cell as well as the site of purine synthesis. In addition, as discussed in the text the site(s) of PRPP synthesis (plastid and/or cytosolic) and the path and site of synthesis (de novo from the PPP or via salvage) of tibose S-phosphate (R-S-P) are s not defined, lliese uncertainties are indicated with question marks and/or dashed lines. Lb, leghemoglobin.

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