Nitrogen fixation enzymatic

Hoffman BM, Dean DR, Seefeldt LC. Climbing nitrogenase toward a mechanism of enzymatic nitrogen fixation. Acc Chem Res. 2009 42 609-19. 

Dieter Otto Sellmann Iron-diazene complex as model for enzymatic nitrogen fixation... 

The reactions of dinitrogen in its mononuclear complexes (J. Chatt, J. Organometallic Chem., 1975. 100, 17). Non-enzymatic simulation of nitrogenase reactions and the mechanism of biological nitrogen fixation (G. N. Schrauzer, Anyew. Chem. Internal. Edn.. 1975. 14. 514). 

Schematic Diagram of the Nitrogenase Complex Illustrating the Flow of Electrons and Energy in Enzymatic Nitrogen Fixation.

Investigations on model systems have been conducted for all these processes. There is no doubt that results from such models will one day form a good basis for understanding the mechanism of enzymatic nitrogen fixation. 

This paper demonstrates the development and use of models in two areas of bioinorganic chemistry, the mechanism of biological nitrogen fixation and the enzymatic function of vitamin B12 coenzymes. 

Nitrogen fixation is the process by which nitrogen present in the atmosphere as N2 is enzymatically converted to NH3 by some bacteria and blue-green algae. This process is crucial to all other organisms because they can use only NH4", and not N2, as the source of nitrogen for biosynthesis. 

Iron and sulfur can be extracted from F. the resulting apoferredoxin is reactivated by iron(II) salts and sulfides. The synthesis of the iron-free protein has been achieved by the Merrifield technique. On account of their properties as redox systems (Fe +e" Fe ") the F. effect electron transport between enzyme systems but do not exhibit any enzymatic activity. They transport electrons in the respiratory chain, in photosynthesis, and in nitrogen fixation. The iron-sulfur protein P439 of the Fc4S4-type (Mr 11600) plays a role in photosynthesis. Conclusions can be drawn about the evolutionary histories of plants from the similarities and differences in the amino acid sequences. For the evolutionary history of F. in photosynthesis, see Lit.K F. with FejSj- and FejSg-clusters also occur in bacteria Lit. TrendsBiochem.Sci. 13,30-33(1988). FEMSMicrobiol. Rev. 54,155-176 (1988) Trends Biochem. Sci. 13,369 f. (1988). 

The nitrogenase enzymes are the sole mediators of biological nitrogen fixation, the microbial reduction of dinitrogen to ammonia. The enzymatic conversion entails the intervention of a set of biometalloclusters with distinctive, often unique, properties. The enzyme system is complex and particularly resistant to biochemical and biophysical analysis at the molecular level, and the clusters themselves have very limited synthetic precedent in form and reactivity. As a result, a comprehensive chemical understanding of the nitrogenase clusters remains elusive despite decades of study. 

Figure 1 The FixL/FixJ two-component regulatory system. In two-component regulatory systems, the inputs and outputs are variable, but the transmitter and receiver domains from unrelated systems share 20% identity. The input of the sensor FixL is a heme-binding domain that inhibits phosphorylation when O2 binds and that permits enzymatic activity when O2 leaves. The output response is transcriptional activation at nitrogen fixation promoters for only hyrpoxic conditions. (From Ref. 36.)...

Fig. 9.15 Prof. Dr. chem. Victor Andreyevich Yakovlev (1915-1977). Graduated from the Academy of Chemical Protection (1940) and worked in lahoratories of chemical plant protection. Fields of research kinetics of enzymatic reactions, electronic mechanism of enzymatic nitrogen fixation, etc. (monographs [160, 161]). Organizer and head of the Laboratory of Kinetics of Enzymatic Catalysis, Institute of Chemical Physics, USSR AS (1962-1967), director of VNfVI, and head of the biochemical laboratory (1967-1977). He ensured the organization of scientific and technological research, including electrosynthesis, in VNIVI and established creative climate. Photo in his office in VNlVl, January 1970...

The biological reaction that counterbalances the loss of nitrogen from soils or agroecosystems is biological nitrogen fixation (BNF), which is the enzymatic reductimi of the atmospheric dinitrogen (N2) to ammonia, catalyzed by the nitrogenase... 

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