The enzymes involved in nitrogen assimilation are:
(i) glutamate dehydrogenase (GDH),
(ii) glutamate synthase (GOGAT)
(iii) glutamine synthase (GS) and
(iv) transaminase.
The pathways of glutamate and glutamine synthesis depend upon the concentration of NH3 in the cell. At high NH3concentration,the synthesis of these two compounds takes place by two sequential reactions catalyzed by GDH and GS.
GDH is not in the major pathway of glutamate metabolism. The affinity of GDH for NH3 is relatively low. The enzyme does not function effectively at low NH3, Concentrations. Under these conditions the induction of GOGAT takes place and this enzyme catalysis the reaction. The major route of NH3 assimilation becomes the GS reaction.
Glutamate can be produced by a variety of reactions in enteric bacteria. There are three main classes of reactions according to the immediate origin of N and C atoms.
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