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In enzymology, a glutamate synthase (NADH) (EC 1.4.1.14) is an enzyme that catalyzes the chemical reaction

2 L-glutamate + NAD ${\displaystyle \rightleftharpoons }$ L-glutamine + 2-oxoglutarate + NADH + H

Glutamate synthase facilitates the ammonium assimilation pathway, which follows the enzymes, nitrite reductase and glutamine synthase. An ammonium produced by the nitrite reductase reaction will be incorporated into carbon skeleton backbone by glutamine synthase. Glutamine will be produced because of the introduction of ammonium in the carbon backbone, which can be converted into glutamate by glutamate synthase of another pathway.

These processes are common in plant roots due to the fact that if the nitrogen deficient conditions exist (with access to ammonium and nitrate ions), there will be a first priority of ammonium uptake. Thus, the two substrates of this enzyme are L-glutamate and NAD, whereas its 4 products are L-glutamine, 2-oxoglutarate, NADH, and H.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH₂ group of donors with NAD or NADP as acceptor. This enzyme participates in glutamate metabolism and nitrogen assimilation. It employs one cofactor, FMN.

Nomenclature

The systematic name of this enzyme class is L-glutamate:NAD oxidoreductase (transaminating). Other names in common use include:

• glutamate (reduced nicotinamide adenine dinucleotide) synthase,
• glutamate synthase (NADH),
• L-glutamate synthetase(NADH),
• NADH-dependent glutamate synthase,
• NADH-glutamate synthase, and
• NADH-Glutamine oxoglutarate aminotransferase (NADH-GOGAT).

See also

• Glutamate synthase (ferredoxin)
• Glutamate synthase (NADPH)

References

1. ^ Konishi, Noriyuki (27 February 2014). "NADH‐dependent glutamate synthase plays a crucial role in assimilating ammonium in the Arabidopsis root". Physiologia Plantarum. 152 (1): 138–151. doi:10.1111/ppl.12177. PMID 24576214.
2. ^ Martinez-Espinosa, R.M. (30 November 2013). "Ferredoxin-dependent glutamate synthase: involvement in ammonium assimilation in Haloferax mediterranei". Extremophiles. 18 (1): 147–159. doi:10.1007/s00792-013-0606-9. PMID 24292444. S2CID 8300669.

• Boland MJ, Benny AG (1977). "Enzymes of nitrogen metabolism in legume nodules. Purification and properties of NADH-dependent glutamate synthase from lupin nodules". Eur. J. Biochem. 79 (2): 355–62. doi:10.1111/j.1432-1033.1977.tb11816.x. PMID 21790.

• Biology

• EC 1.4.1
• NADH-dependent enzymes
• Flavoproteins
• Enzymes of unknown structure