Glutamate dehydrogenase bacteria

Other bacteria such as E. coli assimilate ammonia by incorporating it directly into a-oxoglutarate in a reaction catalysed by glutamate dehydrogenase (GDH). This reaction can be written as... 

Kjellberg S, M Hermansson, P Marden, GW Jones (1987) The transient phase between growth and nongrowth of heterotrophic bacteria with emphasis on the marine environment. Annu Rev Microbiol 41 25-49. Klump H, J Di Ruggiero, M Kessel, J-B Park, MWW Adams, FT Robb (1992) Glutamate dehydrogenase from the hyperthermophile Pyrococcus furiosus. Thermal denaturation and activation. J Biol Chem 267 22681-22685. 

While reductive animation of glutamate via glutamate synthase appears to be the major pathway for incorporation of nitrogen into amino groups, some direct animation of pyruvate and other 2-oxoacids in reactions analogous to that of glutamate dehydrogenase occurs in bacteria.105 106 Another bacterial enzyme catalyzes reversible addition of ammonia to fumarate to form aspartate (p. 685). 

In plants, molds and bacteria, A. a. into the amino group of glutamate is also possible by NADPH-de-pendent glutamate dehydrogenase (EC 1.4.1.3) the enzyme is most effective when ammonium salts are available directly from the environment in relatively... 

Glutamic dehydrogenase has been detected in bacteria, yeast, plants, and animal tissues. The enzyme has been purified extensively only from liver, and the properties of the ezyme from other sources are not known very precisely. It has been reported that glutamic dehydrogenase of plants requires DPN, while the enzyme of yeast and E. coli requires TPN. The mammalian enzyme uses both coenzymes. 

As we have just seen, L-glutamic acid is not deaminated by the action of the L-amino acid oxidase of animal tissues and bacteria. But, in the presence of a specific enzyme, glutamic dehydrogenase, it undergoes oxidative deamination in the presence of either DPN or TPN. This reversible reaction gives a-iminoglutaric acid. 

De AngeUs, M., Calasso, M., Di Cagno, R., et al. (2010) NADP-glutamate dehydrogenase activity in non starter lactic acid bacteria effects of temperature, pH and NaQ on enzyme activity and expression. J Appl Microbiol 109, 1763-1774. 

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