L-Glutamic acid dehydrogenase

L-Glutamic acid dehydrogenase was discovered independently by von Euler et al. (4) and Dewan (5). Crystallization of this enzyme was achieved by Olson and Anfinsen (d) from beef liver and by Snoke (7) from chicken liver. 

Table 10.8 Enzyme activity of L-glutamic acid dehydrogenase in the presence of surfactants (from [64])...

L-glutamic acid C. melassecola C. melassecola Glu A, citrate dehydrogenase, ppc, aconitate dehydratase ... 

Glutamic acid dehydrogenase is widely distributed in microorganisms and higher plants as a catalyst in the synthesis of L-glutamic acid from a-ketoglutaric acid and free ammonia. Transaminase is contained in a wide variety of microorganisms. 

The effect is mainly due to the inhibition of NAD+-dependent aldehyde dehydrogenase (ALDH) which causes an accumulation of acetaldehyde in the body after ethanol ingestion [17]. The compound responsible for the physiological activity of C. atramentarius is coprine 16, a AT -(l-hydroxycyclopropyl)-L-glutamic acid amide which has been isolated and synthesized, [16a,b]. Thus, when fed... 

Reaction of 1 with ATP in presence of Mg and kinase gives 2-amino-4-hy-droxy-6-hydroxymethyldihydropteridine pyrophosphate (2, DHP pyrophosphate). The latter is converted into 7,8-dihydropteroate (3, DHP) by its reaction with p-ami-nobenzoic acid (PABA) and DHP synthetase. Addition of L-glutamic acid to DHP in the presence of the enzyme dihydrofolate synthetase (DHF synthetase) yields 7,8-di-hydrofolate (4, DHF), which undergoes reduction by the enzyme dihydrofolate reductase to afford 5,6,7,8-tetrahydrofolate (5, THF). DHF may also lose a hydrogen molecule in the presence of DHF dehydrogenase to form folic acid (6). 

When the ink-cap mushroom Coprinus atramentarius is eaten alone it is not toxic. However, if it is eaten with alcohol it induces an over-sensitivity that is similar to that of the drug disulphiram (antabuse). The fresh mushroom contains about 160 mg kg of the active component, coprine (9.34). This was shown to be A -(l-hydroxycyclopropyl)-L-glutamine, which contains the unusual Wacyl-l-aminocyclopropanol unit. It is metabolized to L-glutamic acid and cyclopropanone. The hydrate of cyclopropanone is a good inhibitor of acetaldehyde dehydrogenase. This induces elevated levels of acetaldehyde in the blood and retards the rate of ethanol metabolism. 

L-Glutamate dehydrogenases (EC 1.4.1.2-4) catalyze the interconversion of a-ketoglutarate and L-glutamic acid ... 

L-Glutamic acid is formed from (%-ketoglutaric acid, an intermediate of the tri-carbonic acid cycle (D 5) by glutamate dehydrogenase. It is transformed reversibly to L-proline and L-ornithine (Fig. 217). 

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. 

L-glutamate dehydrogenase L-glutamate test for citric acid cycle... 

Transamination channels a-amino acid nitrogen into glutamate. L-Glutamate dehydrogenase (GDH) occupies a central position in nitrogen metabolism. 

L)-Phosphinotricin 67, which is the active component of naturally occurring antibiotic biolaphos, was synthesized from the corresponding keto acid 66 via reductive amination catalysed by L-glutamate dehydrogenase (EDH) (Equation 32)7 ... 

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