Question

GDH pathway is predominant when cellular environment rich in C sources whilst low concentration ammonia. on the other hand, GS/GOGAT pathway is predominant in opposite condition. TRUE or FALSE. please explain your answer.

Answer 1

Answer:-

The above statement is False.

Glutamic acid and glutamine play a prominent role in the assimilation of ammonia by microorganisms. There are generally two pathways which are involved in the incorporation of the ammonia into glutamic acid. One is GDH( glutamate dehydrogenase) pathway and other is GS(glutamine synthase) or GOGAT(glutamate synthase) pathway. It is the GDH pathway which is predominant pathway for ammonia assimilation in ammonia rich medium. The intracellular concentration of in the nitrogen fixing cells is more than that of GOGAT pathway. The GDH pathway has relatively high $K_m$ value with higher folds than that of GOGAT pathway. The GOGAT pathway is basically an alternate pathway for ammonia assimilation and it works when there is low levels of ammonia present in the growth medium. At high level of ammonia , the deactivation and repression of GOGAT pathway takes place whereas initiation of the GDH pathway be enacted. Both the pathways are involved in producing one mole of glutamate from the one mole of each $NH_3$ , 2- oxoglutarate and NADPH. But the GOGAT pathway is more expensive than GDH pathway as it consumes one ATP during the glutamate biosynthesis.

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