Under which of the following conditions would you most likely expect the glutamate dehydrogenase reaction to proceed in the direction of glutamate synthesis?
A) high ATP:ADP ratio
B) high NADH levels
C) high NADPH levels
D) low NADH levels
E) low NADPH levels

Question

Quizplus · Accepted Answer

Glutamate dehydrogenase utilizes both nicotinamide nucleotide cofactors; NAD+ in the direction of nitrogen liberation and NADP+ for nitrogen incorporation. In the forward reaction (as shown in Figure 29-3) glutamate dehydrogenase is important in converting free ammonia and a-ketoglutarate to glutamate. The reverse reaction is a key anapleurotic process linking amino acid metabolism with TCA cycle activity. In the reverse reaction, glutamate dehydrogenase provides an oxidizable carbon source used for the production of energy as well as a reduced electron carrier, NADH. As expected for a branch point enzyme with an important link to energy metabolism, glutamate dehydrogenase is regulated by the cell energy charge. ATP and GTP are positive allosteric effectors of the formation of glutamate, whereas ADP and GDP are positive allosteric effectors of the reverse reaction. Thus, when the level of ATP is high, conversion of glutamate to a-ketoglutarate and other TCA cycle intermediates is limited; when the cellular energy charge is low, glutamate is converted to ammonia and oxidizable TCA cycle intermediates.

Under Which of the Following Conditions Would You Most Likely