Which substrates and coenzymes are required for the enzymatic measurement of ammonia?

The enzymatic measurement of ammonia typically involves the conversion of ammonia to other compounds through a series of biochemical reactions that require specific substrates and coenzymes. In this context, the combination of α-ketoglutarate and NADH is significant because they are involved in the enzymatic reaction catalyzed by glutamate dehydrogenase.

In the reaction, glutamate dehydrogenase catalyzes the oxidative deamination of glutamate, which utilizes α-ketoglutarate to accept the amino group removed from the glutamate, producing ammonia and glutamate. During this process, NAD+ is reduced to NADH. The presence of α-ketoglutarate serves as the substrate that accepts the amino group, while NADH acts as the coenzyme that facilitates the transfer of electrons. The amount of NADH generated can be quantified, which is proportional to the ammonia concentration in the sample.

This particular measurement approach is essential in clinical settings for assessing ammonia levels, especially in cases of liver dysfunction or metabolic disorders. The use of α-ketoglutarate and NADH in this enzymatic process reflects a well-established biochemical pathway that is critical in the evaluation of ammonia in clinical chemistry.