During which metabolic process is NADH formed from amino acid deamination?

NADH is produced during the deamination of amino acids, which is a part of protein catabolism. During this metabolic process, amino acids lose an amino group, resulting in a carbon skeleton that can be further processed for energy production or converted into other biomolecules.

In protein catabolism, the amino acids are deaminated primarily in the liver. This process not only removes the amino group but also leads to the formation of α-keto acids. The accompanying reactions often involve the reduction of NAD+ to NADH. This is significant because NADH serves as a crucial electron carrier, transporting electrons to the electron transport chain for ATP production.

While other processes like the Krebs Cycle and glycolysis also involve NADH production, they are not specifically linked to the deamination of amino acids. The Krebs Cycle primarily focuses on the oxidation of acetyl-CoA derived from carbohydrates, fatty acids, or amino acids, and glycolysis is the pathway for glucose breakdown. Therefore, the specific context of amino acid deamination aligns with protein catabolism being the correct answer, as that is where NADH is directly formed from this process.