Oxidative decarboxylation

Definition

Oxidative decarboxylation is a biochemical process in which a carboxyl group is removed from a molecule as carbon dioxide, while simultaneously oxidizing the molecule to produce energy-rich compounds like NADH. This reaction is crucial in cellular respiration as it links glycolysis and the citric acid cycle, playing a key role in the conversion of pyruvate to acetyl-CoA, and providing the necessary substrates for energy production in the citric acid cycle.

5 Must Know Facts For Your Next Test

1. Oxidative decarboxylation occurs in the mitochondria, where pyruvate from glycolysis is converted into acetyl-CoA and CO2.
2. The process involves the enzyme pyruvate dehydrogenase, which facilitates the conversion of pyruvate into acetyl-CoA and generates NADH as a byproduct.
3. This reaction is irreversible and serves as a key regulatory step in controlling the flow of carbon into the citric acid cycle.
4. NADH produced during oxidative decarboxylation is essential for oxidative phosphorylation, as it carries electrons to the electron transport chain.
5. Defects in oxidative decarboxylation can lead to metabolic disorders and are linked to conditions like pyruvate dehydrogenase deficiency.

Review Questions

• How does oxidative decarboxylation connect glycolysis and the citric acid cycle?
  • Oxidative decarboxylation acts as a bridge between glycolysis and the citric acid cycle by converting pyruvate, the end product of glycolysis, into acetyl-CoA. This conversion occurs in the mitochondria and involves removing a carboxyl group from pyruvate while generating NADH. The produced acetyl-CoA then enters the citric acid cycle, where it is further oxidized to produce ATP and other high-energy carriers.
• Discuss the significance of NADH generated during oxidative decarboxylation in relation to energy production.
  • NADH generated during oxidative decarboxylation is critical for energy production because it serves as an electron carrier that transports electrons to the electron transport chain. This chain is responsible for oxidative phosphorylation, where ATP is produced through chemiosmosis. The amount of NADH produced from oxidative decarboxylation directly impacts how much ATP can be synthesized later on, highlighting its importance in cellular respiration.
• Evaluate the impact of disruptions in oxidative decarboxylation on cellular metabolism and overall energy homeostasis.
  • Disruptions in oxidative decarboxylation can severely impact cellular metabolism by inhibiting the conversion of pyruvate to acetyl-CoA, leading to reduced entry of carbon into the citric acid cycle. This results in lower production of ATP and NADH, ultimately affecting energy homeostasis within cells. Such metabolic imbalances may contribute to various health issues, including neurological disorders due to insufficient energy supply, illustrating how crucial this process is for maintaining normal cellular functions.

Related terms

NADH: A coenzyme that acts as an electron carrier in metabolic processes, playing a vital role in transferring electrons during cellular respiration.

Acetyl-CoA: A central metabolite that is formed from the decarboxylation of pyruvate, which enters the citric acid cycle to generate ATP.

Citric Acid Cycle: A series of chemical reactions used by all aerobic organisms to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.