Succinate dehydrogenase

Definition

Succinate dehydrogenase is an enzyme that plays a critical role in the citric acid cycle (Krebs cycle) and the electron transport chain by catalyzing the oxidation of succinate to fumarate while reducing flavin adenine dinucleotide (FAD) to FADH2. This enzyme is unique as it is the only enzyme that participates in both the citric acid cycle and oxidative phosphorylation, making it vital for cellular respiration and energy production.

5 Must Know Facts For Your Next Test

1. Succinate dehydrogenase is located in the inner mitochondrial membrane, making it integral to the process of energy production.
2. The enzyme uses FAD as a cofactor, which allows it to accept electrons during the conversion of succinate to fumarate.
3. Mutations in succinate dehydrogenase can lead to various diseases, including certain types of cancer and mitochondrial disorders.
4. Succinate dehydrogenase has four subunits in its complex: two subunits are responsible for binding succinate and FAD, while the other two subunits help in anchoring the enzyme within the membrane.
5. It participates in both aerobic and anaerobic respiration, highlighting its versatility in cellular metabolism.

Review Questions

• How does succinate dehydrogenase contribute to both the citric acid cycle and oxidative phosphorylation?
  • Succinate dehydrogenase links the citric acid cycle and oxidative phosphorylation by catalyzing the conversion of succinate to fumarate while reducing FAD to FADH2. The FADH2 produced is then used in the electron transport chain during oxidative phosphorylation to generate ATP. This dual role emphasizes its importance in energy metabolism, facilitating efficient energy production within cells.
• Discuss the implications of mutations in succinate dehydrogenase on human health.
  • Mutations in succinate dehydrogenase can lead to a range of health issues, particularly certain hereditary cancers such as paragangliomas and pheochromocytomas. These mutations disrupt normal enzymatic function, leading to an accumulation of succinate, which can promote tumorigenesis. The dysfunction also contributes to mitochondrial disorders, showcasing how crucial this enzyme is for proper metabolic functioning.
• Evaluate how succinate dehydrogenase serves as a bridge between different metabolic pathways and its overall impact on cellular respiration.
  • Succinate dehydrogenase acts as a critical junction between the citric acid cycle and oxidative phosphorylation, highlighting its role in linking different metabolic pathways. By converting succinate to fumarate, it not only produces FADH2 for the electron transport chain but also ensures continuous flow within the Krebs cycle. This connection enhances cellular respiration efficiency, ultimately affecting ATP production and cellular energy availability, which are essential for overall cellular function.

Related terms

Citric Acid Cycle: A series of enzymatic reactions that occur in the mitochondria, where acetyl-CoA is oxidized to produce ATP, NADH, and FADH2, contributing to cellular respiration.

FADH2: A reduced form of flavin adenine dinucleotide that carries electrons to the electron transport chain, generated during the citric acid cycle and other metabolic pathways.

Oxidative Phosphorylation: The metabolic process that uses the energy from electron transport chains to produce ATP from ADP and inorganic phosphate, occurring in the inner mitochondrial membrane.