Isocitrate

Definition

Isocitrate is a six-carbon compound that plays a crucial role in the citric acid cycle as an intermediate formed from citrate and subsequently converted to alpha-ketoglutarate. It is essential for the proper functioning of cellular respiration, participating in energy production through a series of enzymatic reactions. Isocitrate also links carbohydrate metabolism with fatty acid metabolism, illustrating its significance in energy balance within the cell.

5 Must Know Facts For Your Next Test

1. Isocitrate is formed when citrate undergoes an isomerization reaction, catalyzed by the enzyme aconitase.
2. The conversion of isocitrate to alpha-ketoglutarate involves the enzyme isocitrate dehydrogenase, which reduces NAD+ to NADH and releases CO2.
3. Isocitrate can be utilized in anabolic processes as it serves as a precursor for various biosynthetic pathways, linking energy production to macromolecule synthesis.
4. The regulation of isocitrate levels is crucial for maintaining metabolic homeostasis, influencing both the citric acid cycle and oxidative phosphorylation.
5. Disruption in isocitrate metabolism has been associated with certain metabolic disorders and cancers, highlighting its importance in cellular function.

Review Questions

• How does isocitrate function as an intermediate in the citric acid cycle, and what are the implications of its conversion to alpha-ketoglutarate?
  • Isocitrate serves as a critical intermediate in the citric acid cycle, formed from citrate and then transformed into alpha-ketoglutarate by the enzyme isocitrate dehydrogenase. This conversion not only releases carbon dioxide but also generates NADH, which contributes to the overall energy yield during cellular respiration. The transformation of isocitrate signifies a key regulatory point in the cycle, linking carbon metabolism to energy production and influencing metabolic flux.
• Discuss how disruptions in isocitrate metabolism could impact overall cellular respiration and energy production.
  • Disruptions in isocitrate metabolism can significantly impact cellular respiration by affecting the flow through the citric acid cycle. Since isocitrate plays a role in connecting various metabolic pathways, any changes can lead to altered NADH production and energy yield. For example, insufficient conversion of isocitrate may decrease ATP production and impair essential biosynthetic processes, ultimately affecting cell growth and function.
• Evaluate the broader significance of isocitrate in linking carbohydrate metabolism with fatty acid metabolism within the context of cellular energy balance.
  • Isocitrate serves as a vital link between carbohydrate and fatty acid metabolism by providing intermediates that can feed into various biosynthetic pathways. This connection helps maintain cellular energy balance, allowing cells to efficiently switch between using carbohydrates and fats based on availability. The ability of isocitrate to act in this dual capacity highlights its importance not just for energy production but also for supporting cell growth and adaptation to metabolic changes, showcasing its central role in bioenergetics.

Related terms

Citrate: Citrate is a six-carbon compound that is the first product formed in the citric acid cycle, synthesized from acetyl-CoA and oxaloacetate.

Alpha-ketoglutarate: Alpha-ketoglutarate is a five-carbon compound that is formed from isocitrate through oxidative decarboxylation during the citric acid cycle.

NADH: NADH is a reduced coenzyme produced during various metabolic pathways, including the citric acid cycle, that plays a key role in transferring electrons to the electron transport chain.