Isocitrate

Definition

Isocitrate is a six-carbon intermediate compound in the citric acid cycle, formed from citrate by the enzyme aconitase. It plays a crucial role in energy production as it is further processed to produce NADH and ATP, contributing to cellular respiration and energy metabolism.

5 Must Know Facts For Your Next Test

1. Isocitrate undergoes oxidative decarboxylation to form alpha-ketoglutarate, producing NADH and releasing carbon dioxide in the process.
2. The enzyme that converts citrate to isocitrate, aconitase, operates through a two-step process involving cis-aconitate as an intermediate.
3. Isocitrate levels can influence metabolic pathways, including those related to amino acid synthesis and fatty acid metabolism.
4. Inhibition or malfunction of the isocitrate dehydrogenase enzyme can lead to metabolic disorders and has been implicated in certain types of cancer.
5. Isocitrate also plays a role in gluconeogenesis and acts as a signaling molecule for various metabolic pathways.

Review Questions

• How does isocitrate contribute to the overall function of the citric acid cycle?
  • Isocitrate plays a key role in the citric acid cycle by being an important intermediate that connects citrate to alpha-ketoglutarate. Its conversion involves oxidative decarboxylation, which generates NADH while releasing carbon dioxide. This step is crucial for energy production, as NADH will later contribute to the electron transport chain, highlighting isocitrate's essential position in cellular respiration.
• Discuss the enzymatic process involving aconitase and its significance in the conversion of citrate to isocitrate.
  • The conversion of citrate to isocitrate involves the enzyme aconitase, which facilitates this transformation through a two-step reaction. First, citrate is converted to an intermediate called cis-aconitate before being transformed into isocitrate. This enzymatic process is significant because it ensures the proper flow of metabolites through the citric acid cycle, maintaining efficient energy production in cells.
• Evaluate how disruptions in the metabolism of isocitrate can lead to broader implications in human health and disease.
  • Disruptions in the metabolism of isocitrate can have significant implications for human health, particularly through its role in metabolic disorders and cancer. For instance, mutations or malfunctions in isocitrate dehydrogenase can alter normal cellular energy production and contribute to tumorigenesis. Additionally, abnormal levels of isocitrate can affect various metabolic pathways, leading to imbalances that can manifest as chronic diseases or metabolic syndromes.

Related terms

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

Aconitase: Aconitase is an enzyme that catalyzes the conversion of citrate to isocitrate, facilitating the isomerization process in the citric acid cycle.

NADH: NADH is a coenzyme that carries electrons to the electron transport chain, playing a key role in energy production during cellular respiration.