Question

What are the 3 regulatory enzymes of the TCA cycle?

Answer 1

TCA cycle:

1. The tricarboxylic Acid Cycle (TCA) is also called the citric acid cycle or Krebs cycle.
2. This is a series of chemical reactions to release the stored energy by the oxidation process.
3. Oxidation of acetyl coenzyme A comes from carbohydrates, fats, and proteins.
4. It is used by organisms to generate energy.
5. It can be either aerobic or anaerobic respiration.
6. The three regulatory enzymes of the TCA cycle are citrate synthase, isocitrate dehydrogenase, and α-ketoglutarate dehydrogenase.

• Citrate synthase: Citrate synthase is the first enzyme that regulates the citric acid cycle.

1. It acts as the pace-making enzyme and it is living in all living organisms.
2. It is encoded by nuclear DNA except in the mitochondrial.

• Isocitrate dehydrogenase: It is called the digestive enzyme.

1. It is used to catalyze the oxidative decarboxylation of isocitrate into the alpha-ketoglutarate.
2. This encodes the mitochondrial protein and cytosolic protein.

• α-ketoglutarate dehydrogenase: It dehydrogenase is determining the metabolic flux through the citric acid cycle.

1. It catalyzes the alpha-ketoglutarate to succinyl Coenzyme A and electrons are produced directly the NADH which is used in the respiratory chain.
2. These enzymes are allosterically regulated and catalyze the irreversible steps of the TCA cycle, which are the main point of regulation.