Question

What are the three regulatory enzymes of the TCA cycle?

Answer 1

Tricarboxylic Acid Cycle is also called the citric acid cycle or Krebs cycle. It is the series of chemical reactions to release the stored energy by the oxidation process. Oxidation of acetyl coenzyme A comes from the carbohydrates, fats and proteins. This is used by organisms to generate energy. This process is done either by the aerobic or anaerobic respiration. This process also provides the precursor and reducing agent. It is important for many biochemical pathways.

Complete answer:
In eukaryotic cells TCA cycle happens in the Matrix of mitochondria. In this citric acid cycle three enzymes are involved. They are citrate synthase, isocitrate dehydrogenase and alpha ketoglutarate dehydrogenase. These enzymes are catalyzing the irreversible steps of the citric acid cycle. This is the main thing in the regulation process. Actually eight enzymes are participating in the TCA cycle. Acetyl coenzyme A is oxidized into the carbon dioxide. Citrate produced in this process is used in the fatty acid synthesis.
Citrate synthase is the first enzyme which regulates the citric acid cycle. It stands as the pace making enzyme and it is living in all living organisms. It is encoded by nuclear DNA except in the mitochondrial.
Isocitrate dehydrogenase is called the digestive enzyme. It is used to catalyze the oxidative decarboxylation of isocitrate into the alpha ketoglutarate. This encodes the mitochondrial protein and cytosolic protein.
Alpha ketoglutarate dehydrogenase is determining the metabolic flux through the citric acid cycle. It catalyses the alpha ketoglutarate to succinyl Coenzyme A and electrons produced directly the NADH which is used in the respiratory chain. It is the multiple copies of three enzymes.

Note:
Allosteric enzymes isocitrate dehydrogenase and alpha ketoglutarate dehydrogenase is the important enzyme used in the citric acid cycle. It is also called the Krebs cycle. These enzymes release the electrons to the complex of mitochondria. This electron reaches the active transport chain. Here build up of proton gradient occurs and this will drive the ATP production. This process is inhibited by the concentration of ATP, acetyl coenzyme A and NADH.