The chemical reactions concerned to fill up the intermediates in any metabolic pathway are called anaplerosis or anaplerotic reactions. Examples of such anaplerotic reactions are found in TCA cycle (citric acid cycle). The sailent features of anaplerotic reactions are given in the following steps.

First, Pyruvate carboxylase catalyses the conversion of pyruvate to oxaloacetate. It is an ATP dependent reaction which involves carboxylation.

Secondly, the conversion of pyruvate takes place by NADP⁺ dependent malate dehydrogenase enzyme (malic enzyme).

The process by which amino acid gets converted to keto acid after transferring its amino group to keto acid is called transamination. α-Ketoglutarate is formed by this mechanism.

α-Ketoglutarate can be synthesized from glutamate by glutamate dehydrogenase reaction:

The anaplerotic reactions of TCA cycle were explained.