How many times decarboxylation occurs during each TCA cycle ?

During each turn of the citric acid cycle (also known as the tricarboxylic acid cycle or TCA cycle), decarboxylation occurs twice. Decarboxylation is the process of removing a carboxyl group (-COOH) from a molecule, resulting in the release of carbon dioxide (CO₂).

The two decarboxylation reactions in the TCA cycle occur during the following steps:

(1) Isocitrate to $\alpha$-ketoglutarate: Isocitrate is first converted to $\alpha$-ketoglutarate by the enzyme isocitrate dehydrogenase.
In this reaction, a carboxyl group is removed from isocitrate, and carbon dioxide is released.

(2) $\alpha$-ketoglutarate to succinyl-CoA: $\alpha$-ketoglutarate is then converted to succinyl-CoA by the enzyme $\alpha$-ketoglutarate dehydrogenase complex. Similar to the previous step, a carboxyl group is removed from $\alpha$-ketoglutarate, resulting in the release of carbon dioxide.