In the citric acid cycle, a 4C oxaloacetic acid combines with 2C acetyl CoA to give rise to 6C citric acid. Isocitrate is an isomer of citric acid. The decarboxylation of citric acid produces a 5 C α -Ketoglutaric acid. This further undergoes decarboxylation to give rise to 4C succinic acid and further converts to 4C malic acid and oxaloacetic acid. Pyruvic acid or pyruvate is a 3C compound. A representation of the citric acid cycle (Krebs cycle) is given below: