1. Condensation: Acetyl CoA reacts with oxaloacetic acid to produce citric acid under the action of acetyl CoA condensing enzyme with the help of citrate synthetase.
2. Isomerization: Under the action of aconitase enzyme, cis-aconitic acid is produced from citric acid and then isocitric acid from cis-aconitic acid.
3. Dehydrogenation: Oxalosuccinic acid is produced from isocitric acid by the action of isocitrate dehydrogenase enzyme. At this time, NADP participates in the reaction and produces NADPH+H+. The reaction is bidirectional.
4. Decarboxylation: Under the action of oxalo succinate carboxylase enzyme, oxalo succinic acid is converted into alpha keto glutaric acid.
5. Oxidative decarboxylation: Succinyl Co is produced from alpha ketoglutaric acid with the help of alpha ketoglutarate dehydrogenase enzyme. At this time NADP participates in the reaction NADPH+H+
produces
6. ATP Synthesis: Succinic acid is produced from succinyl CoA in the presence of succinyl CoA synthetase enzyme. During this reaction, ADP takes part and produces ATP. The reaction is bidirectional.
7. Dehydrogenation: Fumaric acid is produced from succinic acid by the action of succinyl dehydrogenase enzyme. FAD participates in the reaction and produces FADH2. The reaction is bidirectional.
8. Hydration: Fumaric acid is converted to malic acid in the presence of fumarase enzyme. The reaction is bidirectional.
9. Dehydrogenation: Oxaloacetic acid is produced from malic acid with the help of malate dehydrogenase enzyme. At this time, NADP participates in the reaction and produces NADPH+H+.
The oxaloacetic acid produced then re-enters the Krebs cycle and keeps the cycle going.