Citric Acid Cycle

step 1

• oxaloacetate —> citrate

• acetyl-CoA —> CoA

• citrate synthase

• regulatory step

step 2

• citrate —> isocitrate

• aconitase

step 3

• isocitrate —> 𝛂-ketoglutarate

• NAD⁺ —> NADH + CO₂

• isocitrate dehydrogenase

• regulatory step

step 4

• 𝛂-ketoglutarate —> succinyl CoA

• NAD⁺ + CoA —> NADH + CO₂

• 𝛂-ketoglutarate dehydrogenase complex

• regulatory step

step 5

• succinyl CoA —> succinate

• GDP + P_i —> GTP + CoA

• succinyl CoA synthetase

step 6

• succinate —> fumarate

• FAD —> FADH₂

• succinate dehydrogenase

step 7

• fumurate —> malate

• requires H₂O

• fumarase

step 8

• malate —> oxaloacetate

• NAD⁺ —> NADH + H⁺

• malate dehydrogenase

regulatory enzymes

• citrate synthase

• isocitrate dehydrogenase

• 𝛂-ketoglutarate dehydrogenase complex

net yield

• 1 GTP

• 3 NADH

• 1 FADH₂

entry molecule

acetyl-CoA

citrate synthase inhibitors

• ATP

• NADH

• citrate

• succinyl-CoA

citrate synthase activators

• ADP

isocitrate dehydrogenase inhibitors

• ATP

• NADH

isocitrate dehydrogenase activators

• ADP

• NAD⁺

𝛂-ketoglutarate dehydrogenase complex inhibitors

• succinyl-CoA

• NADH

• ATP

𝛂-ketoglutarate dehydrogenase complex activators

• ADP

rate-limiting enzyme

isocitrate dehydrogenase

location

mitochondrial matrix