Biochemistry · Enzyme
α-Ketoglutarate dehydrogenase !
α-Ketoglutarate dehydrogenase is PDH's twin inside the cycle: it releases the second CO₂ and uses the same vitamins.
Updated 2026-10-31
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Key facts
- α-Ketoglutarate + CoA + NAD⁺ → succinyl-CoA + CO₂ + NADH; irreversible.
- Same design as PDH: E1 (thiamine pyrophosphate), E2 (lipoate) and a shared E3 (FAD, NAD⁺).
- The 3D model is E. coli E1, the most complete structure available.
Regulation
- Succinyl-CoA, NADH and ATP inhibit it; Ca²⁺ activates it. Unlike PDH, it is not regulated by phosphorylation.
Inhibitors and toxins
- Arsenite (lipoic acid)
Clinical notes
- It is very sensitive to thiamine deficiency and oxidative stress; its failure in neurons contributes to Wernicke encephalopathy.
- α-Ketoglutarate also links the cycle to amino acids: glutamate is made and broken down through it.
Pathways
Related conditions
Related
Test yourself
Think of the answer, then tap the question to see it.
Which enzyme shares E3 with α-ketoglutarate dehydrogenase?
Pyruvate dehydrogenase (and the branched-chain keto acid dehydrogenase).
Which product inhibits α-ketoglutarate dehydrogenase?
Succinyl-CoA (as well as NADH).
Which vitamin, when lacking, slows this enzyme and PDH at once?
Thiamine (B1).
Educational information, not medical advice. For any symptom, see a health professional.
Sources: OGDH: 2-oxoglutarate dehydrogenase complex component E1 (human) (UniProt, 2026); Citric acid cycle (TCA cycle) (Reactome, 2026); 2JGD: E. coli 2-oxoglutarate dehydrogenase (E1o) (RCSB Protein Data Bank, 2026).
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Representative model, for educational purposes only.