Biochemistry · Molecule
Acetoacetate (acetoacetic acid) !
Acetoacetate is the first ketone body the liver makes; other tissues turn it back into acetyl-CoA.
Updated 2026-11-01
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Key facts
- Released by HMG-CoA lyase in liver mitochondria.
- It is reduced to β-hydroxybutyrate (BDH1) or loses CO₂ on its own to form acetone.
- In tissues SCOT activates it to acetoacetyl-CoA, which gives 2 acetyl-CoA.
- It is what the nitroprusside strip detects in urine and blood.
- Also called
- 3-Oxobutanoic acid
- Formula
- C₄H₆O₃
- PubChem
- CID 96
Structure
- A 4-carbon β-keto acid: keto group at C3 and carboxyl at C1, which is why it decarboxylates easily.
Clinical notes
- The acetone it forms gives the fruity breath of ketoacidosis.
- The nitroprusside strip can underestimate ketosis when β-hydroxybutyrate predominates.
Pathways
- Ketogenesis (ketone body synthesis)
- Phenylalanine and tyrosine metabolism
- Branched-chain amino acid breakdown (leucine route)
Related conditions
Related
- β-Hydroxybutyrate
- Mitochondrial HMG-CoA synthase (HMGCS2)
- β-Hydroxybutyrate dehydrogenase (BDH1)
- Succinyl-CoA:3-ketoacid CoA transferase (SCOT)
- Acetyl-CoA
Test yourself
Think of the answer, then tap the question to see it.
Which enzyme produces acetoacetate?
HMG-CoA lyase, which splits HMG-CoA into acetoacetate and acetyl-CoA.
Where does the acetone on the breath in ketoacidosis come from?
From spontaneous decarboxylation of acetoacetate.
Which ketone body does the nitroprusside strip detect?
Acetoacetate (and to a lesser degree acetone), not β-hydroxybutyrate.
Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Acetoacetic Acid (CID 96) (PubChem, NCBI, 2026) · Public domain; Synthesis of Ketone Bodies (Reactome, 2026); Ketones urine test: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026).
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