Biochemistry · Molecule
Citrate !
Citrate is the first molecule of the Krebs cycle; it also carries acetyl to the cytosol to make fat and slows glycolysis when energy is plentiful.
Updated 2026-10-31
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Key facts
- A six-carbon tricarboxylic acid: citrate synthase makes it from acetyl-CoA and oxaloacetate.
- Outside the mitochondria, ATP-citrate lyase splits it back into acetyl-CoA for fatty acid synthesis.
- It inhibits PFK-1 and activates acetyl-CoA carboxylase.
- Also called
- Citric acid
- Formula
- C₆H₈O₇
- PubChem
- CID 311
Structure
- It is symmetric, yet aconitase treats it as asymmetric: the two carbons that enter as acetyl do not leave as CO₂ in that turn.
Clinical notes
- Citrate binds calcium: that is why it anticoagulates stored blood, and too much in massive transfusions lowers ionised calcium.
- In urine, citrate prevents calcium stones; potassium citrate is used to prevent them.
Pathways
Related conditions
Related
Test yourself
Think of the answer, then tap the question to see it.
Which glycolysis enzyme does citrate inhibit?
Phosphofructokinase-1.
Why does citrate anticoagulate banked blood?
It chelates calcium, which clotting needs.
How does acetyl-CoA leave the mitochondria to make fat?
As citrate; in the cytosol ATP-citrate lyase releases the acetyl-CoA.
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: Citric acid (CID 311) (PubChem, NCBI, 2026) · Public domain; Citric acid cycle (TCA cycle) (Reactome, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).
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