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[Biochemistry](https://durgical.com/en/biochemistry/) · Enzyme

# Pyruvate kinase

Pyruvate kinase makes the last step of glycolysis and its second ATP; if it fails in red cells, they are destroyed too early.

Updated 2026-10-31

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## Key facts

- Phosphoenolpyruvate + ADP → pyruvate + ATP, with Mg²⁺ and K⁺; irreversible.
- Isoforms: L (liver) and R (red cell) from PKLR; M1 (muscle, brain) and M2 (dividing cells, tumours) from PKM.
- Fructose 1,6-bisphosphate activates it ahead of time.

**EC number**
[2.7.1.40](https://www.enzyme-database.org/query.php?ec=2.7.1.40)

**Genes**
PKLR, PKM

**Structure (PDB)**
[2VGB](https://www.rcsb.org/structure/2VGB)

## Regulation

- Activator: fructose 1,6-bisphosphate. Inhibitors: ATP and alanine.
- In the liver, glucagon phosphorylates it (PKA) and switches it off so that phosphoenolpyruvate goes to gluconeogenesis.

## Inhibitors and toxins

- Alanine (signal that pyruvate is plentiful)

## Clinical notes

- Red-cell pyruvate kinase deficiency (autosomal recessive) causes chronic hemolytic anemia, jaundice, an enlarged spleen and gallstones.
- In that deficiency 2,3-BPG builds up: hemoglobin releases oxygen more easily and the anemia is better tolerated.
- Mitapivat, a pyruvate kinase activator, is an approved treatment for adults with this deficiency.

## Pathways

- [Glycolysis](https://durgical.com/en/biochemistry/pathways/glycolysis/)

## Related conditions

- [Pyruvate kinase deficiency](https://durgical.com/en/conditions/pyruvate-kinase-deficiency/)

## Related

- [Pyruvate](https://durgical.com/en/biochemistry/molecules/pyruvate/)
- [ATP (adenosine triphosphate)](https://durgical.com/en/biochemistry/molecules/atp/)
- [Hemoglobin and 2,3-BPG](https://durgical.com/en/biochemistry/enzymes/hemoglobin-and-2-3-bpg/)
- [Fructose 1,6-bisphosphate](https://durgical.com/en/biochemistry/molecules/fructose-1-6-bisphosphate/)

## Test yourself

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## Which metabolite activates pyruvate kinase ahead of time?

Fructose 1,6-bisphosphate, the product of PFK-1.

## Why does pyruvate kinase deficiency cause hemolysis?

Without enough ATP the red cell loses control of its ions and shape, and the spleen removes it.

## Which gene encodes red-cell pyruvate kinase?

PKLR (the R and L isoforms).

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: [PKLR: Pyruvate kinase PKLR (human)](https://www.uniprot.org/uniprotkb/P30613/entry) (UniProt, 2026); [Pyruvate kinase deficiency: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/pyruvate-kinase-deficiency/) (MedlinePlus, US National Library of Medicine, 2026); [PKLR gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/pklr/) (MedlinePlus, US National Library of Medicine, 2026); [2VGB: Human erythrocyte pyruvate kinase](https://www.rcsb.org/structure/2VGB) (RCSB Protein Data Bank, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/biochemistry/enzymes/pyruvate-kinase/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/enzymes/pyruvate-kinase/