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

# Glucose-6-phosphate dehydrogenase (G6PD)

G6PD makes NADPH in the pentose pathway; in the red blood cell it is the only defence against oxidative damage.

Updated 2026-11-01

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## Key facts

- Glucose 6-phosphate + NADP⁺ → 6-phosphogluconolactone + NADPH: the rate-limiting step of the pentose phosphate pathway.
- The gene is on the X chromosome: deficiency mainly affects males; heterozygous women have variable activity.
- Besides the catalytic NADP⁺, each subunit has a structural NADP⁺ that stabilises it; many severe variants disturb that site.
- Deficiency gives partial protection against P. falciparum malaria, which explains its high frequency in malarial areas.

**EC number**
[1.1.1.49](https://www.enzyme-database.org/query.php?ec=1.1.1.49)

**Genes**
G6PD

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

## Regulation

- NADP⁺ activates it and NADPH inhibits it.
- Insulin and a carbohydrate-rich diet increase its synthesis in liver and adipose tissue.

## Inhibitors and toxins

- NADPH (product)
- Dehydroepiandrosterone (DHEA)

## Clinical notes

- G6PD deficiency causes acute haemolysis after fava beans, infections or oxidant drugs (primaquine, tafenoquine, dapsone, rasburicase, some sulfonamides).
- In Colombia, where P. vivax malaria is treated with primaquine, G6PD testing matters before that treatment.
- The smear shows Heinz bodies (oxidised haemoglobin) and bite cells.

## Pathways

- [Pentose phosphate pathway](https://durgical.com/en/biochemistry/pathways/pentose-phosphate-pathway/)

## Related conditions

- [Glucose-6-phosphate dehydrogenase (G6PD) deficiency](https://durgical.com/en/conditions/glucose-6-phosphate-dehydrogenase-deficiency/)
- [Malaria](https://durgical.com/en/conditions/malaria/)

## Related

- [Glucose 6-phosphate](https://durgical.com/en/biochemistry/molecules/glucose-6-phosphate/)
- [NADPH](https://durgical.com/en/biochemistry/molecules/nadph/)
- [Transketolase](https://durgical.com/en/biochemistry/enzymes/transketolase/)
- [Hemoglobin and 2,3-BPG](https://durgical.com/en/biochemistry/enzymes/hemoglobin-and-2-3-bpg/)

## Test yourself

Think of the answer, then tap the question to see it.

## Why does G6PD deficiency mainly affect the red cell?

The red cell has no mitochondria or other NADPH source; without it, it cannot regenerate reduced glutathione.

## How is G6PD deficiency inherited?

X-linked recessive: mainly men are affected.

## Which antimalarial requires knowing G6PD status before it is given?

Primaquine (and tafenoquine), which can cause severe haemolysis in deficient people.

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

Sources: [G6PD: Glucose-6-phosphate 1-dehydrogenase (human)](https://www.uniprot.org/uniprotkb/P11413/entry) (UniProt, 2026); [G6PD gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/g6pd/) (MedlinePlus, US National Library of Medicine, 2026); [2BHL: X-RAY STRUCTURE OF HUMAN GLUCOSE-6-PHOSPHATE DEHYDROGENASE (DELETION VARIANT) COMPLEXED WITH GLUCOSE-6-PHOSPHATE](https://www.rcsb.org/structure/2BHL) (RCSB Protein Data Bank, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/biochemistry/enzymes/glucose-6-phosphate-dehydrogenase/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/enzymes/glucose-6-phosphate-dehydrogenase/