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

# Superoxide dismutase (SOD)

Superoxide dismutase turns the superoxide radical into hydrogen peroxide and oxygen; it is the first antioxidant line.

Updated 2026-11-01

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## Key facts

- 2 O₂•⁻ + 2 H⁺ → H₂O₂ + O₂; catalase or glutathione peroxidase then remove the H₂O₂.
- Three forms: SOD1 with copper and zinc (cytosol), SOD2 with manganese (mitochondrial matrix, next to the chain) and SOD3 (extracellular).
- It is one of the fastest enzymes known: it works almost at the rate of diffusion.
- Copper changes valence in the reaction; zinc stabilises the structure.

**Also called**
SOD1, SOD2, SOD3

**EC number**
[1.15.1.1](https://www.enzyme-database.org/query.php?ec=1.15.1.1)

**Genes**
SOD1, SOD2, SOD3

**Structure (PDB)**
[2C9V](https://www.rcsb.org/structure/2C9V)

## Regulation

- SOD2 is induced by inflammatory cytokines and oxidative stress.
- It needs copper, zinc or manganese depending on the form: deficiency lowers activity.

## Inhibitors and toxins

- Diethyldithiocarbamate (copper chelator, experimental use)

## Clinical notes

- SOD1 variants cause part of familial amyotrophic lateral sclerosis; the damage comes from the misfolded protein, not only from lost activity.
- Neutrophils use superoxide to kill microbes: SOD turns it into H₂O₂, which myeloperoxidase converts to hypochlorite.

## Related

- [Catalase](https://durgical.com/en/biochemistry/enzymes/catalase/)
- [Glutathione peroxidase (GPX)](https://durgical.com/en/biochemistry/enzymes/glutathione-peroxidase/)
- [Reactive oxygen species and antioxidants](https://durgical.com/en/biochemistry/topics/reactive-oxygen-species-and-antioxidants/)
- [Complex I (NADH dehydrogenase)](https://durgical.com/en/biochemistry/enzymes/complex-i/)
- [Complex III (cytochrome bc₁)](https://durgical.com/en/biochemistry/enzymes/complex-iii/)

## Test yourself

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

## What reaction does superoxide dismutase catalyse?

It turns two superoxides into H₂O₂ and O₂; catalase and glutathione peroxidase then remove the H₂O₂.

## Which metal does mitochondrial SOD contain?

Manganese (SOD2); the cytosolic form (SOD1) has copper and zinc.

## Which neurological disease is linked to SOD1 variants?

Familial amyotrophic lateral sclerosis.

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

Sources: [SOD1: Superoxide dismutase [Cu-Zn] (human)](https://www.uniprot.org/uniprotkb/P00441/entry) (UniProt, 2026); [SOD2: Superoxide dismutase [Mn], mitochondrial (human)](https://www.uniprot.org/uniprotkb/P04179/entry) (UniProt, 2026); [SOD1 gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/sod1/) (MedlinePlus, US National Library of Medicine, 2026); [Amyotrophic lateral sclerosis: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/amyotrophic-lateral-sclerosis/) (MedlinePlus, US National Library of Medicine, 2026); [2C9V: Atomic resolution structure of Cu-Zn Human Superoxide dismutase](https://www.rcsb.org/structure/2C9V) (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/superoxide-dismutase/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/enzymes/superoxide-dismutase/