Peroxidase

File:GlutPeroxidase-1GP1.pngGlutathione Peroxidase 1

Peroxidases (EC number 1.11.1.x) are a large family of enzymes. A majority of peroxidase protein sequences can be found in the PeroxiBase database. Peroxidases typically catalyze a reaction of the form:

ROOR' + electron donor (2 e-) + 2H+ → ROH + R'OH

For many of these enzymes the optimal substrate is hydrogen peroxide, but others are more active with organic hydroperoxides such as lipid peroxides. Peroxidases can contain a heme cofactor in their active sites, or redox-active cysteine or selenocysteine residues.

The nature of the electron donor is very dependent on the structure of the enzyme.

* For example, horseradish peroxidase can use a variety of organic compounds as electron donors and acceptors. Horseradish peroxidase has an accessible active site and many compounds can reach the site of the reaction.
* For an enzyme such as cytochrome c peroxidase, the compounds that donate electrons are very specific, because there is a very closed active site.

While the exact mechanisms have yet to be elucidated, peroxidases are known to play a part in increasing a plant's defenses against pathogens.[1] Peroxidases are sometimes used as histological marker. Cytochrome c peroxidase is used as a soluble, easily purified model for cytochrome c oxidase.

Glutathione peroxidase is a peroxidase found in humans, which contains selenocysteine. It uses glutathione as an electron donor and is active with both hydrogen peroxide and organic hydroperoxide substrates.

Amyloid beta, when bound to heme has been shown to have peroxidase activity.[2]

## See also

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* Myeloperoxidase (MPO)
* Catalase
* Hemoprotein
* Peroxide
* Peroxiredoxin
* Animal heme-dependent peroxidases

## References

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1. ↑ Karthikeyan M; et al. (2005 Dec). "Induction of resistance in host against the infection of leaf blight pathogen (Alternaria palandui) in onion (Allium cepa var aggregatum)". Indian J Biochem Biophys. 42 (6): 371–7. PMID 16955738. Check date values in: `|date=` (help)CS1 maint: Explicit use of et al. (link)
2. ↑ {{cite journal| title = Amyloid-{beta} peptide binds with heme to form a peroxidase: Relationship to the cytopathologies of Alzheimer's disease | author = Hani Atamna, Kathleen Boyle | date = 21 Feb 2006 | journal = Proceedings of the National Academy of Science | volume = 103 | issue = 9 | pages = 3381 - 3386 | doi = 10.1073/pnas.0600134103}}

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Enzymes

Activity|

* Active site
* Binding site
* Catalytic triad
* Oxyanion hole
* Enzyme promiscuity
* Catalytically perfect enzyme
* Coenzyme
* Cofactor
* Enzyme catalysis

Regulation|

* Allosteric regulation
* Cooperativity
* Enzyme inhibitor
* Enzyme activator

Classification|

* EC number
* Enzyme superfamily
* Enzyme family
* List of enzymes

Kinetics|

* Enzyme kinetics
* Eadie–Hofstee diagram
* Hanes–Woolf plot
* Lineweaver–Burk plot
* Michaelis–Menten kinetics

Types|

* EC1 Oxidoreductases (list)
* EC2 Transferases (list)
* EC3 Hydrolases (list)
* EC4 Lyases (list)
* EC5 Isomerases (list)
* EC6 Ligases (list)

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Oxidoreductases: peroxidases (EC 1.11)

1.11.1.1-14|

* NADH peroxidase
* NADPH peroxidase
* Fatty-acid peroxidase
* Catalase
* Cytochrome c peroxidase
* Eosinophil peroxidase
* Glutathione peroxidase
* GPX 1
* 2
* 3
* 4
* 5
* 6
* 7
* 8
* Horseradish peroxidase
* Lactoperoxidase
* Myeloperoxidase
* Thyroid peroxidase
* Deiodinase
* Iodothyronine deiodinase
* Iodotyrosine deiodinase

1.11.1.15 (peroxiredoxin)|

* 1
* 2
* 3
* 4
* 5
* 6

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