This MedLibrary.org supplementary page on Glutathione peroxidase is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
 |
|
|
glutathione peroxidase 1
|
|
| Identifiers | |
| Symbol | GPX1 |
| Entrez | 2876 |
| HUGO | 4553 |
| OMIM | 138320 |
| RefSeq | NM_000581 |
| UniProt | P07203 |
| Other data | |
| EC number | 1.11.1.9 |
| Locus | Chr. 3 p21.3 |
|
glutathione peroxidase 3 (plasma)
|
|
| Identifiers | |
| Symbol | GPX3 |
| Entrez | 2878 |
| HUGO | 4555 |
| OMIM | 138321 |
| RefSeq | NM_002084 |
| UniProt | P22352 |
| Other data | |
| EC number | 1.11.1.9 |
| Locus | Chr. 5 q23 |
|
glutathione peroxidase 5 (epididymal androgen-related protein)
|
|
| Identifiers | |
| Symbol | GPX5 |
| Entrez | 2880 |
| HUGO | 4557 |
| OMIM | 603435 |
| RefSeq | NM_001509 |
| UniProt | O75715 |
| Other data | |
| EC number | 1.11.1.9 |
| Locus | Chr. 6 p21.32 |
|
glutathione peroxidase 6 (olfactory)
|
|
| Identifiers | |
| Symbol | GPX6 |
| Entrez | 257202 |
| HUGO | 4558 |
| OMIM | 607913 |
| RefSeq | NM_182701 |
| UniProt | P59796 |
| Other data | |
| EC number | 1.11.1.9 |
| Locus | Chr. 6 p21 |
Glutathione peroxidase (PDB 1GP1, EC 1.11.1.9) is the general name of an enzyme family with peroxidase activity whose main biological role is to protect the organism from oxidative damage. The biochemical function of glutathione peroxidase is to reduce lipid hydroperoxides to their corresponding alcohols and to reduce free hydrogen peroxide to water.
Contents |
Isozymes
There are several isozymes encoded by different genes, which vary in celullar location and substrate specificity. Glutathione peroxidase 1 is the most abundant version, found in the cytoplasm of nearly all mammalian tissues, whose preferred substrate is hydrogen peroxide.
Reaction
An example reaction that glutathione peroxidase catalyzes is:
- 2GSH + H2O2 → GS–SG + 2H2O,
where GSH represents reduced monomeric glutathione, and GS–SG represents glutathione disulfide.
Glutathione reductase then reduces the oxidized glutathione to complete the cycle:
- GS–SG + NADPH + H+ → 2 GSH + NADP+.
Structure
Glutathione peroxidase is a selenium-containing tetrameric glycoprotein, that is, a molecule with four selenocysteine amino acid residues. As the integrity of the cellular and subcellular membranes depends heavily on glutathione peroxidase, the antioxidative protective system of glutathione peroxidase itself depends heavily on the presence of selenium.
GP reaction mechanism
The mechanism is at the Selenocystein site, which is in a Se(-) form as resting state. This is oxidized by the peroxide to SeOH which is then trapped by a GSH molecule to Se-SG and by another GSH molecule to Se(-) again, releasing a GS-SG by-product.
GP in other animals
Mice genetically engineered to lack glutathione peroxidase 1 (Gpx1 knockout mice) are phenotypically normal, indicating that this enzyme is not critical for life.
However, glutathione peroxidase 4 knockout (Gpx4 knockout) mice die during early embryonic development.
There is some evidence that reduced levels of glutathione peroxidase 4 can increase life expectancy in mice.[1]
The bovine erythrocyte enzyme has a molecular weight of 84 kDa.
History
Glutathione peroxidase was discovered in 1957 by Gordon C. Mills. [2]
References
- ^ Ran Q, Liang H, Ikeno Y, et al (2007). "Reduction in glutathione peroxidase 4 increases life span through increased sensitivity to apoptosis". J. Gerontol. A Biol. Sci. Med. Sci. 62 (9): 932–42. PMID 17895430.
- ^ Mills, G. Journal of Biological Chemistry 229:189-97.1957.
See also
|
||||||||
 |
This EC 1.11 enzyme-related article is a stub. You can help Wikipedia by expanding it. |
Wikipedia content modification information:
- This page was last modified on 16 September 2008, at 12:27.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Glutathione peroxidase".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.