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MetaCyc Enzyme: glutathione peroxidase 1

Gene: GPX1 Accession Number: G-7533 (MetaCyc)

Synonyms: GPX-1

Species: Homo sapiens

Subunit composition of glutathione peroxidase 1 = [GPX1]4
         glutathione peroxidase 1 subunit = GPX1

Summary:
Glutathione peroxidases (GPxs) are a family of enzymes that scavenge peroxides generated in cells. Some isozymes have selenium-dependent glutathione peroxidase activity and contain selenocysteine encoded by a TGA codon, while others do not contain selenocysteine [Arthur00a]. There are four major selenium dependent GPx isozymes in mammalian tissues; classical GPx (GPx-1; E.C. 1.11.1.9), gastrointestinal GPx (GPx-2), plasma GPx (GPx-3), and phospholipid GPx (GPx-4; E.C. 1.11.1.12). GPx-1, 2, and 3 act as homotetramers, while GPx-4 as a monomer [Arthur00a].

In addition to the selenium-containing GPXs and the proteins which contain cysteine and have similar structures to the GPXs, there are many selenium independent GPX activities in mammalian systems. These activities are mainly associated with the glutathione-S-transferase family of enzymes, whose activity is directed mainly towards organic hydroperoxides, and not hydrogen peroxide.

Gene Citations: [Sukenaga87]

Molecular Weight of Polypeptide: 21.899 kD (from nucleotide sequence), 23 kD (experimental) [Rey94 ]

Molecular Weight of Multimer: 92 kD (experimental) [Rey94]

pI: 5.1 [Rey94]

Unification Links: ArrayExpress:P07203 , ModBase:P07203 , PhosphoSite:P07203 , PhylomeDB:P07203 , Pride:P07203 , Protein Model Portal:P07203 , SMR:P07203 , String:9606.ENSP00000407375 , Swiss-Model:P07203 , UniProt:P07203

Relationship Links: Entrez-Nucleotide:PART-OF:Y00433 , InterPro:IN-FAMILY:IPR000889 , InterPro:IN-FAMILY:IPR012336 , Panther:IN-FAMILY:PTHR11592 , PDB:Structure:2F8A , Pfam:IN-FAMILY:PF00255 , Prints:IN-FAMILY:PR01011 , Prosite:IN-FAMILY:PS00460 , Prosite:IN-FAMILY:PS00763 , Prosite:IN-FAMILY:PS51355

Gene-Reaction Schematic: ?

MultiFun Terms: cell processes protection detoxification


Enzymatic reaction of: glutathione peroxidase

Synonyms: classical GPX

EC Number: 1.11.1.9

hydrogen peroxide + 2 glutathione <=> glutathione disulfide + 2 H2O

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

In Pathways: glutathione redox reactions I , reactive oxygen species degradation (mammalian)

Summary:
Mills first described GPX activity in 1957 [Mills57], and predicted it to be responsible for the protection of red blood cells against haemolysis by oxidation. The enzyme, now called GPX-1, was originally called glutathione peroxidase, and also classical GPX, cytosolic or cellular GPX. GPX-1 can metabolize hydrogen peroxide and a range of organic peroxides, including cholesterol and long-chain fatty acid peroxides. However, unless accompanied by phospholipase A2 activity to release the fatty acids, GPX-1 cannot metabolize fatty acid hydroperoxides in phospholipids [Grossmann83]. GPX-1 can interact with a wide range of organic hydroperoxides as well as hydrogen peroxide. Despite this range of peroxide substrates, it is very specific for glutathione as reducing substrate [Arthur00a].

Activators (Unknown Mechanism): Se0 [Flohe73]

pH(opt): 8.5 [Rey94]


References

Arthur00a: Arthur, J. R. (2000). "The glutathione peroxidases." Cell. Mol. Life Sci. 57:1825-1835.

Flohe71: Flohe L, Eisele B, Wendel A (1971). "[Glutathion peroxidase. I. Isolation and determinations of molecular weight]." Hoppe Seylers Z Physiol Chem 352(2);151-8. PMID: 5549561

Flohe73: Flohe L, Gunzler WA, Schock HH (1973). "Glutathione peroxidase: a selenoenzyme." FEBS Lett 32(1);132-4. PMID: 4736708

Grossmann83: Grossmann A, Wendel A (1983). "Non-reactivity of the selenoenzyme glutathione peroxidase with enzymatically hydroperoxidized phospholipids." Eur J Biochem 135(3);549-52. PMID: 6413205

Mills57: Mills, G. C. (1957). "Hemoglobin catabolism. I. Glutathione peroxidase, an erythrocyte enzyme which protects hemoglobin from oxidative breakdown." J Biol Chem 229(1);189-97. PMID: 13491573

Rey94: Rey C, Vericel E, Nemoz G, Chen W, Chapuy P, Lagarde M (1994). "Purification and characterization of glutathione peroxidase from human blood platelets. Age-related changes in the enzyme." Biochim Biophys Acta 1226(2);219-24. PMID: 8204670

Sukenaga87: Sukenaga Y, Ishida K, Takeda T, Takagi K (1987). "cDNA sequence coding for human glutathione peroxidase." Nucleic Acids Res 15(17);7178. PMID: 3658677


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Mon Dec 22, 2014, biocyc14.