In enzymology, a phospholipid-hydroperoxide glutathione peroxidase () is an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

that

catalyzes Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycl ...

the

chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and break ...

:2 glutathione + a lipid hydroperoxide

\rightleftharpoons

glutathione disulfide + lipid + 2 H₂O Thus, the two substrates of this enzyme are

glutathione Glutathione (GSH, ) is an antioxidant in plants, animals, fungi, and some bacteria and archaea. Glutathione is capable of preventing damage to important cellular components caused by sources such as reactive oxygen species, free radicals, pe ...

and lipid hydroperoxide, whereas its 3 products are glutathione disulfide,

lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids incl ...

, and H₂O. This enzyme belongs to the family of

oxidoreductase In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor. This group of enzymes usually ...

s, to be specific those acting on a peroxide as acceptor (peroxidases). The

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivial ...

of this enzyme class is glutathione:lipid-hydroperoxide oxidoreductase. Other names in common use include peroxidation-inhibiting protein, PHGPX, peroxidation-inhibiting protein: peroxidase, glutathione, (phospholipid hydroperoxide-reducing), phospholipid hydroperoxide glutathione peroxidase, hydroperoxide glutathione peroxidase, or glutathione peroxidase 4 (

GPX4 Glutathione peroxidase 4, also known as GPX4, is an enzyme that in humans is encoded by the ''GPX4'' gene. GPX4 is a phospholipid hydroperoxidase that protects cells against membrane lipid peroxidation. Function The antioxidant enzyme gluta ...

). This enzyme participates in

glutathione metabolism Glutathione (GSH, ) is an antioxidant in plants, animals, fungi, and some bacteria and archaea. Glutathione is capable of preventing damage to important cellular components caused by sources such as reactive oxygen species, free radicals, pe ...

Structural studies

As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes and .

References

* EC 1.11.1 Enzymes of known structure {{1.11-enzyme-stub