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The systematic name of this enzyme class is leukotriene-C4 glutathione-lyase (leukotriene-A4-forming). Other names in common use include leukotriene C4 synthetase, LTC4 synthase, LTC4 synthetase, leukotriene A4:glutathione S-leukotrienyltransferase, (7E,9E,11Z,14Z)-(5S,6R)-5,6-epoxyicosa-7,9,11,14-, tetraenoate:glutathione leukotriene-transferase, (epoxide-ring-opening), (7E,9E,11Z,14Z)-(5S,6R)-6-(glutathion-S-yl)-5-hydroxyicosa-, and 7,9,11,14-tetraenoate glutathione-lyase (epoxide-forming). This enzyme participates in arachidonic acid metabolism.

Mechanism of reaction
The EC number of Leukotriene-C4 synthase is 4.4.1.20. This number signifies that the enzyme belongs to the family of lyases, specifically the class of carbon-sulfur lyases. These enzymes catalyze non-hydrolytic additions or removals of groups from substrates. Bonds such as those of carbon bound to another carbon, nitrogen, oxygen, or sulfur could be cleaved.

In enzymology, a leukotriene-C4 synthase is an enzyme that catalyzes the chemical reaction
 * leukotriene C4 $$\rightleftharpoons$$ leukotriene A4 + glutathione

Hence, this enzyme has one substrate, leukotriene C4, and two products, leukotriene A4 and glutathione.

Leukotriene (LT) C4 synthase is a trimeric integral membrane protein and conjugates LTA4, an epoxide intermediate, to glutathione (GSH) to form a pro-inflammatory mediator LTC4. This enzyme is part of the MAPEG (Membrane Associated Proteins in Eicosanoid and Glutathione metabolism) transmembrane proteins. This enzyme catalyzes the first step of the biosynthesis of cysteinyl leukotrienes which are derived from arachidonic acid. A trimer of LTC4 synthase is found on the outer nuclear membrane and endoplasmic reticulum where it complexes with 5-Lipoxygenase-activating protein.

This enzyme is found in both human and mouse and their gene locations have been identified. The family of MAPEG is comprised of proteins involved with the production of leukotrienes. Leukotrienes have been found to play a role in mediating anaphylaxis and inflammatory conditions like human bronchial asthma. Additionally, the pro-inflammatory factor, LTC4S, acts on plasma membrane cysteinyl leukotriene receptors and it is a cytosolic second messenger that can activate store-independent LTC4-regulated calcium channels encoded by Orai1/Orai3 heteromultimers in vascular smooth muscle cells. The role of LTC4S, however, remains unclear in neointima formation.

Leukotriene C4 and its metabolites LTD4 and LTE4 are the components of the slow-reacting substances of anaphylaxis which are lipid mediators of both smooth muscle constriction and inflammation, specifically with bronchial asthma. LTC4S, a crucial enzyme for the biosynthesis of LTC4 is a 18kDa integral nuclear membrane protein. It belongs to the membrane-associated proteins in eicosanoid and glutathione metabolism.

Crystal structures
LTC4S monomer has 4 transmembrane alpha-helices and it forms a trimeric integral membrane protein. Glutathione is in a U-shaped conformation and this binding is stabilized by a loop structure at the top of the interface between the adjacent monomers. The enzyme-substrate complex shows the active site forms a horseshoe-shaped structure on GSH. This positions the thiol group for activation by arginine at the membrane-enzyme interface. The structure also shows the omega-end of the lipophillic co-substrate at one end of the hydrophobic cleft serving to align the epoxide at the thiol of glutathione. This information suggests the observed activation of GSH may be found in the family of homologous proteins frequently and therefore have an important role in inflammatory and detoxification responses.

Structural studies
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes, , and.