| leukotriene | Any of a group of hormonesderived from arachidonate (arachidonic acid).They are thought to mediate the allergic response that causes lungconstriction and muscle contraction in asthma. (09 Oct 1997) |
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| leukotriene a4 | (2s-(2 alpha,3 beta(1e,3e,5z,8z)))-3-(1,3,5,8-tetradecatetraenyl)oxiranebutanoic acid. An unstable allylic epoxide, formed from the immediate precursor 5-hpete via the stereospecific removal of a proton at c-10 and dehydration. Its biological actions are determined primarily by its metabolites, i.e., leukotriene b4 and cysteinyl-leukotrienes. Alternatively, leukotriene a4 is converted into leukotriene c4 by glutathione-s-transferase or into 5,6-di-hete by the epoxide-hydrolase. (12 Dec 1998) |
| leukotriene A4 hydrolase | <enzyme> Catalyses hydrolysis of leukotriene a4 to leukotriene b4; mw 68,000-70,000 Registry number: EC 3.3.2.- Synonym: leukotriene a4 aminopeptidase (26 Jun 1999) |
| leukotriene b4 | <chemical> (s-(r*,s*-(e,z,e,z)))-5,12-dihydroxy-6,8,10,14-eicosatetraenoic acid. The major metabolite in neutrophil polymorphonuclear leukocytes. It stimulates polymorphonuclear cell function (degranulation, formation of oxygen-centreed free radicals, arachidonic acid release, and metabolism). Chemical name: 6,8,10,14-Eicosatetraenoic acid, 5,12-dihydroxy-, (S-(R*,S*-(E,Z,E,Z)))- (12 Dec 1998) |
| leukotriene B4 12-hydroxydehydrogenase | <enzyme> Catalyses the oxidation of leukotriene b4 to 12-oxoleukotriene b4 Registry number: EC 1.1.1.- Synonym: ltb4 12-hydroxydehydrogenase, ltb(4) 12-hydroxydehydrogenase (26 Jun 1999) |
| leukotriene B4 6-isomerase | <enzyme> From rat kidney homogenates Registry number: EC 5.2.- (26 Jun 1999) |
| leukotriene B4 reductase | <enzyme> Converts leukotriene b4 (5s,12r-dihydroxyeicosoletra-6,8,10,14-enoic acid) to dihydro ltb4 (5s,12r-10,11-dihydroeicosatri-6,8,14-enoic acid), requires NADPH, ca and mg Registry number: EC 1.3.1.- (26 Jun 1999) |
| leukotriene c4 | <chemical> (r-(r*,s*-(e,e,z,z))))-n-(s-(1-(4-carboxy-1-hydroxybutyl)-2,4,6,9-pentadecatetraenyl)-n-l-gamma-glutamyl-l-cysteinyl)glycine. The conjugation product of leukotriene a4 and glutathione. It is the major arachidonic acid metabolite in macrophages and human mast cells as well as in antigen-sensitised lung tissue. It stimulates mucus secretion in the lung, and produces contractions of nonvascular and some vascular smooth muscle. Chemical name: Glycine, N-(S-(1-(4-carboxy-1-hydroxybutyl)-2,4,6,9-pentadecatetraenyl)-N-L-gamma-glutamyl-L-cysteinyl)-, (R-(R*,S*-(E,E,Z,Z)))- (12 Dec 1998) |
| leukotriene-C4 synthase | <enzyme> From particulate fraction of rat basophil leukaemia homogenates; not sensitive to inhibitors of most soluble glutathione s-transferases Registry number: EC 2.5.1.37 Synonym: leukotriene c synthase, leukotriene a4-glutathione s-leukotrienyltransferase, leukotriene c4 synthetase, glutathione s-transferase II, gst-ii (26 Jun 1999) |
| leukotriene d4 | <chemical> (r-(r*,s*-(e,e,z,z)))-n-(s-(1-(4-carboxy-1-hydroxybutyl)-2,4,6,9-pentadecatetraenyl)-l-cysteinyl)glycine. One of the biologically active principles of srs-a. It is generated from leukotriene c4 after partial hydrolysis of the peptide chain, i.e., cleavage of the gamma-glutamyl portion. Its biological actions include stimulation of vascular and nonvascular smooth muscle, and increases in vascular permeability. Chemical name: Glycine, N-(S-(1-(4-carboxy-1-hydroxybutyl)-2,4,6,9-pentadecatetraenyl)-L-cysteinyl)-, (R-(R*,S*-(E,E,Z,Z)))- (12 Dec 1998) |
| leukotriene e4 | <chemical> (5s-(5r*,6s*(s*),7e,9e,11z,14z))-6-((2-amino-2-carboxyethyl)thio)-5-hydroxy-7,9,11,14-eicosatetraenoic acid. A biologically active principle of srs-a that is formed from leukotriene d4 via a peptidase reaction that removes the glycine residue. The biological actions of lte4 are similar to ltc4 and ltd4. Chemical name: 7,9,11,14-Eicosatetraenoic acid, 6-((2-amino-2-carboxyethyl)thio)-5-hydroxy-, (5S-(5R*,6S*(S*),7E,9E,11Z,14Z))- (12 Dec 1998) |