| 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 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 D4 dipeptidase | <enzyme> Converts leukotriene d4 to leukotriene e4 Registry number: EC 3.4.13.- Synonym: ld4 dipeptidase (26 Jun 1999) |
| 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) |
| 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) |
| leukotrienes | A family of biologically active compounds derived from arachidonic acid by oxidative metabolism through the 5-lipoxygenase pathway. They participate in host defense reactions and pathophysiological conditions such as immediate hypersensitivity and inflammation. They have potent actions on many essential organs and systems, including the cardiovascular, pulmonary, and central nervous system as well as the gastrointestinal tract and the immune system. (12 Dec 1998) |
| Leukovirus | A former genus composed of the RNA tumour viruses now included in the family Retroviridae. (05 Mar 2000) |
| leupeptin | A peptide (N-acetylleucylleucylarginyl) from Streptomyces species that inhibits cathepsin B, papain, trypsin, plasmin, and cathepsin D. (05 Mar 2000) |
| leupeptin acid reductase | <enzyme> Converts leupeptin acid (acetyl-l-leu-l-leu-l-arg) into leupeptin (acetyl-l-leu-l-leu-l-arginal); requires ATP and NADPH Registry number: EC 1.2.1.- (26 Jun 1999) |