Metabolism and excretion of cysteinyl-leukotrienes.
In vitro and in vivo experiments have demonstrated that a major pathway of metabolism of the glutathione containing leukotrienes involves modifications of the tripeptide substituent. The metabolic alterations are initiated by elimination of the N-terminal gamma-glutamyl residue, catalyzed by the enzyme gamma-glutamyl transferase. This reaction is followed by hydrolysis of the remaining peptide bond resulting in elimination of the C-terminal glycine residue. The enzyme catalyzing the latter reaction is a membrane bound dipeptidase which occurs in kidney and other tissues. The product formed by these reactions, leukotriene E4, has been tentatively identified as a urinary metabolite in man following intravenous administration of leukotriene C4. In rats, two major fecal metabolites of leukotriene C4 were characterized as having the structures N-acetyl leukotriene E4 and N-acetyl 11-trans leukotriene E4. These compounds are formed from leukotriene E4 and 11-trans leukotriene E4 in reactions with acetyl coenzyme A. A membrane bound enzyme, present in liver, kidney and other tissues, catalyzes these reactions.
D000818:Animals; D001693:Biological Transport, Active; D000882:Haplorhini; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D013189:SRS-A / Q000031:analogs & derivatives / Q000378:metabolism* / Q000652:urine
D013189:SRS-A; C028724:leukotriene C-3