Metabolism of leukotriene E4 by rat tissues: formation of N-acetyl leukotriene E4.

Leukotriene E4 was incubated with subcellular fractions from rat liver homogenates. A product identified as 5-hydroxy-6-S-(2-acetamido-3-thiopropionyl)-7,9-trans-11,14- cis-eicosatetraenoic acid (N-acetyl leukotriene E4) was formed. Enzymes catalyzing the reaction were associated with particulate fractions sedimenting between 600 and 8500 g and 20,000 and 105,000 g. Acetyl coenzyme A served as the donor of the acetyl group. N-Acetyl leukotriene E4 was also formed by the 105,000g sediment fractions from kidney, spleen, skin, and lung. The myotropic activity of N-acetyl leukotriene E4 on isolated guinea pig ileum was reduced over 100-fold compared to that of leukotriene D4.