LTA4, leukotriene epoxide

The carbon sulfur bond in LTC4 is formed by the reaction of glutathione (Section 15 13) with leukotriene A4 (LTA4) LTA4 is an epoxide Sug gest a reasonable structure for LTA4... 

The cytosolic enzyme leukotriene A4 hydrolase (EC 3.3.2.6), which ster-eoselectively converts leukotriene A4 (LTA4) to leukotriene B4 [56], This enzyme catalyzes the hydrolytic cleavage of the 5,6-epoxide ring in LTA4, but, in contrast to what happens with other EHs, the product is not a vicinal diol but a 5,12-diol. As a zinc metalloenzyme, LTA4 hydrolase does not appear to be related to any other epoxide hydrolase. 

The next step is something quite new. No new C-Cbond is formed instead, the diene attacks the hydroperoxide to give an epoxide and a fully conjugated triene. The new double bond is cis this time, which is what we should expect from the conformation we have been using. This is LTA4 and all the other leukotrienes are made from this compound,... 

As part of their work in the structure proof of the natural leukotrienes, Corey s group carried out a stereospecific synthesis of 6-epi-LTA4 methyl ester as discussed earlier (Scheme 3.29). Coupling of the epoxide with the appropriately... 

In leukocytes and mast cells, 5-HPETE is converted to an epoxide, leukotriene A4 (LTA4). The subscript number 4 refers to the presence of four double bonds in the leukotriene. Three of the double bonds (7, 9, 11) are conjugated, that is, they form a triene. 

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