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FUNCTION Bifunctional zinc metalloenzyme that comprises both epoxide hydrolase (EH) and aminopeptidase activities. Acts as an epoxide hydrolase to catalyze the conversion of LTA4 to the pro-inflammatory mediator leukotriene B4 (LTB4) (PubMed:11917124, PubMed:12207002, PubMed:15078870, PubMed:18804029, PubMed:1897988, PubMed:1975494, PubMed:2244921, PubMed:2996528). Can utilize LTA5 less effectively as a substrate than LTA4, and produce LTB5 (PubMed:2996528). Also has aminopeptidase activity, with high affinity for N-terminal arginines of various synthetic tripeptides (PubMed:18804029, PubMed:20813919). In addition to its pro-inflammatory EH activity, may also counteract inflammation by its aminopeptidase activity, which inactivates by cleavage another neutrophil attractant, the tripeptide Pro-Gly-Pro (PGP), a bioactive fragment of collagen generated by the action of matrix metalloproteinase-9 (MMP9) and prolylendopeptidase (PREPL) (PubMed:20813919, PubMed:24591641). Involved also in the biosynthesis of resolvin E1 and 18S-resolvin E1 from eicosapentaenoic acid, two lipid mediators that show potent anti-inflammatory and pro-resolving actions (PubMed:21206090).CATALYTIC ACTIVITY leukotriene A4 + H2O = leukotriene B4CATALYTIC ACTIVITY (5S,6S)-epoxy-(18R)-hydroxy-(7E,9E,11Z,14Z,16E)-eicosapentaenoate + H2O = resolvin E1CATALYTIC ACTIVITY (5S,6S)-epoxy-(18S)-hydroxy-(7E,9E,11Z,14Z,16E)-eicosapentaenoate + H2O = 18S-resolvin E1CATALYTIC ACTIVITY Release of the N-terminal residue from a tripeptide.CATALYTIC ACTIVITY leukotriene A5 + H2O = leukotriene B5COFACTOR Binds 1 zinc ion per subunit.ACTIVITY REGULATION Inhibited by bestatin (PubMed:11175901). The epoxide hydrolase activity is restrained by suicide inactivation that involves binding of LTA4 to Tyr-379 (PubMed:7667299). 4-(4-benzylphenyl)thiazol-2-amine (ARM1) selectively inhibits the epoxide hydrolase activity (PubMed:24591641).BIOPHYSICOCHEMICAL PROPERTIES Lipid metabolism; leukotriene B4 biosynthesis.SUBUNIT Monomer.INTERACTION Isoform 1 and isoform 2 are expressed in monocytes, lymphocytes, neutrophils, reticulocytes, platelets and fibroblasts.PTM Phosphorylation at Ser-416 inhibits leukotriene-A4 hydrolase activity.SIMILARITY Belongs to the peptidase M1 family.
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