Reaction: an epoxide + H2O = a glycol
Other name(s): epoxide hydrase (ambiguous); epoxide hydratase (ambiguous); arene-oxide hydratase (ambiguous); aryl epoxide hydrase (ambiguous); trans-stilbene oxide hydrolase; sEH; cytosolic epoxide hydrolase
Systematic name: epoxide hydrolase
Comments: Catalyses the hydrolysis of trans-substituted epoxides, such as trans-stilbene oxide, as well as various aliphatic epoxides derived from fatty-acid metabolism [7]. It is involved in the metabolism of arachidonic epoxides (epoxyicosatrienoic acids; EETs) and linoleic acid epoxides. The EETs, which are endogenous chemical mediators, act at the vascular, renal and cardiac levels to regulate blood pressure [4,5]. The enzyme from mammals is a bifunctional enzyme: the C-terminal domain exhibits epoxide-hydrolase activity and the N-terminal domain has the activity of EC 3.1.3.76, lipid-phosphate phosphatase [1,2]. Like EC 3.3.2.9, microsomal epoxide hydrolase, it is probable that the reaction involves the formation of an hydroxyalkyl—enzyme intermediate [4,6]. The enzyme can also use leukotriene A4, the substrate of EC 3.3.2.6, leukotriene-A4 hydrolase, but it forms 5,6-dihydroxy-7,9,11,14-eicosatetraenoic acid rather than leukotriene B4 as the product [9,10]. In vertebrates, five epoxide-hydrolase enzymes have been identified to date: EC 3.3.2.6 (leukotriene-A4 hydrolase), EC 3.3.2.7 (hepoxilin-epoxide hydrolase), EC 3.3.2.9 (microsomal epoxide hydrolase), EC 3.3.2.10 (soluble epoxide hydrolase) and EC 3.3.2.11 (cholesterol 5,6-oxide hydrolase) [7].
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9048-63-9
References:
1. Newman, J.W., Morisseau, C., Harris, T.R. and Hammock, B.D. The soluble epoxide hydrolase encoded by EPXH2 is a bifunctional enzyme with novel lipid phosphate phosphatase activity. Proc. Natl. Acad. Sci. USA 100 (2003) 1558-1563. [PMID: 12574510]
2. Cronin, A., Mowbray, S., Durk, H., Homburg, S., Fleming, I., Fisslthaler, B., Oesch, F. and Arand, M. The N-terminal domain of mammalian soluble epoxide hydrolase is a phosphatase. Proc. Natl. Acad. Sci. USA 100 (2003) 1552-1557. [PMID: 12574508]
3. Oesch, F. Mammalian epoxide hydrases: inducible enzymes catalysing the inactivation of carcinogenic and cytotoxic metabolites derived from aromatic and olefinic compounds. Xenobiotica 3 (1973) 305-340. [PMID: 4584115]
4. Morisseau, C. and Hammock, B.D. Epoxide hydrolases: mechanisms, inhibitor designs, and biological roles. Annu. Rev. Pharmacol. Toxicol. 45 (2005) 311-333. [PMID: 15822179]
5. Yu, Z., Xu, F., Huse, L.M., Morisseau, C., Draper, A.J., Newman, J.W., Parker, C., Graham, L., Engler, M.M., Hammock, B.D., Zeldin, D.C. and Kroetz, D.L. Soluble epoxide hydrolase regulates hydrolysis of vasoactive epoxyeicosatrienoic acids. Circ. Res. 87 (2000) 992-998. [PMID: 11090543]
6. Lacourciere, G.M. and Armstrong, R.N. The catalytic mechanism of microsomal epoxide hydrolase involves an ester intermediate. J. Am. Chem. Soc. 115 (1993) 10466-10456.
7. Fretland, A.J. and Omiecinski, C.J. Epoxide hydrolases: biochemistry and molecular biology. Chem. Biol. Interact. 129 (2000) 41-59. [PMID: 11154734]
8. Zeldin, D.C., Wei, S., Falck, J.R., Hammock, B.D., Snapper, J.R. and Capdevila, J.H. Metabolism of epoxyeicosatrienoic acids by cytosolic epoxide hydrolase: substrate structural determinants of asymmetric catalysis. Arch. Biochem. Biophys. 316 (1995) 443-451. [PMID: 7840649]
9. Haeggström, J., Meijer, J. and Radmark, O. Leukotriene A4. Enzymatic conversion into 5,6-dihydroxy-7,9,11,14-eicosatetraenoic acid by mouse liver cytosolic epoxide hydrolase. J. Biol. Chem. 261 (1986) 6332-6337. [PMID: 3009453]
10. Newman, J.W., Morisseau, C. and Hammock, B.D. Epoxide hydrolases: their roles and interactions with lipid metabolism. Prog. Lipid Res. 44 (2005) 1-51. [PMID: 15748653]