Only the C-terminal part of the protein (from aa 226) has the alpha/beta hydrolase fold. The N terminal part is alpha/beta Rossmann-fold related to L-2-Haloacid dehalogenase, HAD
Title: Detoxification of environmental mutagens and carcinogens: structure, mechanism, and evolution of liver epoxide hydrolase Argiriadi MA, Morisseau C, Hammock BD, Christianson DW Ref: Proceedings of the National Academy of Sciences of the United States of America, 96:10637, 1999 : PubMed
The crystal structure of recombinant murine liver cytosolic epoxide hydrolase (EC 3.3.2.3) has been determined at 2.8-A resolution. The binding of a nanomolar affinity inhibitor confirms the active site location in the C-terminal domain; this domain is similar to that of haloalkane dehalogenase and shares the alpha/beta hydrolase fold. A structure-based mechanism is proposed that illuminates the unique chemical strategy for the activation of endogenous and man-made epoxide substrates for hydrolysis and detoxification. Surprisingly, a vestigial active site is found in the N-terminal domain similar to that of another enzyme of halocarbon metabolism, haloacid dehalogenase. Although the vestigial active site does not participate in epoxide hydrolysis, the vestigial domain plays a critical structural role by stabilizing the dimer in a distinctive domain-swapped architecture. Given the genetic and structural relationships among these enzymes of xenobiotic metabolism, a structure-based evolutionary sequence is postulated.
        
Representative scheme of Epoxide_hydrolase structure and an image from PDBsum server
no Image
Databases
PDB-Sum
1EK1 Previously Class, Architecture, Topology and Homologous superfamily - PDB-Sum server
FSSP
1EK1Fold classification based on Structure-Structure alignment of Proteins - FSSP server