Epoxide hydrolases catalyse the hydrolysis of epoxides to corresponding diols, which is important in detoxification, synthesis of signal molecules, or metabolism. Limonene-1,2- epoxide hydrolase (LEH) differs from many other epoxide hydrolases in its structure and its novel one-step catalytic mechanism. Its main fold consists of a six-stranded mixed beta-sheet, with three N-terminal alpha helices packed to one side to create a pocket that extends into the protein core. A fourth helix lies in such a way that it acts as a rim to this pocket. Although mainly lined by hydrophobic residues, this pocket features a cluster of polar groups that lie at its deepest point and constitute the enzyme's active site [1].

1: Structure of Rhodococcus erythropolis limonene-1,2-epoxide hydrolase reveals a novel active site. Arand M, Hallberg BM, Zou J, Bergfors T, Oesch F, van der Werf MJ, de Bont JA, Jones TA, Mowbray SL; EMBO J 2003;22:2583-2592. PMID:12773375