CHARACTERIZATION OF A CATABOLIC EPOXIDE HYDROLASE FROM A CORYNEBACTERIUM SP

The epoxide hydrolase (EH) from Corynebacterium sp. C12, which grows o n cyclohexene oxide as sole carbon source, has been purified to homoge neity in two steps, involving anion exchange followed by hydrophobic-i nteraction chromatography. The purified enzyme is multimeric (probably tetrameric) with a subunit size of 32 140 Da. The gene encoding Coryn ebacterium EH was located on a 3.5-kb BamHI fragment of C12 chromosoma l DNA using a DNA probe generated by PCR using degenerate primers base d on the N-terminal and an internal amino acid sequence. Sequencing an d database comparison of the predicted amino acid sequence of Coryneba cterium EH shows that it is similar to mammalian and plant soluble EH, and the recently published sequence of epichlorohydrin EH from Agroba cterium radiobacter AD1 [Rink, R., Fennema, M., Smids, M., Dehmel, U. & Janssen, D. B. (1997) J. Biol. Chem. 272, 14 650-14 657], particular ly around the catalytic site. All of these proteins belong to the alph a/beta-hydrolase-fold family of enzymes. Similarity to the mammalian m icrosomal EH is weaker.