Abstract: The genome of Populus tomentosa was the first to be reported in trees. Based on the mining results of the database, a gene pool encoding 24 potential soluble epoxide hydrolases was proposed. In which, 7 genes were selected in this study, and 5 genes were successfully cloned and sequenced. Sequence analysis showed that the cloned epoxide hydrolases had merely 24%–26% similarity to the newly cloned Bacillus megaterium epoxide hydrolase. Then the 5 genes were heterogeneously expressed in E. coli and used for hydrolytic reactions of two model substrates, phenyl glycidyl ether and p-nitrostyrene oxide. Epoxide hydrolysis activity was detected in 3 recombinant epoxide hydrolases, in which PTEH1 and PTEH2 showed (R)-selectivity in hydrolysis of phenyl glycidyl ether, while PTEH5 preferred to hydrolyze (S)-phenyl glycidyl ether. This work proves the diversity of epoxide hydrolases from P. tomentosa.

Key words: Populus tomentosa, epoxide hydrolase, heterogeneous expression, phenyl glycidyl ether, p-nitrostyrene oxide, catalytic resolution