对已公布的全基因组进行检索发现,杨树(Populus tomentosa)至少含有24个预测为可溶性环氧水解酶的基因.从中选取了7个可能的环氧水解酶基因进行克隆,通过扩增得到其中5个毛白杨(Populus tomentosa Carr)环氧水解酶基因.序列分析显示,它们与已克隆的巨大芽胞杆菌环氧水解酶的同源性仅为24％～26％.对该系列基因进行了在E.coli中的异源表达,并将得到的5个环氧水解酶(PTEH 1～5)用于缩水甘油苯基醚和对硝基苯乙烯氧化物的酶促水解反应.结果发现,其中3个重组酶具有显著的环氧水解酶活性.进一步研究表明,PTEH1和PTEH2对于缩水甘油苯基醚显示了一定的反常规的(R)-选择性,而PTEH5则优先水解(S)-构型的缩水甘油苯基醚.因此,毛白杨中环氧水解酶表现出多样性.%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.
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