微生物发酵法产环氧化物水解酶的研究

A study of epoxide hydrolase produced by microbial fermentation

从土壤中筛选出一株能将模型底物缩水甘油苯基醚水解为3-苯氧基-1，2-一丙二醇的环氧化物水解酶的芽孢杆菌H-14-1．此茵培养的最佳碳源为1％的葡萄糖，最佳的氮源为1％的NH4Cl和1％牛肉膏，培养基的初始pH为6．5，培养的最佳温度和时问是30℃下培养36h，低浓度底物缩水甘油苯基醚对该酶具有诱导作用，同时培养基中金属Cu外离子对产酶有促进作用．酶学性质的试验表明，该酶的最适反应温度为35℃，最适pH为7．5，40℃以下酶具有较好的热稳定性，pH6．5～8．0范围内酶的稳定性较佳，Mg^2＋和Ca^2＋离子对酶的活性有促进作用．

A bacterial strain （H-14-1） was isolated from soil and identified as Bacillus Megaterium. The strain showed an activity of epoxide hydrolase that could catalyze the asymmetric hydrolysis of phenyl glycidyl ether. The fermentation conditions for this strain were optimized. With 1% glucose as carbon source, 1% NH4Cl and 1% beef extract as nitrogen source, initial pH 6.5, and cultivated at 30℃, this strain grew well and showed high epoxide hydrolase activity. In addition, the Cu^2＋ could promote the production of epoxide hydrolase. The epoxide hydrolase has been purified. A study on the catalytic performance of the epoxide hydrolase showed that the maximum activity of this enzyme was obtained at 35℃ and pH 6.5, and it was quite stable at pH 6.5-8.0 and at temperatures bellow 40℃. The Ca^2＋ and Mg^2＋ could promote the activity of the epoxide hydrolase.