以琼脂粉为基质制备金属螯合载体,并用于固定重组腈水解酶.研究发现:制备金属螯合载体最合适的金属离子为Zn2+.当Zn2+离子浓度0.3 mol/L、给酶量15.6 mg/g、固定化pH 8.0、固定化温度40℃时,制得的固定化酶活性最高.固定化酶最适反应温度为50℃、最适反应pH为7.0.当扁桃腈浓度为10 mmol/L、反应1 h时,固定化酶最大产率为0.041 mmol/(g·h)；在反应12 h时,产物e.e.值可达到99％以上.固定化酶重复使用8次以后,酶活力仍保持在45％.%Metal chelating carrier with agar as the matrix was prepared and employed to recombinant nitrilase immobilization. Zn2+ was selected as suitable chelator. When the concentration of Zn2+ was 0. 3 mol/L and enzyme load was 15. 6 mg/g, the immobilized nitrilase showed a high activity at pH 8. 0 and 40 ℃. The maximum conversion of mandelonitrile to (R)-(-)-mandelic acid by the immobilized nitrilase was observed at pH 7. 0 and 50 ℃. When the substrate concentration was 10 mmol/L and the reaction time was 1 h, the conversion reached 70% with 99% e. e. after 12 h. After 8 recycles in batch operation, the activity remained at 45 % .
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