固定化米曲霉氨基酰化酶拆分DL-茶氨酸

Resolution of DL-theanine with Aminoacylase of Immobilized Aspergillus oryzae Mycelia

研究固定化米曲霉Aspergillus oryzae AS3.381氨基酰化酶细胞拆分DL-茶氨酸制备L-茶氨酸的最佳工艺条件。将DL-茶氨酸乙酰化为N-乙酰-DL-茶氨酸,利用固定化米曲霉细胞立体专一性去乙酰化,可以获得L-茶氨酸,并分析固定化条件对比酶活的影响。结果显示:最适固定化条件为戊二醛浓度0.5%、交联时间2 h、温度55°C、pH8.0、底物0.2 mol/L、菌液比12 g菌体/100 mL戊二醛溶液,此时拆分率可达98%以上。菌体重复操作7批次,固定化细胞仍保留最高酶活的75%。与直接利用游离菌体转化相比,本法具有反应温度高、酶活高且稳定、能反复利用、酶活损失少等优点。

An enzymatic method for optical resolution of DL-theanine by immobilized Aspergillus oryzae AS3. 381 cell was developed in order to prepare L-theanine with lower price. By using aminoacylase of A. oryzae 3. 381 ,L-theanine was obtained via resolving N-acyl-DL-theanine which was synthesized with DL-theanine and acetic anhydride. Factors which affected the resolution were studied. The result showed that the optimum conditions were ：glutaraldehyde concentration 0. 5 %,connect time 2 h, 55 ℃,pHS. 0, substrate concentration 0. 2 mol/L and ratio of mycelia weight to glutaraldehyde volume 12 g/100 mL. The conversion rate was higher than 980%. After seven times repeated batch operation , the relative activity of immobilized cell was still 75%. The products were separated and purified on ion-exchange resin. The results indicated that resolution with immobilized mycelia had higher stability of temperature and enzymatic activity,and could be used repeatedly compared with the free pellet.