Lee K H, Lee P M, Siaw Y S
Department of Biotechnology, Faculty of Food Science and Biotechnology, Universiti Pertanian Malaysia, Serdang, Selangor.
J Chem Technol Biotechnol. 1993;57(1):27-32. doi: 10.1002/jctb.280570106.
Aminoacylase I (EC 3.5.1.14) encapsulated in calcium alginate beads stabilized with poly-L-lysine was used for the production of L-phenylalanine by the hydrolysis of a racemic mixture of N-acetyl-DL-phenylalanine. The immobilized aminoacylase was studied with respect to operational stability, thermal stability, effects of pH and temperature and kinetic constants. The leakage of enzyme from the stabilized beads was eliminated. The immobilized enzyme retained high biological activity. The Km and Vmax values for the stabilized beads were 11.11 mmol dm-3 and 0.076 mumol min-1 respectively. The optimum pH and temperature for the hydrolysis were 6.5 and 55 degrees C respectively. Scanning electron micrographs revealed crosslinked structures on the surface of the beads. The operational performances of the beads in a batch reaction and a packed-bed bioreactor for continuous reaction were investigated. With batch reaction, only about 5% of enzyme activity was lost within ten reaction cycles and there was no significant loss of activity over 600 h of continuous operation after equilibrium was reached, and a conversion yield of about 80% was obtained.
用聚-L-赖氨酸稳定的海藻酸钙包封的氨基酰化酶I（EC 3.5.1.14）通过水解N-乙酰-DL-苯丙氨酸的外消旋混合物来生产L-苯丙氨酸。对固定化氨基酰化酶的操作稳定性、热稳定性、pH和温度的影响以及动力学常数进行了研究。消除了酶从稳定化珠子中的泄漏。固定化酶保留了高生物活性。稳定化珠子的Km和Vmax值分别为11.11 mmol dm-3和0.076 μmol min-1。水解的最佳pH和温度分别为6.5和55℃。扫描电子显微镜照片显示珠子表面有交联结构。研究了珠子在间歇反应和填充床生物反应器中进行连续反应的操作性能。在间歇反应中，在十个反应周期内仅约5%的酶活性丧失，达到平衡后连续操作600小时以上活性没有显著损失，并且获得了约80%的转化率。
