Gao Yu, Liu Zhongmei, Liu Ke, Zhou Zhemin, Cui Wenjing
College of Bioengineering, Jiangnan University, Wuxi 214122, Jiangsu, China.
Sheng Wu Gong Cheng Xue Bao. 2017 May 25;33(5):875-879. doi: 10.13345/j.cjb.160416.
Enzymatic synthesis is an important way to produce β-alanine, but the biological method is expensive generally because of the high price of substrate. In this paper, a two-step enzymatic cascade system was developed, combining L-aspartase from Escherichia coli DH5α and L-aspartate α-decarboxylase from Corynebacterium glutamicum. This system catalyzes Fumarate and ammonia to β-alanine. The optimal ratio of AspA and PanD was 1:80 (W/W), and the concentration of AspA was 10 μg/mL, at 37 ℃ and pH 7.0. When the concentration of Fumarate was 100 mmol/L, the reaction reached its equilibrium after 8 h, and the yield of β-alanine was 90 mmol/L (7 g/L). The yield of β-alanine can reach 126 mmol/L (9.8 g/L) when the concentration of Fumarate increased to 200 mmol/L. Extending reaction time, the conversion rate did not change obviously. Using this two-step enzymatic cascade system, β-alanine from cheaper substrate Fumarate can be obtained.
酶法合成是生产β-丙氨酸的重要途径，但由于底物价格高昂，生物法通常成本较高。本文构建了一种两步酶级联系统，该系统结合了来自大肠杆菌DH5α的L-天冬氨酸酶和来自谷氨酸棒杆菌的L-天冬氨酸α-脱羧酶。此系统催化富马酸和氨生成β-丙氨酸。在37℃和pH 7.0条件下，AspA和PanD的最佳比例为1:80（W/W），AspA的浓度为10μg/mL。当富马酸浓度为100mmol/L时，反应8小时后达到平衡，β-丙氨酸产量为90mmol/L（7g/L）。当富马酸浓度增至200mmol/L时，β-丙氨酸产量可达126mmol/L（9.8g/L）。延长反应时间，转化率无明显变化。利用该两步酶级联系统，可从更廉价的底物富马酸中获得β-丙氨酸。
