Zhang Yingkang, Cheng Ting, Zhao Feiyang, Yi Yanqin, Li Qingqing, Lu Zhenhua, Wu Mianbin, Wang Tao, Liu Xiaohuan
School of Biological Science, Jining Medical University, Rizhao 276800, Shandong, China.
College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310000, Zhejiang, China.
Sheng Wu Gong Cheng Xue Bao. 2023 Mar 25;39(3):1131-1141. doi: 10.13345/j.cjb.220848.
The α-amino acid ester acyltransferase (SAET) from is one of the enzymes with the highest catalytic ability for the biosynthesis of l-alanyl-l-glutamine (Ala-Gln) with unprotected l-alanine methylester and l-glutamine. To improve the catalytic performance of SAET, a one-step method was used to rapidly prepare the immobilized cells (SAET@ZIF-8) in the aqueous system. The engineered (. ) expressing SAET was encapsulated into the imidazole framework structure of metal organic zeolite (ZIF-8). Subsequently, the obtained SAET@ZIF-8 was characterized, and the catalytic activity, reusability and storage stability were also investigated. Results showed that the morphology of the prepared SAET@ZIF-8 nanoparticles was basically the same as that of the standard ZIF-8 materials reported in literature, and the introduction of cells did not significantly change the morphology of ZIF-8. After repeated use for 7 times, SAET@ZIF-8 could still retain 67% of the initial catalytic activity. Maintained at room temperature for 4 days, 50% of the original catalytic activity of SAET@ZIF-8 could be retained, indicating that SAET@ZIF-8 has good stability for reuse and storage. When used in the biosynthesis of Ala-Gln, the final concentration of Ala-Gln reached 62.83 mmol/L (13.65 g/L) after 30 min, the yield reached 0.455 g/(L·min), and the conversion rate relative to glutamine was 62.83%. All these results suggested that the preparation of SAET@ZIF-8 is an efficient strategy for the biosynthesis of Ala-Gln.
来自[具体来源未提及]的α-氨基酸酯酰基转移酶（SAET）是利用未保护的L-丙氨酸甲酯和L-谷氨酰胺生物合成L-丙氨酰-L-谷氨酰胺（Ala-Gln）时催化能力最高的酶之一。为了提高SAET的催化性能，采用一步法在水体系中快速制备固定化细胞（SAET@ZIF-8）。将表达SAET的工程化[具体微生物未提及]（[具体菌株名称未提及]）封装到金属有机沸石（ZIF-8）的咪唑框架结构中。随后，对所得的SAET@ZIF-8进行表征，并研究其催化活性、可重复使用性和储存稳定性。结果表明，制备的SAET@ZIF-8纳米颗粒的形态与文献报道的标准ZIF-8材料基本相同，细胞的引入并未显著改变ZIF-8的形态。重复使用7次后，SAET@ZIF-8仍可保留初始催化活性的67%。在室温下保存4天，SAET@ZIF-8可保留其原始催化活性的50%，表明SAET@ZIF-8在重复使用和储存方面具有良好的稳定性。当用于Ala-Gln的生物合成时，30分钟后Ala-Gln的最终浓度达到62.83 mmol/L（13.65 g/L），产量达到0.455 g/(L·min)，相对于谷氨酰胺的转化率为62.83%。所有这些结果表明，制备SAET@ZIF-8是Ala-Gln生物合成的一种有效策略。
