Teaching reform and practice of "food enzymology and enzyme engineering" based on cutting-edge researches / 生物工程学报

Food enzymology and enzyme engineering is an important professional course of food science. The course includes the basic theory of enzymology, enzyme engineering technology and the application of enzymes in food industry. Considering the knowledge gap between the teaching contents and the cutting-edge researches, the team constantly adjusted and optimized the course contents to enable students to keep up with state-of-the-art progress by carefully mining the cutting-edge researches. Taking cutting-edge researches as the breakthrough point, we explored the problem-based learning (PBL) teaching model under the guidance of outcome-based education (OBE) concept, and highlighted the importance of the teacher-student and student-student interactions to improve students' enthusiasm and participation. A diversified assessment system was established to evaluate the performance of students in the learning process. The teaching reform consolidated the basic knowledge and expanded the academic frontiers, and fostered students' ability in analyzing problems, designing solutions and achieving team communication. The course may give new insights into the teaching reform of food enzymology and enzyme engineering and other related courses.

Catalytic mechanism, molecular engineering and applications of threonine aldolases / 生物工程学报

Threonine aldolases catalyze the aldol condensation of aldehydes with glycine to furnish β-hydroxy-α-amino acid with two stereogenic centers in a single reaction. This is one of the most promising green methods for the synthesis of optically pure β-hydroxy-α-amino acid with high atomic economy and less negative environmental impact. Several threonine aldolases from different origins have been identified and characterized. The insufficient -carbon stereoselectivity and the challenges of balancing kinetic versus thermodynamic control to achieve the optimal optical purity and yield hampered the application of threonine aldolases. This review summarizes the recent advances in discovery, catalytic mechanism, high-throughput screening, molecular engineering and applications of threonine aldolases, with the aim to provide some insights for further research in this field.

Expression and characterization of a novel ω-transaminase from Burkholderia phytofirmans PsJN / 生物工程学报

Production of chiral amines and unnatural amino-acid using ω-transaminase can be achieved by kinetic resolution and asymmetric synthesis, thus ω-transaminase is of great importance in the synthesis of pharmaceutical intermediates. By genomic data mining, a putative ω-transaminase gene hbp was found in Burkholderia phytofirmans PsJN. The gene was cloned and over-expressed in Escherichia coli BL21 (DE3). The recombinant enzyme (HBP) was purified by Ni-NTA column and its catalytic properties and substrate profile were studied. HBP showed high relative activity (33.80 U/mg) and enantioselectivity toward β-phenylalanine (β-Phe). The optimal reaction temperature and pH were 40 ℃ and 8.0-8.5, respectively. We also established a simpler and more effective method to detect the deamination reaction of β-Phe by UV absorption method using microplate reader, and demonstrated the thermodynamic property of this reaction. The substrate profiling showed that HBP was specific to β-Phe and its derivatives as the amino donor. HBP catalyzed the resolution of rac-β-Phe and its derivatives, the products (R)-amino acids were obtained with about 50% conversions and 99% ee.