Stereoselective synthesis of (1R, 2S)-norephedrine by recombinant whole-cell biocatalysts coupling acetohydroxyacid synthase I and ω-transaminase

Autor: Kun-Xin Liang, Jian-Sin Lin, Chao-Hung Kao, Hsin-Hua Chan, Wei-De Lin, Yih-Yuan Chen, Chia-Chen Li, Yen-Chung Lee, Yi-Wun Chen
Rok vydání: 2018
Předmět:
Zdroj: Process Biochemistry. 73:74-81
ISSN: 1359-5113
DOI: 10.1016/j.procbio.2018.08.009
Popis: In this study, a combined whole-cell biotransformation process was used for efficient synthesis of optically pure (1 R, 2 S )-norephedrine [(1 R, 2 S )-NE]. The genes encoding R -selective acetohydroxyacid synthase I (AHAS I) from Escherichia coli and S -selective ω-transaminase (ω-TA) from Chromobacterium violaceum BCRC10636 were cloned and over-expressed in E. coli NovaBlue cells. In the first biosynthetic step, l -phenylacetylcarbinol ( l -PAC) was produced from benzaldehyde and pyruvate by using recombinant E. coli (pQE- AHAS I) cells, with almost 100% conversion yield and 71.8% purification yield. The purified l -PAC was coupled to l -alanine by using recombinant E. coli (pQE- CvTA ) cells to produce (1 R, 2 S )-NE. This biocatalytic process was optimal at pH 6.5 to 8.0 and 37 °C, with a 1:10 ratio of l -PAC to l -alanine. Under the optimal conditions, the highest conversion yield of (1 R, 2 S )-NE was 62.2% and the enantiomeric excess value of (1 R, 2 S )-NE was more than 99%. The recombinant E. coli (pQE- CvTA ) cells could be reused for at least 20 cycles, with only a modest reduction in the conversion yield to 76.3% relative to the first cycle. Our results indicate that the combination of AHAS I- and ω-TA-expressing E. coli cells might be a potential biocatalyst for (1 R, 2 S )-NE production.
Databáze: OpenAIRE
Externí odkaz: