Gen-Hai Zhao, Hui Li, Wei Liu, Wei-Guo Zhang, Fei Zhang, Qian Liu, Qing-Cai Jiao
State Key Laboratory of Pharmaceutical Biotechnology, School of Life Science, Nanjing University, Nanjing 210093, People's Republic of China.
Amino acids 2011 JanIn this research, an improved method for preparation of optically pure β-hydroxy-α-amino acids, catalyzed by serine hydroxymethyl transferase with threonine aldolase activity, is reported. Using recombinant serine hydroxymethyl transferase (SHMT), an enzymatic resolution process was established. A series of new substrates, β-phenylserine, β-(nitrophenyl) serine and β-(methylsulfonylphenyl) serine were used in the resolution process catalyzed by immobilized Escherichia coli cells with SHMT activity. It was observed that the K (m) for L: -threonine was 28-fold higher than that for L: -allo-threonine, suggesting that this enzyme can be classified as a low-specificity L: -allo-threonine aldolase. The results also shows that SHMT activity with β-phenylserine as substrate was about 1.48-fold and 1.25-fold higher than that with β-(methylsulfonylphenyl) serine and β-(nitrophenyl) serine as substrate, respectively. Reaction conditions were optimized by using 200 mmol/l β-hydroxy-α-amino acid, and 0.1 g/ml of immobilized SHMT cells at pH 7.5 and 45°C. Under these conditions, the immobilized cells were continuously used 10 times, yielding an average conversion rate of 60.4%. Bead activity did not change significantly the first five times they were used, and the average conversion rate during the first five instances was 84.1%. The immobilized cells exhibited favourable operational stability.
Gen-Hai Zhao, Hui Li, Wei Liu, Wei-Guo Zhang, Fei Zhang, Qian Liu, Qing-Cai Jiao. Preparation of optically active β-hydroxy-α-amino acid by immobilized Escherichia coli cells with serine hydroxymethyl transferase activity. Amino acids. 2011 Jan;40(1):215-20
PMID: 20514546
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