A novel strategy for efficient chemoenzymatic synthesis of D-glutamine using recombinant Escherichia coli cells

D-glutamine is a D type stereoisomer of glutamine which is involved in many metabolic processes. Seeking lower-cost and industrially scalable approaches for the synthesis of D-glutamine is very valuable both in academic career and potential applications. Herein, we developed a novel efficient chemoenzymatic strategy for producing D-glutamine. Initially, DL-glutamine was chemically prepared with cheap and accessible DL-glutamic acid as raw material. Subsequently, the L-glutamine among the racemic mixture was selectively hydrolyzed to L-glutamic acid by Escherichia coli whole-cell system which expressed L-aminopeptidase D-Ala-esterase/amidase (DmpA) from Ochrobactrum anthropi. The left D-glutamine was obtained by isoelectric point precipitation with 70% of the theoretical yield. Furthermore, we optimized enzymatic resolution conditions to determine the optimum parameters as pH 8, 30 degrees C, 0.1% (v/v) Triton X-10 0, and 1 mM Mn-2 thorn . These results suggested that our strategy might be potentially usable for the synthesis of D-glutamine in industrial productions. (C) 2020 Elsevier B.V. All rights reserved.