Rational identification of a high catalytic efficiency leucine dehydrogenase and process development for efficient synthesis ofl‐phenylglycine

Abstract

AbstractEnzymatic asymmetric synthesis of chiral amino acids has great industrial potential. However, the low catalytic efficiency of high‐concentration substrates limits their industrial application. Herein, using a combination of substrate catalytic efficiency prediction based on “open to closed” conformational change and substrate specificity prediction, a novel leucine dehydrogenase (TsLeuDH), with high substrate catalytic efficiency toward benzoylformic acid (BFA) for producingl‐phenylglycine (l‐Phg), was directly identified from 4695 putative leucine dehydrogenases in a public database. The specific activity ofTsLeuDH was determined to be as high as 4253.8 U mg−1. Through reaction process optimization, a high‐concentration substrate (0.7 m) was efficiently and completely converted within 90 min in a single batch, without any external coenzyme addition. Moreover, a continuous flow‐feeding approach was designed using gradient control of the feed rate to reduce substrate accumulation. Finally, the highest overall substrate concentration of up to 1.2 mBFA could be aminated tol‐Phg with conversion of >99% in 3 h, demonstrating that this new combination of enzyme process development is promising for large‐scale application ofl‐Phg.