Abstract Ethyl (R)-2-hydroxy-4-phenylbutyrate ((R)-HPBE) is used as an intermediate in the production of angiotensin converting enzyme (ACE) inhibitors for treating various medical conditions. The study used Stereospecific carbonyl reductase (KmCR) enzyme for the asymmetric synthesis of (R)-HPBE. The optimization process involved varying IPTG concentration, induction temperatures, and induction times to determine the optimal culture conditions for producing (R)-HPBE with increased yields. The most efficient culture conditions were determined as 0.2 mM IPTG concentration, 17 °C temperature, and 10 hours of induction. Additionally, the study explored various reaction parameters, including temperature, substrate concentration, enzyme concentration, co-solvents, and their ratios, to optimize the reaction conditions for synthesizing (R)-HPBE with higher productivity. The optimal reaction conditions were found at 25 °C, substrate concentration of 10.3 g·L-1, enzyme concentration of 50 g·L-1, and isopropanol co-solvent with a ratio of 10%. The optimized conditions produced 62% yield of (R)-HPBE with an optical purity of ≥99.9% and a reaction time of 20 minutes. These findings provide valuable insights for potential large-scale production using the identified optimal parameter concentrations.
Keywords Kluyveromyces marxianus carbonyl reductase (KmCR),(R)-2-hydroxy-4-phenylbutyrate, ethyl-2-oxo-4-phenylbutyrate, asymmetric transformation, stereospecificity.