A novel control of enzymatic enantioselectivity through the racemic temperature influenced by reaction media

The influence of reaction media on the racemic temperature (Tr) in the lipase-catalyzed resolution of ketoprofen vinyl ester was investigated. An effective approach to the control of the enzymatic enantioselectivity and the prediction of the increasing tendency was developed based on the Tr influenced by reaction media. The Tr for the resolution catalyzed by Candida rugosa lipase (CRL) was found at 29 °C in aqueous and S-ketoprofen was obtained predominantly at 40 °C. However, CRL showed R-selectivity at 40 °C in diisopropyl ether because the Tr was changed to 56 °C. CRL, lipase from AYS Amano® and Mucor javanicus lipase were further applied for the investigation of the enzymatic enantioselectivity in dioxane, DIPE, isooctane and their mixed media with water. The effects of the reaction medium on Tr could be related to the solvent hydrophobicity, the lipase conformational flexibility and the interaction between the enantiomers and the lipase.