Enzymatic kinetic resolution in flow for chiral mandelic acids

During the kinetic resolution process, increased substrate conversion often compromised the optical purity of products. A strategy integrated biotechnology and microtechnology was developed to kinetic resolution of mandelic acids. The effects of temperature, pH, solvent, reaction time, flow rate on the hydrolysis were conducted. Under optimal conditions, the MCR reaction afforded 95% ee_p, whereas the batch reaction yielded 65% ee_p. The kinetics of hydrolysis was also investigated. The value for K_m and V_max in batch was 12 mM and 11 mM s⁻¹, while that in MCR was 8 mM, 45 mM s⁻¹. This means more substrates can be transferred to the active site on the enzyme in MCR at the same concentration. This is a benefit from the excellent mass transfer limitations in MCR. Furthermore, the apparent V_max was significantly increased, closer to the intrinsic rate of reaction. Finally, the strong mass transfer in MCR leads to an expanded rate difference between (R) enantiomers and (S) enantiomers, improving the ee_p and E-values.