Kinetics Based on the Rapid‑Equilibrium Approach for the Reduction of an Achiral Ketone to a Chiral Alcohol by a Single Carbonyl Reductase With NAD(P)H Regeneration Using Isopropyl Alcohol as the Hydrogen Donor

The kinetics of a single-enzyme, substrate-coupled system in batch operation for the asymmetric production of chiral alcohols from achiral ketones through NAD(P)H regeneration-using isopropyl alcohol (IPA) as a hydrogen donor-were investigated. Assuming the effective removal of acetone, two novel mathematical equations were derived by applying the rapid equilibrium approach to four enzyme-substrate complexes: one for the chiral alcohol formation rate, and another modeling its concentration over time under the assumption of a constant IPA concentration. The formation rate equation for batch operation was transformed into a dimensionless form to elucidate how constituent variables and parameters affect the reaction rate. The derived rate equations, which are two-parameter mathematical models, are substantially simpler than those in previously reported studies. The derived product formation rate decreases monotonically and remarkably with reaction time, agreeing with experimental results reported across the literature. The proposed time-course equation was validated against experimental data from two published studies. The fit of the derived equations to the experimental data was satisfactory within acceptable deviations, provided the core assumptions were satisfied.