Influence of temperature on the activity and enantioselectivity of Burkholderia cepacia lipase in the kinetic resolution of mandelic acid enantiomers

The effect of temperature on Burkholderia cepacia lipase (Amano PS) activity and enantioselectivity in the kinetic resolution of mandelic acid has been investigated. Experiments were carried out at temperatures between 25 and 60 degrees C. The Bi Bi Ping Pong model has been used to calculate kinetic parameters of the transesterification of mandelic acid by vinyl acetate. The rate of transesterification of R enantiomer was found to be substantially lower than that of S enantiomer. A decrease in the reaction rates was observed in temperature above 55 degrees C. The equilibrium model of enzyme deactivation was used to describe the dependence of mandelic acid transesterification rate on temperature. The enthalpy and entropy of the enzyme inactivation have been estimated. The enantioselectivity, expressed as enantiomeric ratio (eta(E)), was very high and decreased a little with the temperature increase. The transition state theory was used to determine the thermodynamic activation parameters. The (S)-mandelic acid transesterification has been found to be enthalpically and entropically favoured. The differentiation of mandelic acid enantiomers in the reaction conditions is driven by the difference in activation enthalpy and entropy as well as by the energy of the substrate binding. (C) 2009 Elsevier B.V. All rights reserved.