Influence of acyl chain length on the enantioselectivity of Candida antarctica lipase B and its thermodynamic components in kinetic resolution of sec-alcohols

The enantioselectivity, E, of Candida antarctica lipase B (CALB) was found to be strongly influenced by the chain length of the achiral acyl donor employed in the transesterification of 3-methyl-2-butanol. Of the four studied acyl donors, the longest, vinyl octanoate, afforded the highest enantioselectivity. This was true over the temperature range studied, 6-70 degreesC. Measurements of the temperature dependence of E allows for separation of the enthalpic and entropic components of enantioselectivity. Changes in E with chain length were mainly caused by changes in the entropic component except for the reaction with vinyl propionate, which differed from the others also in the enthalpic component. Optimisation of acyl donor adds one more possibility to improve the yield of enantiopurity in the production of optically active compounds apart from optimisation of solvent, temperature, water activity, and choice of enzyme. (C) 2001 Elsevier Science B.V. All rights reserved.