Molecular dynamics simulation study of lipase-catalyzed esterification of structural butanol isomers in supercritical carbon dioxide

Lipase-catalyzed esterification of structural butanol isomers and n-butyric acid was investigated in supercritical, carbon dioxide, The experiments were performed in a high pressure cell for 5 hrs with a stirring rate of 150 rpm at 323.1.5 K and 1.30 bar. The Candida Antarctica lipase B (CALB) was used in whole system as a catalyst. The experimental results were analyzed by GC-FID using a INNOWax capillary column. The conversion yield and the tendency of the esterification in supercritical carbon dioxide were compared with estimated results by molecular dynamics simulation. Based on the Ping-Pong Bi-Bi mechanism with competitive inhibition, each step of the reaction was optimized; using this result the transition state was predicted. Conformational preference of isomers was also analyzed using molecular dynamics simulations. This kind of approach, will be further extended to the prediction of enzyme-catalyzed reactions using computers.