Effect of solvents on structural stability and catalytic activity of Lipase Amano 30SD in EGCG esterification reaction estimated by FTIR and MD simulations

Abstract

The structure of lipase is easily influenced by the type of solvent, which will impact its catalytic efficiency and selectivity in (−)-epigallocatechin gallate (EGCG) esterification reaction. Therefore, in this study, Lipase Amano 30SD was used to catalyze EGCG esterification reaction in different solvents. The structural changes of Lipase Amano 30SD in different solvents were analyzed using fourier transform infrared spectroscopy and molecular dynamics simulations to explain the impact of solvents on EGCG esterification reaction. The results indicated that Lipase Amano 30SD has higher conversion rate of EGCG in acetonitrile and monoacetylated, diacetylated, and triacetylated EGCG were generated, which is associated with the good flexibility of its active site in acetonitrile system. Only monoacetylated EGCG was generated in isopropanol owing to its more rigid active site than that in acetonitrile. The low conversion rate of EGCG in methanol may be due to the hydrogen bonds formed by methanol with Ser209 and His449, which hinders the contact between lipase and substrates. This study suggested that flexible active site was conducive to EGCG esterification reaction, but not conducive to the regioselectivity of lipase.