Improved activity and stability of lipase immobilized in cage-like large pore mesoporous organosilicas

Abstract

Lipase from Thermomyces lanuginosus has been immobilized in different mesoporous organosilicas (PMOs) containing ethane and benzene groups with large cage-like pores. The immobilization of lipase as well as the application of these catalysts in hydrolysis and transesterification reactions is studied in detail. The results show that the structural properties of the support employed have a significant influence on the adsorption capacity. In general, materials with high specific surface areas and pore volumes show high adsorption capacity. However, in the case of monolayer adsorption, the hydrophobicity of the surface has a significant impact on the adsorption efficiency due to strong hydrophobic interactions. Furthermore, the transesterification of vinyl propionate with 1-butanol catalyzed by immobilized lipase was studied. The influence of lipase loading, the effect of water content in the reaction mixture and the influence of different solvents were investigated. The results show that lipase immobilized in the most hydrophobic material (LPbenzene) exhibits excellent catalytic performance, which is attributed to the enhanced interfacial activity of lipase due to the interaction between lipase and the hydrophobic surface of the material. In order to further disclose the influence of the hydrophobic surface on the lipase activity, ATR-FTIR spectroscopy was used to study the secondary structure of lipase immobilized on different supports. The results confirm that a structural transition of entrapped lipase to the open-lid conformation takes place on LPbenzene, which shows that the observed increase in enzymatic activity is triggered by interfacial activation of lipase.