Immobilization of feruloyl esterases in mesoporous silica

Conference poster, 2011

Mesoporous silica materials have become popular as immobilization support for enzymes due to advantages such as high protein loading capacity and enhanced enzyme activity because of confinement into pores. Immobilization of enzymes is often required for sufficient enzyme stability and to enable recovery in industrially feasible and efficient processes. Feruloyl esterases is a class of enzymes used in biocatalysis for refinement of hydroxycinnamic acids. These compounds have shown to have antioxidant and antibacterial properties, though modification of solubility is necessary for the compounds to be of interest in different commercial products. Previous work has showed that mesoporous silica is a robust immobilization support for feruloyl esterases and that transesterification activity was favored over hydrolysis. Immobilization of feruloyl esterases (FoFAEC) in SBA-15 mesoporous silica showed to be highly affected by pH. Testing the immobilized enzymes for transesterification of methyl ferulate to butyl ferulate showed that the specific activity was affected by the pH at which the enzymes had been immobilized. Consequently there is a pH memory effect, which could be reverted by subsequent washing with a buffer of different pH. The current work involves testing a pH probe bound to the enzyme which will give information of the microenvironment pH close to the enzyme. Additionally, an in silico model of FoFAEC has been developed so that the dimensions of the enzyme can be related to the pore size. The model will also be used to simulate the enzyme structure at different pH, predict orientation and adsorption behavior. The aim is to understand how mesoporous materials can be used to alter the enzymatic activity upon immobilization and in the end develop improved feruloyl esterase biocatalysts that allow customization of the antioxidant properties of hydroxycinnamic acids.