Feruloyl esterases for biosynthesis in mesoporous silica
Conference poster, 2011
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. Immobilization of enzymes is often required for sufficient enzyme stability and to enable recovery in industrially feasible and efficient processes. Mesoporous silica 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. Upon immobilization of feruloyl esterases (FoFAEC) into mesoporous silica (SBA-15), the selectivity was altered towards transesterification while the hydrolytic activity was decreased compared to free enzyme. It is remarkable how adsorption of the enzyme so drastically can change its catalytic properties.
We have demonstrated that the immobilization efficiency is highly affected by the pH during the immobilization, which also had an effect on the specific activity when testing the immobilized enzymes for transesterification of methyl ferulate to butyl ferulate. Consequently there is a pH memory effect from the immobilization, which could be reverted by subsequent washing with a buffer of different pH. The aim of our research 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. We will approach this by 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 to simulate the enzyme structure at different pH and to predict orientation and adsorption behavior.