Immobilization and characterization of feruloyl esterase enzyme to different supports and obtaining ferulic acid from wheat bran

In this study, the recombinant feruloyl esterase (FAE) enzyme was covalently immobilized on 3-aminopropyl silica gel support (FAE-3Ap-Glu) via glutaraldehyde spacer arm, entapped in PVA (FAE-PVA), sol gel (FAE-sol gel), and iron nanoparticle silica composites (FAE-nano). The optimum pH and temperature, thermal and storage stability and kinetic parameters were determined for the free and immobilized FAEs. For immobilized FAEs, the reuse stability was determined in a batch reactor. The optimum pH for free FAE, FAE-3Ap-Glu, FAE-PVA, FAE-sol gel and FAE-nano was 6.5, 6.5, 7.0, 7.0, and 7.5, respectively. The optimum temperature for free FAE, FAE-3Ap-Glu, FAE-PVA was found to be 40°C, and 60°C and 70°C for FAE-sol gel and FAE-nano, respectively. It was determined that the thermal and storage stability of all immobilized enzyme samples were considerably higher than the free enzymes. FAE-nano, which retained approximately 63% of its initial activity after 10 reuses in a batch reactor, was identified as the immobilized FAE with the highest reuse stability. The Km values of free FAE, FAE-3Ap-Glu, FAE-PVA, FAE-sol gel and FAE-nano were 2.94, 2.26, 2.69, 1.09, and 6.91 mM, respectively. The corresponding Vmax values were 0.23, 0.40, 0.16, 0.12, and 0.50 U/mg protein.