Investigation of benzaldehyde lyase (BAL, EC 4.1.2.38) immobilization and reactions on magnetic nanoparticles

Epoxy-functionalized Fe3O4@SiO2 core?shell magnetic nanoparticles were prepared by modification with glycidyloxypropyl trimethoxysilane (GPTMS) for direct benzaldehyde lyase enzyme (BAL, EC 4.1.2.38) immobilization. First, magnetite nanoparticles were synthesized by co-precipitating Fe2+ and Fe3+ in an ammonia solution. Then silica was coated on the Fe3O4 nanoparticles using a sol?gel method to obtain magnetic silica nanoparticles. The condensation product of 3-Glycidoxypropyltrimethoxysilane (GPTMS) was immobilized on them. The epoxy coated magnetic silica were applied for the covalent immobilization of BAL. X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) methods were used to characterize the epoxy-functionalized Fe3O4@SiO2 core?shell magnetic nanoparticles. XRD (Scherer?s equation) and TEM results indicate that the primary particle size of magnetite was around 11 nm. FTIR results indicate that epoxysilane was attached successfully to the surface of the Fe3O4@SiO2 core?shell magnetic nanoparticles.Histidine-tagged recombinant benzaldehyde lyase (BAL, EC 4.1.2.38) was efficiently immobilized to surface-modified magnetic particles with covalent binding that was used to catalyze the self acyloin condensation reaction of benzaldehyde and cross acyloin condensation reaction of benzaldehyde with acetaldehyde. The same system was used for kinetic resolution of racemic benzoin with acetaldehyde and high yield and selectivity was obtained. In all the reactions, the BALepoxy support system was able to catalyze both C-C bond forming and breaking reactions with high yield and high enantioselectivity (98-?99%ee, 90% yield). The absolute configuration of the products is assigned as (R). The results obtained from the carboligation reactions that were performed with this simple and convenient heterogeneous biocatalyst were comparable to that of free enzyme-catalyzed reactions.Additional advantages are its reusability and it is easy to work with.Keywords: Magnetite; magnetic nanoparticles; surface modification, Benzaldehyde lyase (BAL )enzyme, magnetic purification