Co-immobilization of lipases and β-d-galactosidase onto magnetic nanoparticle supports: Biochemical characterization

Abstract This article describes a model for co-immobilization of multiple enzymes onto a magnetic support. Lipase from Thermomyces lanuginosus (TLL) and β- d -galactosidase from Kluyveromyces lactis (βGal) were selected for this study. TLL was immobilized onto hydrophobic magnetic nanoparticles from magnetite (Fe 3 O 4 ) by a physical adsorption mechanism and was modified by chemical amination of surface carboxylic groups with ethylenediamine using a 1-ethyl-3-(dimethylaminopropyl) carbodiimide coupling method. The enzymatic derivate containing the adsorbed lipase had a 5–fold factor hyperactivation after the immobilization, and the residual activity decreased by 40% after chemical amination. βGal was co-immobilized on the aminated derivate by ion exchange. The post-treatment of the co-immobilized derivate with each of the cross-linking agents (glutaraldehyde and aldehyde-dextran) was studied to improve the stability of the enzymes. The derivates showed a better thermal stability than the enzymes in their free form (50 °C for TLL and 30 °C for βGal), increasing their thermal stabilities, and allowing their use over a wide pH range and up to 50 °C for βGal and up to 70 °C after the cross-linking step.