Henriques_2018_Mol.Catal_453_12

This article describes a model for co-immobilization of multiple enzymes onto a magnetic support. Lipase from Thermomyces lanuginosus (TLL) and beta-d-galactosidase from Kluyveromyces lactis (betaGal) were selected for this study. TLL was immobilized onto hydrophobic magnetic nanoparticles from magnetite (Fe3O4) 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. betaGal 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 degreesC for TLL and 30 degreesC for betaGal), increasing their thermal stabilities, and allowing their use over a wide pH range and up to 50 degreesC for betaGal and up to 70 degreesC after the cross-linking step.