| Summary: | Procedures of immobilization invertase have been developed using different supports. However, disadvantages such as use of small particles for invertase immobilizations in packed-bed reactors are being solved using magnetic particles. In this study, composites containing Fe3O4 were prepared by incorporation of a polysiloxane layer required for the physical adsorption of the invertase. Besides, the functionalized magnetite was activated with glutaraldehyde and polyethylenimine (PEI) with the aim of performing a covalent immobilization. The effect of different conditions such as enzyme:support ratio, pH, and temperature were analyzed in the preservation of invertase. The results demonstrated that the optimum enzyme:support ratio is higher for covalent bonding than for physical adsorption. The ideal pH for the immobilized enzyme is 5.0, and the enzymatic activity is retained until 70°C. The values of km are similar in both immobilization methods. The analysis of the effect of pH and thermostability showed that the catalytic activity of invertase is not affected in comparison with the free enzyme. The covalent immobilization displays higher efficiency in the immobilization process (Fε), less inhibition and twice as much stability. The enzymes immobilized by physical and covalent methods can be reused for up to four cycles and can be removed from the reaction medium by applying an external magnetic field.
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