α-Glucosidase immobilization on chitosan-enriched magnetic composites for enzyme inhibitors screening.

In the present study, the chitosan-enriched magnetic composites (MCCs) were prepared by a novel and simple embedding method for the immobilization of α-glucosidase (α-Glu). The immobilized α-Glu could be easily separated from the reaction mixture under an external magnetic field owing to the magnetic support. With the MCCs-immobilized α-Glu, enzyme activity and stability were studied, and enzyme inhibitors were screened from traditional Chinese medicines (TCMs) and vegetables combined with capillary electrophoresis (CE). The MCCs-immobilized α-Glu exhibited enhanced pH and temperature tolerance with unchanged optimum pH and temperature of 4.0 and 60°C comparing with free α-Glu. Reusability of the immobilized α-Glu was significantly improved after immobilization, and it retained 62.2% of its initial activity after 10 repeated cycles. Immobilized α-Glu also showed improved storage stability (84.3±1.2% after 35days of storage at 4°C). The kinetic parameter K for immobilized α-Glu was calculated to be 0.81mM and the affinity of enzyme towards its substrate was reduced after immobilization. Finally, immobilized α-Glu was used to screen enzyme inhibitors from the extracts of TCMs and vegetables. The enhanced pH and temperature tolerance, improved reusability and storage stability of MCCs-immobilized α-Glu make it a promising candidate for biotechnological applications.