Cellulose filter paper immobilized -glucosidase and its application to screening inhibitors from traditional Chinese medicine

In this study, alpha-glucosidase was successfully immobilized on cellulose filter paper and further applied to screening inhibitors from traditional Chinese medicines combined with capillary electrophoresis analysis. For alpha-glucosidase immobilization, a cellulose filter paper was used as the carrier and grafted with amino groups by coating chitosan, then alpha-glucosidase was covalently bonded on the amino-modified carrier via epoxy ring-opening reaction using polyethylene glycol diglycidyl ether as the crosslinker. Several parameters influencing the enzyme immobilization were optimized and the optimal values were enzyme concentration of 4 U/ml, polyethylene glycol diglycidyl ether concentration of 1.25%, chitosan concentration of 7.5 mg/ml, immobilization pH 7.0, crosslinking time of 4 h and immobilization time of 2 h. The immobilized alpha-glucosidase exhibited good hatch-to-batch reproducibility (RSD = 2.1%, n = 5), excellent storage stability (73.5% of its initial activity after being stored at 4 degrees C for 15 days), and reusability (75% of its initial activity after 10 repeated cycles). The Michaelis constant of immobilized alpha-glucosidase and half-maximal inhibitory concentration of acarbose were calculated to be 1.12 mM and 0.38 mu M, respectively. Finally, the immobilized alpha-glucosidase was used for screening inhibitors from 14 kinds of Traditional Chinese Medicine extracts, and Sanguisorbae Radix showed the strongest inhibitory effect on alpha-glucosidase.