In recent years, there has been increasing interest in the use of regenerated silk fibroin for applications, such as medical scaffolds, carriers for drug delivery and enzyme immobilization. In the present work, enzymatic oxidization of silk fibroins with tyrosinase was carried out. An amount of catalase was subsequently added into the bath to initiate the coupling of catalase to silk fibroins. The porous fibroin membrane containing immobilized catalase was eventually obtained after freeze-drying. The result indicated that tyrosine residues in silk fibroins could be oxidized and converted to active quinones, which led to an increase in the absorbance at 350nm. Individual tyrosianse treatment incurred self-crosslinking of fibroin proteins, which could be verified by the result from gel filtration chromatography. When incubating silk fibroins with catalase and tyrosinase, the newly-formed proteins were detected according to the SDS-PAGEs, indicating that the catalase was covalently coupled onto the surface of silk fibroins. The enzyme activity for the immobilized catalase was higher than that of the control. The alkali resistance and thermal stability for the immobilized catalase were slightly increased, while the optimal pH and temperature were not remarkably affected. The durability of immobilized catalase was needed to be further improved owing to the partial adsorption of enzyme onto silk fibroins. The results from the DSC and ATR-FTIR suggested that the thermodynamic property and secondary structure of silk fibroin carriers were not affected by the enzymatic immobilization.

Tyrosinase-catalyzed immobilization of catalase onto regenerated silk fibroins

249th National Meeting (2015)

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