Use of chemically modified poly(ethylene terephthalate)-g- (acryl amide) fibers for α-amylase immobilization

Acryl amide grafted Poly(ethylene terephthalate) (AAm-g-PET) fiber was used for covalent coupling of α-amylase. The amide groups of Poly(acryl amide) were converted to the amine groups by Hofmann degradation reaction. The amine groups were activated by glutaraldehyde, before coupling of the enzyme. The free α-amylase and immobilized α-amylase were characterized by determining the activity profile as function of pH, temperature, thermal stability and storage stability. For the immobilized α-amylase, operational stability was also determined. The immobilization of α-amylase on support caused the optimal reaction pH to shift from 5 to 6. The maximum activity of the free and immobilized enzymes occurred at 50 0C. Km for the immobilized system was higher than that for the free enzyme. The activity of the free enzyme ended in 30 days, whereas the activity of the immobilized enzyme lasted for 60 days at storage conditions. α-Amylase immobilized on matrix maintained 40% of its original activity after 30 times of repeated use.