Amyloglucosidase was covalently immobilized using two hydrophilic prepolymers: Hypol® FHP 2002 (creates foams) and Hypol® FHP 8190H (creates gels). The foamable prepolymer was superior as a support for enzyme immobilization. The percent activity immobilized in the polyurethane foams was 25 ± 1.5%. Large substrates (> 200,000 daltons in mol wt) were hydrolyzed as effectively as smaller ones by the immobilized enzyme. The Km value of the foam-immobilized enzyme increased from 0.76 mg/mL (free) to 0.86 mg/mL (immobilized), whereas the Vmax dropped from 90.9 (free) to 12.4 nmol glucose/min/ mL (immobilized). The long-term (2 mo) storage stability of amyloglucosidase was enhanced by immobilization in foams (70% activity retained; free enzyme only retained 50%). Immobilization also improved the enzyme stability to various denaturing agents (sodium chloride, urea, and ethanol). The immobilized enzyme exhibited increased stability compared to the free enzyme at high temperatures (95°C). Both glycogen and starch could be utilized by the immobilized enzyme, indicating that this technique could prove useful for starch hydrolysis.

Amyloglucosidase, enzyme immobilization, polyurethane polymers, starch degradation
Applied Biochemistry and Biotechnology
Department of Biology

Storey, K, Duncan, J.A. (John A.), & Chakrabarti, A.C. (Ajoy C.). (1990). Immobilization of amyloglucosidase using two forms of polyurethane polymer. Applied Biochemistry and Biotechnology, 23(3), 221–236. doi:10.1007/BF02942056