Storey, K.B., Duncan, J.A. and Chakrabarti, A.C. 1990. Immobilization of amyloglucosidase using two forms of polyurethane polymer. Appl. Biochem. Biotech. 23. 221- 236.

Immobilization of Amyloglucosidase Using Two Forms of Polyurethane Polymer

KENNETH B. STOREY, JOHN A. DUNCAN, AND AJOY C. CHAKRABARTI

ABSTRACT
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 (greater than 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.