The Stability of β-galactosidase (Aspergillus oryzae) Immobilized on Eupergit C

D. Huzjak*, Jasna Huzjak** and J. Križanić*

*Belupo d.o.o., Sektor razvoja proizvoda, Koprivnica, Croatia
**Podravka d.d., FC-istraživanja i razvoj, Koprivnica, Croatia

Article history:
Received September 9, 1994
Accepted December 22, 1994

Summary:
The stability of β-galactosidase (A. oryzae) covalently immobilized on epoxy-activated acrylic beads (Eupergit C) was examined and compared with the stability of the native enzyme. Immoblization of β-galactosidase to Eupergit C was carried out in 1 M potassium phosphate buffer, pH = 7.5 at room temperature for 24 h. Comparative investigations have shown that immobilization had no significant effect on the pH stability of β-galactosidase from A. oryzae. Also, immobilization had no effect on the stability of enzyme preparations toward ionic strength of storage buffer, or to proteolytic activity of proteinases from Streptomyces griseus ("pronase P"). On the other hand, it was found that the immobilization on Eupergit C results in an increased thermal stability of β-galactosidase. Immobilized β-galactosidase from A. oryzae was also much more resistant to denaturation at high urea concentration than a native enzyme.