Preparation and studies on immobilized α-glucosidase from baker’s yeast Saccharomyces cerevisiae

α-Glucosidase from S. cerevisiae was covalently immobilized onto Sepa- beads EC-EA by the glutaraldehyde method. An analysis of the variables control- ling the immobilization process is first presented and it is shown that the highest coupling of α-glucosidase occurred within 24 h. Also, a loading of 30 mg/g support proved to be effective, resulting in a rather high activity of around 45 U g -1 with a satisfactory degree of enzyme fixed. Both free and immobilized enzymes were then characterized by determining the activity profile as a function of pH, temperature and thermal stability. The obtained immobilized preparation showed the same opti- mum pH, but a higher optimum temperature compared with the soluble one. In ad- dition, the immobilized enzyme treated at 45 oC for 1 h still retained an activity of around 20 %, whereas the free enzyme completely lost its original activity under this condition. In conclusion, the developed immobilization procedure is quite sim- ple, easily reproducible and provides a promising solution for the application of immobilized α-glucosidase.