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

Abstract

α-Glucosidase from S. cerevisiae was covalently immobilized onto Sepabeads EC–EA by the glutaraldehyde method. An analysis of the variables controlling 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 optimum pH, but a higher optimum temperature compared with the soluble one. In addition, 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 simple, easily reproducible and provides a promising solution for the application of immobilized α-glucosidase