Preparation and Characterization of Cross-linked Enzyme Aggregates of Saccharomyces Cerevisiae Invertase

Invertase produced by Saccharomyces cerevisiae was immobilized as cross linked enzyme aggregate (CLEA) via precipitation with saturated solution of ammonium sulphate and cross linked with glutaraldehyde. The effect of precipitation and cross linking on CLEA activity were investigated and immobilized invertase was characterized. 40% (v/v) ammonium sulphate saturation, 1.5 %( v/v) glutaraldehyde were used; an 8-h cross linking reaction at room temperature, at pH 7 was performed and 100% activity recovery was achieved in CLEAs with enhanced thermal and acidic condition stabilities. Significant changes in optimum pH and temperature values of the enzyme were recorded after immobilization. From the enzyme kinetic study, decrease in substrate affinity and velocity of enzyme reaction were observed. Highly stable CLEAs can be prepared from crude Saccharomyces cerevisiae invertase