Influence of aldehyde groups on the thermostability of an immobilized enzyme on an inorganic support

The influence of glutaraldehyde cross-linking on the thermostability of an immobilized enzyme on an inorganic support is described. A thermostable β-galactosidase derived from a thermophile was covalently linked to a silanized porous inorganic support with glutaraldehyde. The effect of the amount of the immobilized enzyme on its thermostability was investigated at different temperatures and it was found that a combination of a low enzyme/support (g enzyme/g support) and high incubation temperature resulted in a considerable decrease in the residual activity. The thermostability of the immobilized enzyme under these conditions was improved by additional treatment with a solution of basic amino acids after immobilization procedure. These results suggest that the stability at high temperature of an immobilized enzyme by glutaraldehyde cross-linking is remarkably affected by free aldehyde groups remaining on the surface of an inorganic support. Therefore, it is important to eliminate free aldehyde groups for preventing the surface from influencing the enzymes at high incubation temperature.