Immobilization–stabilization of an α-galactosidase from Thermus sp. strain T2 by covalent immobilization on highly activated supports: Selection of the optimal immobilization strategy

A very stable α-galactosidase from Thermus sp. T2 has been immobilized on different supports activated with glyoxyl, epoxy or glutaraldehyde groups. Although all preparations retained very high activity (usually over 90%) and all immobilization protocols improved the enzyme stability, the best stability was obtained by immobilization on glutaraldehyde activated supports. Using glutaraldehyde, we compared the immobilization of the enzyme on pre-activated supports or the modification with glutaraldehyde of the enzyme previously adsorbed on amino-supports. The last strategy gave even more stable preparations, retaining over 90% of initial activity. Optimal conditions for the preparation of the immobilized preparations were 1% (v/v) glutaraldehyde and support activated with 40 μmol/mL of support. This preparation retained 90% initial activity after 48 h at pH 7 and 75 °C while the soluble enzyme was fully inactivated after only 8 h. Moreover, this immobilization protocol improved the optimal temperature from 65 °C (soluble enzyme) to 70 °C.