Immobilization and enzymatic activity of β-glucosidase on mesoporous SBA-15 silica

The mesoporous silicate SBA-15 has shown to be a good support for the immobilization of beta-glucosidase from almonds, an enzyme with high molecular weight (ca. 130 kDa for the dimer). An enzyme loading of 430 mg per gram of support (3.2 +/- A 0.2 mu mol g(-1) of SBA-15) was achieved at 7 h. The optimum pH for the immobilization was 3.5. The electrostatic interactions between the surface of SBA-15 and the enzyme molecules were the driving force of the adsorption process. The immobilized beta-glucosidase presented enzymatic activity on the hydrolysis of the 4-nitrophenyl-beta-d-glucopyranoside at 3.5 pH. The catalytic activity was similar to the free enzyme for reaction time of 30 min. When the reaction pH was higher (5.5 pH) the enzyme was desorbed.