IMMOBILIZATION IN ALGINATE-SILICATE SOL-GEL MATRIX PROTECTS BETA-GLUCOSIDASE AGAINST THERMAL AND CHEMICAL DENATURATION

We have developed a novel immobilization medium by soaking enzyme-cont aining calcium alginate beads in a solution of tetramethoxy-ortho-sili cate (TMOS) in hexane. Water-soluble alkyl siloxanes, resulting from t he partial hydrolysis of TMOS at the hexane-water interface permeated the alginate gel, polymerized and formed a colloid within the beads. S ilicate-alginate beads were robust, and did not deform under pressure. The composite gel demonstrated the excellent protein retention and th ermal stabilization properties typical of silicate sol-gel-immobilizat ion, as well as protection against inactivation by concentrated urea s olutions. Immobilized beta-glucosidase had complete operational stabil ity at ambient temperature for at least several months.