Abstract
The immobilization of glucose isomerase (Dβxylose ketol isomerase, EC 5.3.1.5) by covalently bonding to various carriers and by adsorption to ion exchange resins was attempted in order to obtain a stable immobilized enzyme which can be used for continuous isomerization of glucose in a column.
Of the covalent bonding methods, the colloidal silicaβglutaraldehyde method showed the highest binding capacity and gave the stablest immobilized glucose isomerase. The LUDOX HSβ30 bound glucose isomerase column showed a halfβlife of 24 days and an enzyme usage of 0.07 units per gram of isomerized sugar (d.s., fructose 45%).
Of the resins used, the macromolecular type or porous type strongly basic anion exchange resins showed the highest binding capacity and gave the stablest immobilized glucose isomerase. The Amberlite IRAβ904 resineβbound glucose isomerase showed a halfβlife of 23 days and an enzyme usage of 0.06 units per gram of isomerized sugar (d. s., fructose 45%).
Based on the ease of the immobilization process, the possibility of carrier ruse the extensive use already achieve by ion exchange resins in the sugar industry, IRAβ904 resin was selected as the candidate for commercialization.