Bilayer glucose isomerase was immobilized in porous p-trimethylamine-polystyrene (TMPS) beads through a molecular deposition technique. Some of the factors that influence the activity of immobilized glucose isomerase were optimized, with the enzyme concentration of 308 IU/mL, enzyme-to-matrix ratio of 924 IU/g wet carrier, and hexamethylene bis(trimethylammonium iodine) concentration of 15 mg/mL giving the maximum catalytic activity (2238 IU/g dry gel) of the immobilized bilayer glucose isomerase, retaining 68.5% of the initially added activity. The half-life of the immobilized bilayer glucose isomerase was approx 45 d at pH 8.5, 60 degrees C, with 50% (w/v) glucose as substrate. The specific productivity of the immobilized bilayer glucose isomerase was 223 g dry D-glucose/g dry immobilized enzyme per d.