Mesocellular siliceous foams (MCFs) functionalized with different groups were used in the trypsin immobilization process. Macromolecular reagents were co-assembled with trypsin in the MCFs to create a microenvironment resembling that in living cells. The catalytic characteristics and stability of trypsin preparations were investigated. The relative activity of immobilized trypsin was 122.9% when the enzyme was immobilized adsorptively in the MCFs. Trypsin assembled with BSA in the MCFs attained maximum specific activity, 1.33 times that of the unmodified immobilized trypsin. The K-m value of the BSA derivative of trypsin was reduced to 15.9% and 16.6% relative to the valve for native and solely immobilized trypsin, respectively, while the K-cat/K-m value of trypsin assembled with BSA was enhanced to 148%. The residual activity of trypsin assembled with BSA was 48.5% and 29.4% at 50 degrees C and 60 degrees C, respectively, after incubation for 60 min.