Immobilization of Papain on Siliceous Mesocellular Foam

Siliceous mesocellular foam (MCF) was employed as carriers in the immobilization of papain, and the properties and the stabilities of the immobilized enzyme were investigated in detail. The results show that the amount of papain immobilized on MCF material reaches 334 mg/g MCF. The optimal pH and reaction temperature of the immobilized papain are 7.5 and 50 degrees C, respectively. The Michaelis constant (Km) of immobilized papain is disclosed as 6.99 x 10(-3)mol/L by the Lineweaver-Burk plot at 37 degrees C. The immobilized papain with 65.1% of the activity remaines after repeating the catalysis of casein for 8 times. After stored at 4 degrees C for 60d, the immobilized papain retaines 75% of the activity, while the free papain only retains 53.6%. The pH, thermal, operational, storage stabilities of the immobilized enzyme are improved due to the large pore microenvironment and the shield of the mesopores of MCF, which can be considered as excellent supports for papain immobilization.