Immobilization of papain on mesoporous silica: pH effect

The enzyme papain was adsorbed on mesoporous silica at 4°C and pH values between 3 and 11. From the adsorption kinetic data, the rate constant for the process was evaluated. The concentration of the enzyme in solution was calculated by monitoring the absorbance at 280 nm, and the quantity of papain bound to the solid was evaluated from the initial and residual soluble enzyme concentrations. The best results were observed for papain adsorption at pH 5.0; under these conditions, the desorption of the enzyme was <5%.