Preparation and properties of immobilized papain and lipase

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Abstract
Papain and lipase were immobilized on derivatized Sepharose 4-B. The activated agarose had a binding capacity of 1.2 μmol amino groups/ml packed agarose or 17 mg proteins/g dry agarose. The immobilized enzyme preparations were tested for the effects of pH of assay, temperature of assay, and substrate concentrations. The effect of 6M urea on the activity of papain was also determined. Soluble forms of the enzymes were used for comparison. Immobilization of the enzymes resulted in slightly different pH and temperature optima for activities. For immobilized papain Km (app) was similar to the one observed with soluble papain. Immobilization of lipase, however, caused a decrease in Km values. The immobilized enzyme preparations were stable when stored at 4°C and pH 7.5 for periods up to eight months. The soluble enzymes lost their activity within 96 hr under similar storage conditions. Immobilized papain did not lose any activity after treatment with 6M urea for 270 min, whereas soluble papain lost 81% of its activity after the urea treatment, indicating that the immobilization of papain imparted structural and conformational stability to this enzyme.