Stabilization of Bacillus Licheniformis ATCC 21415 Alkaline Protease by Immobilization and Modification

Alkaline protease from Bacillus licheniformis ATCC21415 was partially purified by fractional precipitation at 70% ethanol which showed 6.2-fold purification. Immobilization of the enzyme by physical adsorption on loofa (as a new carrier) had the highest immobilization yield (70.5%).Chemical modification of the enzyme by covalent coupling with sodium -periodate activated amylopectin retained (78.3%) of the original activity. Immobilized and modified enzymes retained 59.9 and 76.1%, respectively of the original activity after heating at 60 C for 60 min while the native o 1/2 enzyme retained 19.4%. The calculated half-life values (t ) of heat inactivation at 60 C for modified, o A immobilized and native protease were 115 , 100and 25 min, respectively. Activation energy (E ) of the native enzyme was 23.6Kcal/mol which higher than those of immobilized and modified enzymes max (18.9 and 19.9Kcal/mol, respectively). The immobilized and modified forms exhibited lower V and m higher K values compared to that of the native form. Immobilized and modified forms were more stable in presence of EDTA than the native form. The crude enzyme digested some natural proteins and was able to extract collagen from chicken skin.