Immobilization and Characterization of an alkaline Protease from Aspergillus niger
Pages : 925-929Download PDF
A protease is an enzyme that performs proteolysis that begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein. Proteases are the single class of enzyme which occupies a pivotal position with respect to their applications in both physiological and commercial fields. Aspergillus niger was selected for production, partial purification and characterization with various process parameters. In specific media containing Casein (1%) maximum production of free enzyme was observed at pH of 8.5 and temperature of 50oC. The optimum pH and temperature for the assay of immobilized protease was 9.0 and 55oC. The enzyme was partially purified using 40% ammonium sulphate precipitation followed by dialysis. A gradual decrease in the activity of the free and the immobilized protease was observed when the temperature was increased beyond their optimum temperature. A gradual decrease in the activity of the free protease was observed when the pH was increased beyond their optimum pH. The maximum activity range of immobilized enzyme over pH 8.5-9.0 revealed its resistance to alkaline changes in the medium as compared to free enzyme. There was increase in activity of the free and the immobilized protease as the concentration of casein was increasing at certain point after that, it reaches the saturation point and remains constant. Immobilized enzyme preparation had retained almost 33.6% activity after 4th Cycle.
Keywords: Alkaline Protease, Ammonium sulphate precipitation, Immobilization.