Purification and characterization of α-amylase from Bacillus amyloliquefaciens NCIM 2829

Abstract

α-Amylase (EC 3.2.1.1) was purified to homogeneity (specific activity 58,000 μmole min -1 mg protein -1) from the culture filtrate of Bacillus amyloliquefaciens NCIM 2829. Its molecular mass was found to be 67.5 kDa. The activity of the enzyme increased by almost 50% in the presence of Co +2 ion. Hg 2+ and Cu 2+ acted as strong inhibitors of the enzyme. The tryptophan moities of the enzyme were fairly protected from the aqueous environment. However, the globular interior of the protein was somewhat loosely packed. The protein had nearly an equal amount of α-helical and β-sheet structure in dilute solution. In concentrated solution, its secondary structure had a higher proportion of β-sheet at the expense of some random coil structure. The protein showed a molten globule state at a low concentration of chaotropic agent. The denaturation profile of the protein showed no cooperativity. Co 2+ enhanced the structural stability of the enzyme.