Partial Purification and Characterization of a Heat Stable α-Amylase from a Thermophilic Actinobacteria, Streptomyces sp. MSC702.

A partial purification and biochemical characterization of the α-amylase from Streptomyces sp. MSC702 were carried out in this study. The optimum operational conditions for enzyme substrate reaction for amylolytic enzyme activity from the strain were evaluated. The optimum pH, temperature, and incubation period for assaying the enzyme were observed to be 5.0, 55°C, and 30 min, respectively. The extracellular extract was concentrated using ammoniumsulfate precipitation. It was stable in the presence of metal ions (5mM) such as K⁺, Co²⁺, and Mo²⁺, whereas Pb²⁺, Mn²⁺, Mg²⁺, Cu²⁺, Zn²⁺, Ba²⁺, Ca²⁺, Hg²⁺, Sn²⁺, Cr³⁺, Al³⁺, Ag⁺, and Fe²⁺ were found to have inhibitory effects. The enzyme activity was also unstable in the presence of 1% Triton X-100, 1% Tween 80, 5mM sodium lauryl sulphate, 1% glycerol, 5mM EDTA, and 5mM denaturant urea. At temperature 60°C and pH 5.0, the enzyme stability wasmaximum. α-amylase retained 100% and 34.18% stability for 1 h and 4 h, respectively, at 60°C (pH 7.0). The enzyme exhibited a half-life of 195 min at 60°C temperature. The analysis of kinetic showed that the enzyme has K_m of 2.4mg/mL and V_max of 21853.0 µmol/min/mg for soluble potato starch. The results indicate that the enzyme reflects their potentiality towards industrial utilization. [ABSTRACT FROM AUTHOR]