Purification and biochemical characterization of α-amylase from Aspergillus tamarii MTCC5152

The purification and biochemical characterization of the extracellular alpha amylase from A.tamarii MTCC5152 were studied. The combined use of ion exchange and gel filtration chromatographic methods were used for purification studies. The specific activity was significantly increased (33 fold) and 19.41 fold purification of the enzyme alpha-amylase with 24% yield was achieved. The enzyme had an optimal pH of 6.5 and exhibited its highest activity at 55 degrees C. It is active over a wide range of pH 5-7 at room temperature. The enzyme is relatively stable in the temperature range of 25-35 degrees C for a period of 4 h hence, more suitable for industrial applications. K-m and V-max value of the enzyme was to be 5.882mg/mL and 0.803mg/mL/min respectively using starch as the substrate. The purified protein showed a single band on native and SDS PAGE and the molecular weight was found to be 31 kDa. Starch zymogram also revealed one clear zone of amylolytic activity which corresponded to the band obtained with native PAGE and SDS/PAGE. The characterization studies showed that the enzyme activity is inhibited by Ca2+, Mn2+, Hg2+, Fe2+.