Characterization of α- Amylase Produced from a Local Isolate of Bacillus licheniformis R5

This research is conducted at the College of Agriculture, University of Baghdad in 2004. The characterization of the purified enzyme shows that the molecular weight of the enzyme produced from the bacteria is 56.000 Daltons as it was determined by gel filtration on Sephacryl S- 200 column and the pH of the enzyme activity is 8.0 but the enzyme is more stable at pH range between 7.0 – 9.0, also the optimum temperature of the enzyme activity was 50°C at the optimum pH stability. The activation energy of the converted substrate (starch) of products was 17.500 cal mole while the activation energy of the denaturized enzyme is 64.000 cal mole. The Kinetic studies show that the Michaels constant (Km) values of the enzyme using starch, glycogen and amylose as substrates are 0.44 mM, 0.43 mM and 0.28 mM respectively, revealing that the enzyme has a highest affinity to amylose in comparison with starch and glycogen , It was also found that the addition of calcium chloride to the reaction mixture increase the enzyme activity by 138.8% (Conc. of 0.6 mM) , also by measuring the thermo stability of the enzyme in the presence of calcium chloride with a concentration of (0.6 mM and 1.0mM) at (70 – 80)°C , the enzyme has kept its total activity at 70°C and 95.3% of its activity in the presence of 0.6 mM of calcium chloride and 100% in the presence of 1.0 mM at 80°C