Thermal deactivation of an α-amylase from Bacillus licheniformis.

We have experimentally studied the enzymatic hydrolysis of 1g/l soluble starch with alpha-amylases from Bacillus licheniformis (using the commercial enzyme Termamyl 300 L Type DX) under routine operation conditions of washing with detergents containing enzymes (pH = 7.5 and T = 65degreesC). To monitor the enzymatic reaction, we developed a procedure based on the iodometric method of measuring amylase activity. It was found that using the same treatment intensity, testing different enzyme concentrations and reaction times, resulted in practically the same conversion, while this changed when maintaining the enzyme solution at 65degreesC for different previous times before the reaction. Therefore thermal denaturing of the enzyme follows a second-order kinetic. A procedure for calculating the deactivation constant was established, which considers both the experiments made at different previous times as well as those corresponding to different treatment intensities, obtaining a k(d) value of 38.9 (g/l(.)min)(-1).