Effects of ultrasonication variables on the activity and properties of alpha amylase preparation

Recently, ultrasound was demonstrated to increase enzyme activity in food industry. In most studies, an enzyme-substrate mixture was ultrasonicated. Very little is reported on the ultrasonication of enzyme preparation; the effects of ultrasonication variables on the enzyme activity and properties remained unclear. In this study, an α-amylase preparation was ultrasonicated under different conditions. At the ultrasonic frequency, power, temperature, and time of 20 kHz, 25 W/mL, 30°C, and 75 s, respectively, the secondary structure of the α-amylase was changed and that improved the catalytic activity by 47% over the control. The optimal temperature and pH of the α-amylase preparation did not change under the ultrasonic treatment. In addition, ultrasonic treatment increased kinetic parameters of the α-amylase including maximal velocity Vmax , Michaelis constant Km , turnover number Kcat , and catalytic specificity constant Kcat /Km . Nevertheless, the ultrasonicated α-amylase had lower thermal inactivation rate constant and half-life value than the nonultrasonicated enzyme. Ultrasonic treatment can be considered as a novel solution for improvement in enzyme activity. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:702-710, 2018.