Effect of energy-gathered ultrasound on Alcalase

This research was to explore the mechanism of ultrasonic impact on protease activity. The effects of energy-gathered ultrasound on the activity, kinetics, thermodynamics and molecular structure of Alcalase were investigated with the aid of the chemical reaction kinetics model, Arrhenius equation, Eyring transition state theory, fluorescence spectroscopy and circular dichroism (CD) spectroscopy. Results showed that ultrasound had effect on the activity of Alcalase. The highest Alcalase activity was achieved when the sample was treated with energy-gathered ultrasound at 80 W for 4 min, under which the enzyme activity was increased by 5.8% over the control. After the treatment, thermodynamics parameters Ea, Delta H, Delta S and Delta G were reduced by 70.0%, 75.8%, 34.0% and 1.3%, respectively. Besides, fluorescence and CD spectra revealed that the ultrasonic treatment had increased the number of tryptophan on Alcalase surface slightly, increased number of alpha-helix by 5.2%, and reduced the number of random coil by 13.6%. (C) 2010 Elsevier B.V. All rights reserved.