Ultrasound-Assisted Intensification of Activity of Free and Immobilized Enzymes: A Review

Abstract

Ultrasound has shown considerable promise for various applications in food science and biotechnology. In the past, ultrasound has been used intensively to inactivate the enzyme, but today, ultrasound is also considered efficient to activate the enzyme by altering structural conformation under mild controlled conditions. The present review analyzes the governing mechanisms for intensification along with elucidating the effects of ultrasound parameters on enzyme activity. Different ultrasound parameters considered in the analysis include duty cycle, ultrasonic frequency, intensity/power, amplitude, and treatment time, whereas additional process parameters considered include temperature, pH, and enzyme concentration/nature of the medium. The review also provides a discussion on the effect of ultrasound on thermodynamic (activation energy, enthalpy, entropy, and free energy) and kinetic (V max , K m , and catalytic efficiency) parameters to highlight the changes in the design parameters. Results for the different spectroscopic techniques such as circular dichroism and fluorescence spectroscopy have also been described to examine the alteration in structural configuration for free and immobilized enzymes after treatment with ultrasound. Overall, this review has conclusively demonstrated that ultrasonic treatment shows an increase in enzymatic activity under an optimized set of treatment conditions also leading to beneficial processing in enzyme-based applications.

Is enzyme immobilization a mature discipline? Some critical considerations to capitalize on the benefits of immobilization

“…However, the use of ultrasound has been reported to permit agitation even inside the biocatalyst particles. [343][344][345][346][347][348] When the mass transfer is slower than the reaction rate, substrate and product concentration gradients are developed inside the biocatalyst particle, resulting in the enzyme located in the core of the biocatalyst particle catalyzing the reaction under conditions far from the ones set and monitored in the liquid phase (Fig. 9A).…”

“…However, the use of ultrasound has been reported to permit agitation even inside the biocatalyst particles. 343–348…”

Ultrasound-Assisted Intensification of β-Glucosidase Enzyme Activity in Free and Immobilized Forms

“…The successive cycles at definite intensity cause different stages of cavitation including generation of a cavity, its growth, and final intense collapse. Ultrasonic waves pass into a medium through transducers that convert electrical energy into vibrational energy, which directly influences the medium and leads to energy dissipation as heat or energy transfer for net transformations via cavitation events . The effect of ultrasound in different applications is based on the cavitation phenomenon.…”

“…Ultrasound also enhances the rate of mass transfer so that excellent catalytic efficiency can be achieved. Ultrasound makes changes in enzyme structures by periodic pressure fluctuation and controlling the characteristics of proteins . Mainly the physical (high pressure and turbulence) effects caused by ultrasound promote alteration in the enzyme structure, which leads to a change in enzyme activity .…”

Engineering Mussel-Inspired Coating on Membranes for Green Enzyme Immobilization and Hyperstable Reuse

“…In addition, enzymatic reactions are environmentally friendly, which generate nearly no toxic pollution with low energy consumption . Hence, enzymes play an important role in various fields, such as chemical production, cleaning, biosensing, micropollutant removal, and fouling control . Despite its superiority, the large-scale application of enzymes is confronted by low stability, which is attributed to the vulnerable spatial structure.…”