Sonochemical Effect on Activity and Conformation of Commercial Lipases

Ultrasonic reactor set-ups and applications: A review

Sonochemistry contributes to green science as it uses less hazardous solvents and methods to carry out a reaction. In this review, different reactor designs are discussed in detail providing the necessary knowledge for implementing various processes. The main characteristics of ultrasonic batch systems are their low cost and enhanced mixing; however, they still have immense drawbacks such as their scalability. Continuous flow reactors offer enhanced production yields as the limited cognition which governs the design of these sonoreactors, renders them unusable in industry. In addition, microstructured sonoreactors show improved heat and mass transfer phenomena due to their small size but suffer though from clogging. The optimisation of various conditions of regulations, such as temperature, frequency of ultrasound, intensity of irradiation, sonication time, pressure amplitude and reactor design, it is also discussed to maximise the production rates and yields of reactions taking place in sonoreactors. The optimisation of operating parameters and the selection of the reactor system must be considered to each application's requirements. A plethora of different applications that ultrasound waves can be implemented are in the biochemical and petrochemical engineering, the chemical synthesis of materials, the crystallisation of organic and inorganic substances, the wastewater treatment, the extraction processes and in medicine. Sonochemistry must overcome challenges that consider the scalability of processes and its embodiment into commercial applications, through extensive studies for understanding the designs and the development of computational tools to implement timesaving and efficient theoretical studies.

Impact of non-thermal techniques on enzyme modifications for their applications in food

The present review elaborates on the details of the enzyme, its structure, specificity, and the mechanism of action of selected enzymes as well as structural changes and loss or gain of activity after non-thermal treatments for food-based applications. Enzymes are biological catalysts found in various systems such as plants, animals, and microorganisms. Most of the enzymes have their optimum pH, temperature, and substrate or group of substrates. The conformational modification of enzymes either increases or decreases the rate of reaction at different pH, and temperature conditions. Enzymes are modified by different techniques to enhance the activity of enzymes for their commercial applications mainly due to the high cost of enzymes, stability, and difficulties that occur during the use of enzymes in different conditions. On the opposite, enzyme inactivation provides its application to extend the shelf life of fruits and vegetables by denaturation and partial inactivation of enzymes. Hence, the activation and inactivation of enzymes are studied by non-thermal techniques in both the model and the food system. The highly reactive species generated during non-thermal techniques cause chemical and structural modification. The enzyme modifications depend on the type and source of the enzyme, type of technique, and the parameters used.

The cellular response and molecular mechanism of superoxide dismutase interacting with superparamagnetic iron oxide nanoparticles

This study explored the response of superoxide dismutase (SOD) under superparamagnetic iron oxide nanoparticles (SPIONs)-induced oxidative stress using combined cellular and molecular methods. Results found that SPIONs induced the inhibition of catalase activity, the U-inverted change of SOD activity and the accumulation of reactive oxygen species (ROS), leading to oxidative damage and cytotoxicity. The change of intracellular SOD activity was resulted from the increase of molecular activity induced by directly interacting with SPIONs and ROS-inhibition of activity. The increase of molecular activity could be attributed to the structural and conformational changes of SOD, which were caused by the direct interaction of SOD with SPIONs. The SOD-SPIONs interaction and its interacting mechanism were explored by multi-spectroscopy, isothermal titration calorimetry and zeta potential assays. SOD binds to SPIONs majorly via hydrophobic forces with the involvement of electrostatic forces. SPIONs approximately adsorb 11 units of SOD molecule with the binding affinity of 2.99 × 106 M-1. The binding sites on SOD were located around Tyr residues, whose hydrophilicity increased upon interacting with SPIONs. The binding to SPIONs loosened the peptide chains, changed the secondary structure and reduced the aggregation state of SOD.

Enhancing efficiency of ultrasound-assisted biodiesel production catalyzed by Eversa® Transform 2.0 at low lipase concentration: Enzyme characterization and process optimization

This study focused on the ultrasound-assisted transesterification of simulated low-quality feedstocks using a low-cost liquid lipase Eversa® Transform 2.0 (ET2). Enzyme characterization was also performed to investigate the effect of ultrasound parameters on enzyme structure. The optimal ultrasound parameters, 40 % amplitude, and 5 % duty cycle effectively enhanced the reaction rate compared to the conventional stirring method while retaining 95 % of the enzyme activity. Analysis of circular dichroism (CD) spectra revealed the preservation of the secondary structure of ET2 under the optimal ultrasound intensities, while fluorescence spectra indicated a slight change in its tertiary structure. The implementation of a two-stage methanol dosing strategy in the ultrasound-assisted reaction effectively mitigated lipase inhibition, yielding a remarkable fatty acid methyl ester (FAME) content of 92.2 % achieved within a 12-h reaction time. Notable, this high FAME content was achieved with only a 4:1 methanol-to-oil molar ratio and a 0.5 wt% enzyme concentration. Under these optimized conditions, the ultrasound-assisted reaction also demonstrated a 15 % improvement in the final FAME content compared to the conventional stirring method. These promising results hold significant potential for advancing the field of biodiesel production via ultrasound technology, contributing substantively to sustainable energy sources.

Enhancement of enzyme activity by laser-induced energy propulsion of upconverting nanoparticles under near-infrared light: A comprehensive methodology for in vitro and in vivo applications

If the appropriate immobilization method and carrier support are not selected, partial decreases in the activity of enzymes may occur after immobilization. Herein, to overcome this challenge, an excitation mechanism that enables energy transfer was proposed. Modified upconverting nanoparticles (UCNPs) were constructed and the important role of near-infrared (NIR) excitation in enhancing the catalytic activity of the enzyme was demonstrated. For this purpose, UCNPs were first synthesized via the hydrothermal method, functionalized with isocyanate groups, and then, PEG-L-ASNase was immobilized via covalent binding. UCNPs with and without PEG-L-ASNase were extensively characterized by different methods. These supports had immobilization yield and activity efficiency of >96 % and 78 %, respectively. Moreover, immobilized enzymes exhibited improved pH, thermal, and storage stability. In addition, they retained >65 % of their initial activity even after 20 catalytic cycles. Biochemical and histological findings did not indicate a trend of toxicity in rats due to UCNPs. Most importantly, PEG-L-ASNase activity was triggered approximately 5- and 2-fold under in vitro and in vivo conditions, respectively. Overall, it is anticipated that this pioneering work will shed new light on the realistic and promising usage of NIR-excited UCNPs for the immobilization of enzymes in expensive and extensive applications.

Influence of Supercritical Carbon Dioxide on the Activity and Conformational Changes of α-Amylase, Lipase, and Peroxidase in the Solid State Using White Wheat Flour as an Example

Green technologies using renewable and alternative sources, including supercritical carbon dioxide (sc-CO2), are becoming a priority for researchers in a variety of fields, including the control of enzyme activity which, among other applications, is extremely important in the food industry. Namely, extending shelf life of e.g., flour could be reached by tuning the present enzymes activity. In this study, the effect of different sc-CO2 conditions such as temperature (35-50 °C), pressure (200 bar and 300 bar), and exposure time (1-6 h) on the inactivation and structural changes of α-amylase, lipase, and horseradish peroxidase (POD) from white wheat flour and native enzymes was investigated. The total protein (TPC) content and residual activities of the enzymes were determined by standard spectrophotometric methods, while the changes in the secondary structures of the enzymes were determined by circular dichroism spectrometry (CD). The present work is therefore concerned for the first time with the study of the stability and structural changes of the enzyme molecules dominant in white wheat flour under sc-CO2 conditions at different pressures and temperatures. In addition, the changes in aggregation or dissociation of the enzyme molecules were investigated based on the changes in particle size distribution and ζ-potential. The results of the activity assays showed a decrease in the activity of native POD and lipase under optimal exposure conditions (6 h and 50 °C; and 1 h and 50 °C) by 22% and 16%, respectively. In contrast, no significant changes were observed in α-amylase activity. Consequently, analysis of the CD spectra of POD and lipase confirmed a significant effect on secondary structure damage (changes in α-helix, β-sheet, and β-turn content), whereas the secondary structure of α-amylase retained its original configuration. Moreover, the changes in particle size distribution and ζ-potential showed a significant effect of sc-CO2 treatment on the aggregation and dissociation of the selected enzymes. The results of this study confirm that sc-CO2 technology can be effectively used as an environmentally friendly technology to control the activity of major flour enzymes by altering their structures.

Ultrasound-Assisted Enzymatic Protein Hydrolysis in Food Processing: Mechanism and Parameters

Ultrasound has been widely used as a green and efficient non-thermal processing technique to assist with enzymatic hydrolysis. Compared with traditional enzymatic hydrolysis, ultrasonic-pretreatment-assisted enzymatic hydrolysis can significantly improve the efficiency of enzymatic hydrolysis and enhance the biological activity of substrates. At present, this technology is mainly used for the extraction of bioactive substances and the degradation of biological macromolecules. This review is focused on the mechanism of enzymatic hydrolysis assisted by ultrasonic pretreatment, including the effects of ultrasonic pretreatment on the enzyme structure, substrate structure, enzymatic hydrolysis kinetics, and thermodynamics and the effects of the ultrasonic conditions on the enzymatic hydrolysis results. The development status of ultrasonic devices and the application of ultrasonic-assisted enzymatic hydrolysis in the food industry are briefly described in this study. In the future, more attention should be paid to research on ultrasound-assisted enzymatic hydrolysis devices to promote the expansion of production and improve production efficiency.

Green light enhanced the photostability and catalytic performance of fatty acid photodecarboxylase

Green light was documented to improve the photostability of fatty acid photodecarboxylase from Chlorella variabilis (CvFAP). Compared to blue light, green light increased the pentadecane yield by 27.6% and improved the residual activity of CvFAP to 5.9-fold after the preillumination. Kinetics and thermodynamics indicated that blue light facilitated a high CvFAP activity.

Sono-activation of food enzymes: From principles to practice

Over the last decade, sono-activation of enzymes as an emerging research area has received considerable attention from food researchers. This kind of relatively new application of ultrasound has demonstrated promising potential in facilitating the modern food industry by broadening the application of various food enzymes, improving relevant industrial unit operation and productivity, as well as increasing the yield of target products. This review aims to provide insight into the fundamental principles and possible industrialization strategies of the sono-activation of food enzymes to facilitate its commercialization. This review first provides an overview of ultrasound application in the activation of food protease, carbohydrase, and lipase. Then, the recent development on ultrasound activation of food enzymes is discussed on aspects including mechanisms, influencing factors, modification effects, and its applications in real food systems for free and immobilized enzymes. Despite the far fewer studies on sono-activation of immobilized enzymes compared with those on free enzymes, we endeavored to summarize the relevant aspects in three stages: ultrasound pretreatment of free enzyme/carrier, assistance in immobilization process, and modification of the already immobilized enzyme. Lastly, challenges for the scalability of ultrasound in these target areas are discussed and future research prospects are proposed.

Amphiphilic Nanointerface: Inducing the Interfacial Activation for Lipase

Graphene-based materials are widely used in the field of immobilized enzymes due to their easily tunable interfacial properties. We designed amphiphilic nanobiological interfaces between graphene oxide (GO) and lipase TL (Thermomyces lanuginosus) with tunable reduction degrees through molecular dynamics simulations and a facile chemical modulation, thus revealing the optimal interface for the interfacial activation of lipase TL and addressing the weakness of lipase TL, which exhibits weak catalytic activity due to an inconspicuous active site lid. It was demonstrated that the reduced graphene oxide (rGO) after 4 h of ascorbic acid reduction could boost the relative enzyme activity of lipase TL to reach 208%, which was 48% higher than the pristine GO and 120% higher than the rGO after 48 h of reduction. Moreover, TL-GO-4 h's tolerance against heat, organic solvent, and long-term storage environment was higher than that of free TL. The drawbacks of strong hydrophobic nanomaterials on lipase production were explored in depth with the help of molecular dynamics simulations, which explained the mechanism of enzyme activity enhancement. We demonstrated that nanomaterials with certain hydrophilicity could facilitate the lipase to undergo interfacial activation and improve its stability and protein loading rate, displaying the potential of the extensive application.

Process study of ceramic membrane-coupled mixed-cell fermentation for the production of adenine

In order to solve the problems of high complexity, many by-products, high pollution and difficult extraction of the existing adenine production process, in this study, ceramic membrane-coupled mixed cell fermentation was used to produce adenine while reducing the synthesis of by-products and simplifying the production process of adenine. Nucleoside hydrolase (encoded by the rihC gene) was used to produce adenine by coordinated fermentation with the adenosine-producing bacterium Bacillus Subtilis XGL. The adenosine hydrolase (AdHy)-expressing strain Escherichia coli BL21-AdHy was successfully employed and the highest activity of the crude enzyme solution was found by orthogonal experiments at 170 W power, 42% duty cycle, and 8 min of sonication. The highest AdHy activity was found after 18 h of induction incubation. E. coli BL21-AdHy was induced for 18 h and sonicated under the above ultrasonic conditions and the resulting crude enzyme solution was used for co-fermentation of the strain and enzyme. Moreover, 15% (v/v) of the AdHy crude enzyme solution was added to fermentation of B. subtilis XGL after 35 h. Finally, the whole fermentation system was dialyzed using coupled ceramic membranes for 45 and 75 h, followed by the addition of fresh medium. In contrast, the AdHy crude enzyme solution was added after 35, 65, and 90 h of B. subtilis fermentation, with three additions of 15, 15, and 10% of the B. subtilis XGL fermentation system. The process was validated in a 5 L fermenter and 14 ± 0.25 g/L of adenine was obtained, with no accumulation of adenosine and d-ribose as by-products. The enzymatic activity of the AdHy crude solution treated with ultrasound was greatly improved. It also reduced the cellular activity of E. coli BL21-AdHy and reduced effects on bacterial co-fermentation. Membrane-coupled dialysis solved the problem of decreased yield due to poor bacterial survival and decreased viability, and eliminated inhibition of the product synthesis pathway by adenosine. The batch addition of crude enzyme broth allowed the continuous conversion of adenosine to adenine. This production method provides the highest yield of biologically produced adenine reported to date, reduces the cost of adenine production, and has positive implications for the industrial production of adenine by fermentation. And it provides a reference for producing other high-value-added products made by fermentation.

Ultrasound enhanced butyric acid-lauric acid designer lipid synthesis: Based on artificial neural network and changes in enzymatic structure

Ultrasound is a green technology for intensifying enzymatic reactions. In this study, an ultrasonic water bath with equipment parameters of 28 kHz, 1750.1 W/m², 60% duty cycle was used to assist the synthesis of butyric acid-lauric acid designer lipid (BLDL), which was catalyzed by Lipozyme 435. A convincing three-layer feed-forward artificial neural network (ANN) model was established (R² = 0.949, RMSE = 4.759, ADD = 7.329) to accurately predict the optimal parameters combination, which was described as 13.72 mL reaction volume, 15.49% enzyme loading, 0.253 substrate molar ratio (tributyrin/lauric acid), 56.58 °C reaction temperature and 120 min reaction time. The ultrasonic assistance increased actual butyric acid conversion rate by 11.38%, and also enhanced the consumption rate of tributyrin and lauric acid during the reaction. Meanwhile, the esterification activity of Lipozyme 435 was enhanced and its effectiveness up to 6 cycles. Structurally, ultrasound assistance significantly disrupted the secondary structure of the Lipozyme 435: reduced the content of α-helices, increased the content of β-sheet and β-turn. In addition, sonication caused an increase in crevice and micro-damage on the surface of the immobilized enzyme. In conclusion, low-intensity ultrasound at 28 kHz improved the synthesis efficiency of BLDL, which was scientifically predicted by ANN model, and the change of enzyme structure may be the vital reason for ultrasound enhanced reaction. However, the effect of ultrasound on immobilized enzymes' activity needs to be further explored.

Ultrasound for pectinase modification: an investigation into potential mechanisms

BACKGROUND

Today, ultrasound is increasingly utilized in enzyme modification. Strongly dependent on the specific operational conditions, the modification effect brought by ultrasound can be activation and inactivation of enzymes. This work aims to study the ultrasound mechanisms under different conditions, to investigate the respective roles of free radical effect and mechanical effect in pectinase activation and inactivation, and to reveal the influence of pectinase concentration on the ultrasound-modification effect.

RESULTS

When ultrasound was introduced to a liquid system, generation of free radicals was positively correlated with ultrasound intensity and treatment duration, but negatively correlated with temperature. Thiourea with a concentration of 4 mmol L^-1 was selected as a free radical scavenger to effectively shield ultrasound free radicals. The highest enzyme activity of pectinase solutions at 0.1, 1.0, and 10.0 mg mL^-1 was obtained at the same ultrasound intensity of 4.50 W mL^-1 and time of 15 min, where the enzyme activity was increased by 68.24%, 20.98% and 18.83%, respectively. Furthermore, the addition of thiourea enhanced the enzyme activity at each tested ultrasound intensity and time, especially those exceeding the best conditions; it also eliminated the redshift phenomenon that was previously presented in the fluorescence spectra of pectinase samples.

CONCLUSION

Pectinase concentrations did not change the optimum ultrasound conditions for enzyme modification, but pectinase with a low concentration was more vulnerable to ultrasound treatment. During modification, ultrasound mechanical effects dominated in the pectinase activation, while free radical effects dominated in the inactivation process. © 2020 Society of Chemical Industry.

Lipase activation by molecular bioimprinting: The role of interactions between fatty acids and enzyme active site

Bioimprinting is an easy, sustainable and low-cost technique that promotes a printing of potential substrates on enzyme structure, inducing a more selective and stable conformation. Bioimprinting promotes conformational changes in enzymes, resulting in better catalytic performance. In this work, the effect of bioimprinting of Burkholderia cepacia lipase (BCL) and porcine pancreatic extracts (PPE) with four different fatty acids (lauric acid (C12:0), myristic acid (C14:0), palmitic acid (C16:0), and stearic acid (C18:0)) was investigated. The results demonstrated that the better bioimprinting effect was in BCL with lauric acid in esterification reaction, promoting BCL activation in which relative enzyme activity was 70 times greater than nonimprinted BCL. Bioimprinting results were influenced by the carbon chain length of fatty acids imprinted in the BCL, in which the effects were weaker with the chain increase. Molecular docking was performed to better understand the bioimprinting method. The results of these simulations showed that indeed all fatty acids were imprinted in the active site of BCL. However, lauric acid presented the highest imprinting preference in the active site of BCL, resulting in the highest relative activity. Furthermore, Fourier transform infrared (FTIR) analysis confirmed important variations in secondary structure of bioimprinting BCL with lauric acid, in which there was a reduction in the α-helix content and an increase in the β-sheet content that facilitated substrate access to the active site of BCL and led higher rigidity, resulting in high activity. Bioimprinted BCL with lauric acid showed excellent operational stability in esterification reaction, maintaining its original relative activity after five successive cycles. Thus, the results show that bioimprinting of BCL with lauric acid is a successful strategy due to its high catalytic activity and reusability.

Low-frequency Ultrasound with Short Application Time Improves Cellulase Activity and Reducing Sugars Release

In this study, we investigated the effect of ultrasound (US) on the activity of commercial cellulase (Celluclast® 1.5 L) in the absence and in the presence of a cellulosic substrate (Avicel®, 2% w.v^-1) using a central composite rotatable design. Sonication time (10 to 330 s), US intensity (120.6 to 263.7 W cm^-2), and reaction temperature (25 to 50 °C) were varied using a horn-type ultrasound reactor, and endoglucanase (CMCase) and total cellulase (FPase) activities were determined. US intensity had a positive effect on enzyme activity. Under optimal conditions (170 s, 180.8 W cm^-2, and 25 °C), CMCase activity was 13% higher than that of the control. In the presence of substrate, CMCase activity increased by 33.87% and K_M reduced by 23% in relation to that of the control. The theoretical yield of cellulose was 42.08%. Cellulase activity can be improved by US treatment to maximize productivity gains and reduce costs in second-generation ethanol production, by the action of a low-frequency ultrasound with a short ultrasonication time of application.

Continuous flow reactor based with an immobilized biocatalyst for the continuous enzymatic transesterification of crude coconut oil

Here, we have assessed the use of one packed bed or two packed bed reactors in series in which Burkholderia cepacia lipase (BCL) was immobilized on protic ionic liquid (PIL)-modified silica and used as a biocatalyst for the transesterification of crude coconut oil. Reaction parameters including volumetric flow, temperature, and molar ratio were evaluated. The conversion of transesterification reaction products (ethyl esters) was determined using gas chromatography and the quantities of intermediate products (diglyceride and monoglyceride [MG]) were assessed using high-performance liquid chromatography. Packed bed reactors in series produced ethyl esters with the greatest efficiency, achieving 65.27% conversion after 96 H at a volumetric flow rate of 0.50 mL Min^-1 at 40 °C and a 1:9 molar ratio of oil to ethanol. Further, within the first 24 H of the reaction, increased MG (54.5%) production was observed. Molecular docking analyses were performed to evaluate the catalytic step of coconut oil transesterification in the presence of BCL. Molecular docking analysis showed that triglycerides have a higher affinity energy (-5.7 kcal mol^-1 ) than the smallest MG (-6.0 kcal mol^-1 ), therefore, BCL catalyzes the conversion of triglycerides rather than MG, which is consistent with experimental results.

Fruit Seeds as Sources of Bioactive Compounds: Sustainable Production of High Value-Added Ingredients from By-Products within Circular Economy

The circular economy is an umbrella concept that applies different mechanisms aiming to minimize waste generation, thus decoupling economic growth from natural resources. Each year, an estimated one-third of all food produced is wasted; this is equivalent to 1.3 billion tons of food, which is worth around US$1 trillion or even $2.6 trillion when social and economic costs are included. In the fruit and vegetable sector, 45% of the total produced amount is lost in the production (post-harvest, processing, and distribution) and consumption chains. Therefore, it is necessary to find new technological and environmentally friendly solutions to utilize fruit wastes as new raw materials to develop and scale up the production of high value-added products and ingredients. Considering that the production and consumption of fruits has increased in the last years and following the need to find the sustainable use of different fruit side streams, this work aimed to describe the chemical composition and bioactivity of different fruit seeds consumed worldwide. A comprehensive focus is given on the extraction techniques of water-soluble and lipophilic compounds and in vitro/in vivo functionalities, and the link between chemical composition and observed activity is holistically explained.

One pot synthesis of α-amylase metal organic framework (MOF)-sponge via dip-coating technique

Enzyme embedded metal-organic frameworks (MOFs) are blooming in the field of enzyme immobilization on account of their superior catalytic efficiency, thermal and chemical stability as compared to native enzyme. However, the separation and recovery of enzyme embedded MOF composite is quite challenging due to its nanometer size, high dispersity and low density which limits the reusability. In this work, α-amylase embedded zeolite imidazole framework (ZIF)-67 was fabricated onto melamine sponge using surfactant assisted dip coating technique. This was achieved in single pot making the method facile and rapid. α-Amylase MOF-sponge was analysed and characterized by FT-IR, XRD, SEM and TGA. We demonstrated that the encapsulation could maintain the active conformational structure of α-amylase after immobilization procedure with excellent bioactivity. Further, apart from merits of framework shielding, it offers mass transfer limitation for macromolecular substrate (like starch) which was determined and expressed as effectiveness factor (η) by using Michaelis-Menten enzyme kinetics. At the end, recycling studies were carried out for α-amylase MOF-sponge which showed 32% residual activity after six consecutive cycles. It is believed that this strategy has great potential in the field of continuous biotransformation (catalysis), biosensing and biomedicine application.

Interaction of a digestive protease, Candida rugosa lipase, with three surfactants investigated by spectroscopy, molecular docking and enzyme activity assay

The extensive use of surfactants in food, laundry products and agriculture has caused concern about their biosafety. However, few studies have been done on their potential effect on the lipase which has always been used with surfactants in food and laundry industry. Herein, we investigated the interaction of three surfactants (sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), sodium lauryl sulfonate (SLS)) with Candida rugosa lipase (CRL), which is a popular biocatalyst used regularly with surfactants. The effect of the three surfactants on the conformation and activity of CRL was evaluated by using multiple spectral methods, enzyme activity assay and molecular docking modeling. The results demonstrated that CRL interacted with SDS, SDBS and SLS primarily through hydrophobic forces, H-bonding and electrostatic forces, respectively. The binding constants (K_A) of SDBS with CRL varied with temperature: 1.99×10³mol/L at 298K and 4.13×10³mol/L at 318K. SDS and SDBS affected the secondary structure and skeleton of CRL, which changed the polarity of CRL and enhanced its activity. SLS also changed the secondary structure and activity of CRL moderately, but had little effect on its polarity and chromophore microenvironment. Accordingly, all three surfactants exhibited effect to CRL on the molecular level calling for more attention to pay on their biosafety. The work demonstrates that SDS, SDBS and SLS could cause negative effects to CRL from different angles and therefore are not bio-friendly detergents.

Ultrasound assisted intensification of enzyme activity and its properties: a mini-review

Over the last decade, ultrasound technique has emerged as the potential technology which shows large applications in food and biotechnology processes. Earlier, ultrasound has been employed as a method of enzyme inactivation but recently, it has been found that ultrasound does not inactivate all enzymes, particularly, under mild conditions. It has been shown that the use of ultrasonic treatment at appropriate frequencies and intensity levels can lead to enhanced enzyme activity due to favourable conformational changes in protein molecules without altering its structural integrity. The present review article gives an overview of influence of ultrasound irradiation parameters (intensity, duty cycle and frequency) and enzyme related factors (enzyme concentration, temperature and pH) on the catalytic activity of enzyme during ultrasound treatment. Also, it includes the effect of ultrasound on thermal kinetic parameters and Michaelis-Menten kinetic parameters (k_m and V_max) of enzymes. Further, in this review, the physical and chemical effects of ultrasound on enzyme have been correlated with thermodynamic parameters (enthalpy and entropy). Various techniques used for investigating the conformation changes in enzyme after sonication have been highlighted. At the end, different techniques of immobilization for ultrasound treated enzyme have been summarized.