High pressure enhancement of enzymes: A review

Increased activity of alcohol oxidase at high hydrostatic pressure

Alcohol oxidase (AOx) from P. pastoris has potential applications in the production of carbonyl compounds and for the detection and quantification of alcohols. However, AOx's poor stability and low activity have hindered its practical application. There are two fractions of AOx in P. pastoris with different thermal stability. High hydrostatic pressure (HHP) increased the activity of the labile (L) + resistant (R) combined fractions but not of the R fraction alone. The activity of the L + R fractions increased 2.4-fold at 160 MPa and 30 °C compared to the activity at 0.1 MPa. At higher temperatures, the increase in activity with pressure was greater due to the combined stabilization and activation effects. The reaction rate of the R fraction at 50 °C was 17.9 ± 3.6 or 17.7 ± 0.8 μM min^-1 at 80 or 160 MPa, respectively, and was not significantly different from the activity of the L + R fractions under the same conditions (18.4 ± 2.7 μM min^-1). The activation energy of the R fraction was not significantly different between 80 MPa (41.5 ± 10.5 kJ mol^-1) and 160 MPa (43.8 ± 7.8 kJ mol^-1). The combined increase in the stability of the R fraction at HHP enables the use of the enzyme at 50 °C with little loss of activity and an increased catalytic rate.

Impact of high-pressure treatment on casein micelles, whey proteins, fat globules and enzymes activity in dairy products: a review

The quality and safety of food products are the two factors that most influence the demands made by consumers. Contractual food sterilization and preservation methods often result in unfavorable changes in functional properties of foods. High-pressure processing (HPP) (50-1000 MPa) is a non-thermal preservation technique, which can effectively reduce the activity of spoilage and pathogenic microorganisms with minimal impact on the functional and nutritional properties of food. Comprehensive inquires have disclosed the potential profits of HPP as an alternative to heat treatments by affecting the structure of milk components, particularly proteins and fats. The present paper aims to investigate the effects of HPP on milk components including fats, casein, whey proteins, enzymes, and minerals, as well as on the industrial production of milk and dairy products including cheese, yogurt, ice cream, butter, cream, and probiotic dairy products. HPP allows to extend shelf life of products without the use of additives, meeting current consumer demands. The assurance of microbial safety and the production of food products with minimal changes in quality characteristics (organoleptic, nutritional, and rheological properties) are among its main effects. In addition, the nutritional value of HPP-treated dairy products is also preserved.

Pressure tolerance of deep-sea enzymes can be evolved through increasing volume changes in protein transitions: a study with lactate dehydrogenases from abyssal and hadal fishes

We explore the principles of pressure tolerance in enzymes of deep-sea fishes using lactate dehydrogenases (LDH) as a case study. We compared the effects of pressure on the activities of LDH from hadal snailfishes Notoliparis kermadecensis and Pseudoliparis swirei with those from a shallow-adapted Liparis florae and an abyssal grenadier Coryphaenoides armatus. We then quantified the LDH content in muscle homogenates using mass-spectrometric determination of the LDH-specific conserved peptide LNLVQR. Existing theory suggests that adaptation to high pressure requires a decrease in volume changes in enzymatic catalysis. Accordingly, evolved pressure tolerance must be accompanied with an important reduction in the volume change associated with pressure-promoted alteration of enzymatic activity ( Δ V PP ∘ ). Our results suggest an important revision to this paradigm. Here, we describe an opposite effect of pressure adaptation-a substantial increase in the absolute value of Δ V PP ∘ in deep-living species compared to shallow-water counterparts. With this change, the enzyme activities in abyssal and hadal species do not substantially decrease their activity with pressure increasing up to 1-2 kbar, well beyond full-ocean depth pressures. In contrast, the activity of the enzyme from the tidepool snailfish, L. florae, decreases nearly linearly from 1 to 2500 bar. The increased tolerance of LDH activity to pressure comes at the expense of decreased catalytic efficiency, which is compensated with increased enzyme contents in high-pressure-adapted species. The newly discovered strategy is presumably used when the enzyme mechanism involves the formation of potentially unstable excited transient states associated with substantial changes in enzyme-solvent interactions.

High pressures increase α-chymotrypsin enzyme activity under perchlorate stress

Deep subsurface environments can harbour high concentrations of dissolved ions, yet we know little about how this shapes the conditions for life. We know even less about how the combined effects of high pressure influence the way in which ions constrain the possibilities for life. One such ion is perchlorate, which is found in extreme environments on Earth and pervasively on Mars. We investigated the interactions of high pressure and high perchlorate concentrations on enzymatic activity. We demonstrate that high pressures increase α-chymotrypsin enzyme activity even in the presence of high perchlorate concentrations. Perchlorate salts were shown to shift the folded α-chymotrypsin phase space to lower temperatures and pressures. The results presented here may suggest that high pressures increase the habitability of environments under perchlorate stress. Therefore, deep subsurface environments that combine these stressors, potentially including the subsurface of Mars, may be more habitable than previously thought.

Gault et al. show that high pressures increase α-chymotrypsin enzyme activity in the presence of high perchlorate concentrations. These perchlorate salts shift the folded enzyme phase space to lower temperatures and pressure and may move the optimum enzyme activity towards lower temperatures in addition to higher pressures, which has implications for Martian habitability.

Effect of microwave-assisted processing on polyphenol oxidase and peroxidase inactivation kinetics of açai-berry (Euterpe oleracea) pulp

Microwave heating has been considered a promising technology for continuous flow thermal processing of fluid foods due to better retention of quality. Considering the importance of açai-berry pulp and its perishability, the inactivation kinetics of peroxidase (POD) and polyphenol oxidase (PPO) were investigated under conventional and microwave heating. First-order two-component model was well fitted to the data, indicating the presence of at least two fractions with different resistances. POD was more thermally resistant (90% inactivation for 40 s at 89 °C) and could be considered as a processing target. Inactivation curves dependency on heating technology suggests specific effects of microwaves on the protein structure. Additionally, the dielectric properties of açai-berry pulp were evaluated at 915 and 2,450 MHz for temperatures up to 120 °C. Power penetration depth dropped with temperature at 915 MHz (from 29 to 11 mm), but was less affected at 2,450 MHz (between 8 and 11 mm).

Effect of sonication, microwaves and high-pressure processing on ACE-inhibitory activity and antioxidant potential of Cheddar cheese during ripening

Dairy processing provides acceptable safety and shelf-life to final products, and improves their bioactivity. The present study evaluated the potential of different milk processing techniques to improve the antioxidant and angiotensin-I converting enzyme (ACE)-inhibitory activity of Cheddar cheese, during ripening. Cheese was made from milk subjected to different pre-treatments (C = untreated control, US-1 = ultrasonication, specific energy = 23 J/g, 20 kHz frequency; US-2 = Ultrasonication specific energy = 41 J/g, 20 kHz; HPP = high-pressure processing, 400 MPa for 15 min, at temperature < 40 °C; MW = microwave, temperature<40 °C, specific energy = 86.5 J/g) and analysed after ripening for 0, 3, 6 and 9 months. The results showed that the rate of proteolysis during both cheese making and subsequent ripening was significantly affected by the pre-treatment. Antioxidant activity and ACE-inhibitory potential of cheeses made from pre-treated milk significantly increased (p < 0.05) in the following order: US-2 > HPP > US-1 > MW > C. These findings demonstrate the possibility of using ultrasound, microwaves or high-pressure processing as pre-treatments to improve the nutritional attributes of cheese.

Synthetic reconstruction of extreme high hydrostatic pressure resistance in Escherichia coli

Although high hydrostatic pressure (HHP) is an interesting parameter to be applied in bioprocessing, its potential is currently limited by the lack of bacterial chassis capable of surviving and maintaining homeostasis under pressure. While several efforts have been made to genetically engineer microorganisms able to grow at sublethal pressures, there is little information for designing backgrounds that survive more extreme pressures. In this investigation, we analyzed the genome of an extreme HHP-resistant mutant of E. coli MG1655 (designated as DVL1), from which we identified four mutations (in the cra, cyaA, aceA and rpoD loci) causally linked to increased HHP resistance. Analysing the functional effect of these mutations we found that the coupled effect of downregulation of cAMP/CRP, Cra and the glyoxylate shunt activity, together with the upregulation of RpoH and RpoS activity, could mechanistically explain the increased HHP resistance of the mutant. Using combinations of three mutations, we could synthetically engineer E. coli strains able to comfortably survive pressures of 600-800 MPa, which could serve as genetic backgrounds for HHP-based biotechnological applications.

Enhancement of neuroprotection, antioxidant capacity, and water-solubility of crocins by transglucosylation using dextransucrase under high hydrostatic pressure

Crocin, one of the major carotenoid pigments of Crocus sativus (saffron), is responsible for antioxidant activity, neuroprotection, and the inhibition of tumor cell proliferation. In order to improve the functionality of crocin, α-glucosyl-(1→6)-trans-crocins (C-Gs) were synthesized using sucrose and dextransucrase from Leuconostoc mesenteroides. High hydrostatic pressure (HHP) technique was applied to the synthesis process of C-Gs in order to improve its transglucosylation yield. A 100 MPa HHP condition enhanced the production yield of C-Gs by 1.95 times compared to that of 0.1 MPa atmospheric pressure. Novel C-Gs were purified by HPLC, and their chemical structures were determined using NMR analysis. Novel C-Gs increased water solubility 4.6-5.7 times and antioxidant activity 1.5-2.6 times, respectively, compared to crocin, and their neuroprotections (cell viability 92.5-100.4 %) on HT22 mouse hippocampal neuronal cells were significantly higher than that of crocin (cell viability 84.6 %). This advanced neuroprotection of novel C-Gs could be highly associated with their enhanced antioxidant activity. Thus, the enhanced water solubility and functionality of novel C-Gs can induce better clinical efficacy of neuroprotection than trans-crocin.

Production of protein hydrolysate from Protaetia brevitarsis seulensis (Kolbe) larvae by enzyme treatment under high pressure

To improve the industrial use of health-functional materials based on edible insects, the objective of this study was to establish optimal conditions for improving the quality of Protaetia brevitarsis seulensis larval (PBSL) hydrolysates. PBSL was extracted using four methodologies: atmospheric pressure 50 °C-water extraction, atmospheric pressure 95 °C-water extraction, atmospheric pressure 50 °C-water enzymatic hydrolysis, and enzyme treatment under high pressure (HPE). The quality characteristics of soluble solid content, extraction yield, total protein content, protein yield, protein content with low molecular weight (LMW) (< 1kD), and the amino acid composition of hydrolysates were compared based on the different methods. All of the quality characteristics were found to be higher for HPE extracts than for the other extracts. Under optimized HPE conditions, extraction yield, protein yield, protein content with LMW, amino acid content and the content of essential amino acids increased by 3.4, 4.4 1.4 1.5, and 1.3 times respectively, compared to the other methods.

Impacts of high pressure assisted freezing on the denaturation of polyphenol oxidase

The mechanism of enzyme protein denaturation induced by high pressure freezing is complicated and unclear as this process involves Pressure-Factors (pressure and time) and Freezing-Factors (temperature, phase transition, recrystallization, and ice crystal types). In this study, the thermodynamics and conformation changes of mushroom polyphenol oxidase (PPO) under high pressure freezing treatments (HPF, ^{100,150,200,300,400,500MPa}P_-20°C/30min) and high pressure processes (HPP) followed with normal pressure immersion freezing (HPP-IF, ^100-500MPaP_25°C/30min - ^0.1MPaP_-20°C/30min) are investigated as compared with that processed under high pressure processes (HPP, ^100-500MPaP_25°C/30min) and normal pressure immersion freezing process (IF, ^0.1MPaP_-20°C/30min). The results suggested that the treated PPO with the same enzyme activity may have various thermodynamic characteristics and conformations; Pressure-Factors play the main roles in the denaturation of the PPO during the HPF treatment, and Freezing-Factors can weak the effect of Pressure-Factors on PPO denaturation; The treated PPO may be transferred into a partially fold intermediate state.

In situ and real-time insight into Rhizopus chinensis lipase under high pressure and temperature: Conformational traits and biobehavioural analysis

An in situ and real-time investigation was performed using an optical cell system and in-silico analysis to reveal the impacts of pressure and temperature on the conformational state and behaviours of Rhizopus chinensis lipase (RCL). The fluorescence intensity (FI) of RCL increased remarkably under high pressure, and part of this increase was recovered after depressurization. This result displayed the partially reversible conformational change of RCL, which may be associated with the local change of Trp224 near the catalytic centre. High temperature caused a significant loss of secondary structure, whereas the α-helical segments including the lid were preserved by high pressure even at temperatures over 60 °C. The parameters of enzymatic reaction monitored by UV showed that the hydrolysis rate was remarkably enhanced by the pressure of 200 MPa. In the pressure range of 0.1-200 MPa, the active volume measured by the in situ system decreased from -2.85 to -6.73 mL/mol with the temperature increasing from 20 °C to 40 °C. The high catalytic capacity of the lipase under high pressure and high temperature was primarily attributed to pressure protection on RCL.

Subsurface Stappia: Success Through Defence, Specialisation and Putative Pressure-Dependent Carbon Fixation

Diverse microbial communities living in subsurface coal seams are responsible for important geochemical processes including the movement of carbon between the geosphere, biosphere and atmosphere. Microbial conversion of the organic matter in coal to methane involves a complex assemblage of bacteria and archaea working in syntrophic relationships. Despite the importance and value of this microbial process, very few of the microbial taxa have defined metabolic or ecological roles in these environments. Additionally, the genomic features mediating life in this chemically reduced, energy poor, deep subsurface environment are not well characterised. Here we describe the isolation and genomic and catabolic characterisation of three alphaproteobacterial Stappia indica species from three coal basins across Australia. S. indica genomes from coal seams were compared with those from closely related S. indica isolated from diverse surface waters, revealing a coal seam-specific suite of genes associated with life in the subsurface. These genes are linked to processes including viral defence, secondary metabolite production, polyamine metabolism, polypeptide uptake membrane transporters and putative energy neutral pressure-dependent CO₂ fixation. This indicates that subsurface Stappia have diverse metabolisms for biomass recycling and pressure-dependent CO₂ fixation and require a suite of defensive and competitive strategies relative to their surface-dwelling relatives.

A strategy for promoting γ-glutamyltransferase activity and enzymatic synthesis of S-allyl-(L)-cysteine in aged garlic via high hydrostatic pressure pretreatments

S-allyl-(L)-cysteine (SAC) is a bioactive compound within garlic. Its level is low since SAC formation is impeded by the cellular structure of garlic. This study investigates the effect of high hydrostatic pressure (HHP) pretreatment on SAC formation in garlic aged at 40 °C for 10 days. Results showed that HHP could enhance γ-glutamyltransferase (γ-GTP) activity, damage the cellular structure of garlic and increase SAC content in aged garlic by about 7-10 times, depending on the processing parameters. HHP processing at 300 MPa for 15 min provided the optimal conditions for enhancing γ-GTP activity (45%) and promoting SAC formation (from 0.51 ± 0.01 to 5.60 ± 0.22 mg/g dry weight). It was also found that HHP could induce the greening and browning of aged garlic. As such, we consider that HHP technology is a promising technique to produce aged black garlic products with higher amounts of bioactive compounds.

Characterization of membrane-bound polyphenol oxidase from Granny Smith apple (Malus × domestica Borkh.)

Membrane-bound polyphenol oxidase (mPPO) from the Granny Smith apple was purified and characterized. The enzyme was purified by a factor of 20.53 with a recovery of 1.8%. The molecular weight of purified mPPO was determined to be 65 kDa by electrophoresis and nano-electrospray ionization mass spectrometry. mPPO exhibited its highest activity at a temperature of 35 °C and a pH of 7.0 and can be regarded as a diphenol oxidase. A low concentration of SDS (≤0.5 mM) enhanced the enzymatic activity, whereas mPPO was activated at high concentration EDTA (≥2 mM). The thermal transition temperature of mPPO was 76.98 °C. The circular dichroism spectrum showed that mPPO contains high α-helix content, the fluorescence spectroscopy indicated that the tryptophan residues of mPPO are partially buried. The particle size of mPPO was 5-10 nm with a complete structure. The structural characterization of mPPO provided better insights into the regions responsible for its activity.

Modulation of enzymatic activity by aqueous two-phase systems and pressure – rivalry between kinetic constants

Both, pressure and aqueous two-phase systems are able to modulate the kinetic parameters of enzymatic reactions.

The multifaceted effects of DMSO and high hydrostatic pressure on the kinetic constants of hydrolysis reactions catalyzed by α-chymotrypsin

The cosolvent DMSO and high pressure have antagonistic effects on the kinetic constants of α-chymotrypsin-catalyzed hydrolysis reactions.

Stability and Stabilization of Enzyme Biosensors: The Key to Successful Application and Commercialization

Fifty-five years have passed and more than 100,000 articles have been published since the first report of an electrochemical enzyme biosensor. However, very few biosensors have reached practical application and commercialization. The bulk of the research effort has been on increasing sensitivity and selectivity. In contrast, the number of publications dealing with stability or stabilization of enzyme biosensors is very small. Here, we critically review enzyme stabilization strategies as well as the progress that has been done in the past 20 years with respect to enzyme biosensor stabilization. Glucose oxidase, lactate oxidase, alcohol oxidase, and xanthine oxidase are the focus of this review because of their potential applications in food. The inconsistency in reporting biosensor stability was identified as a critical hurdle to research progress in this area. Fundamental questions that remain unanswered are outlined.

Density variations of TMAO solutions in the kilobar range: Experiments, PC-SAFT predictions, and molecular dynamics simulations

We present measurements, molecular dynamics (MD) simulations, and predictions using Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) of the density of aqueous solutions in a pressure range from 1 bar to 5000 bar, a pressure regime that is highly relevant for both biochemical applications and the fundamental understanding of solvation. The accurate determination of density data of pressurized solutions remains challenging. We determined relative density changes from the variations in X-ray absorption through the sample and developed a new water parameter set for PC-SAFT modeling that is appropriate for high pressure conditions in the kilobar regime. As a showcase, we studied trimethylamine N-oxide (TMAO) solutions and demonstrated that their compressibility decreases with the TMAO content. This result is linked to the stabilizing effect of TMAO on the local H-bond network of water. Experiments and calculations, which represent two independent methods, are in very good agreement and are in accordance with results of force field molecular dynamics simulations of the same systems.

Hyperbaric Storage at Room Temperature for Fruit Juice Preservation

Hyperbaric storage is an innovative preservation method that consists of storing food under pressure, either at room or at low temperature, for time periods of days, weeks, or months. Recent scientific literature shows that hyperbaric storage at room temperature (HS-RT) could be an efficient method for fruit juice preservation. Depending on the level applied, pressure can inhibit and even inactivate the endogenous microflora of the fresh juice, while properly preserving other organoleptic and quality indicators. Even though the method has not yet been implemented in the food industry, its industrial viability has been evaluated from different points of view (product quality, consumer acceptation, vessel design, economic, or environmental, among others). The results reveal that HS-RT is effective in extending the shelf-life of both acidic and low-acidic fruit juices. Moreover, the energetic costs and the carbon footprint of HS-RT are considerably lower than those of refrigeration, therefore, HS-RT could be a reliable and environmentally friendly alternative to conventional cold storage. However, before industrial implementation, much more research is needed to clarify the effects of the storage conditions on the agents that cause fruit juice deterioration.

Bridging the Knowledge Gap for the Impact of Non-Thermal Processing on Proteins and Amino Acids

Proteins represent one of the major food components that contribute to a wide range of biophysical functions and dictate the nutritional, sensorial, and shelf-life of food products. Different non-thermal processing technologies (e.g., irradiation, ultrasound, cold plasma, pulsed electric field, and high-pressure treatments) can affect the structure of proteins, and thus their solubility as well as their functional properties. The exposure of hydrophobic groups, unfolding followed by aggregation at high non-thermal treatment intensities, and the formation of new bonds have been reported to promote the modification of structural and functional properties of proteins. Several studies reported the reduction of allergenicity of some proteins after the application of non-thermal treatments. The composition and concentration of free amino acids could be changed after non-thermal processing, depending on the processing time and intensity. The present review discusses the effects of different non-thermal treatments on protein properties in detail, and highlights the opportunities and disadvantages of these technologies in relation to protein functionality.

High-pressure study of magnetic nanoparticles with a polyelectrolyte brush as carrier particles for enzymes

The recovery of enzymes from a reaction medium can be achieved in a convenient way by using magnetic nanoparticles (MNP) as carriers. Here, we present MNP with a polyelectrolyte brush composed of poly(ethylene imine) (PEI) to provide a benign environment for the immobilized enzyme molecules. Yeast alcohol dehydrogenase (ADH) has been tested for enzymatic activity when it is free in solution or adsorbed on the PEI brush-MNP. Furthermore, the effect of pressure on the enzymatic activity has been studied to reveal activation volumes, which are a sensitive probe of the transition state geometry. The results of this study indicate that the secondary structure of ADH is pressure-stable up to 9 kbar. The enzymatic activity of ADH can be analyzed using Michaelis-Menten kinetics free in solution and adsorbed on the PEI brush-MNP. Remarkably, no significant changes of the Michaelis constant and the activation volume are observed upon adsorption. Thus, it can be assumed that the turnover number of ADH is also the same in the free and adsorbed state. However, the maximum enzymatic rate is reduced when ADH is adsorbed, which must be explained by a lower effective enzyme concentration due to steric hindrance of the enzyme inside the PEI brush of the MNP. In this way, the pressure experiments carried out in this study enable a distinction between steric and kinetic effects on the enzymatic rate of adsorbed ADH.

Thermodynamic properties of aqueous osmolyte solutions at high-pressure conditions

Living organisms can be encountered in nature under extreme conditions. At the seabed, pressure may reach 1000 bar. Yet microorganisms can be found that still function under these conditions. On the one hand, it is known that high pressure even has a positive effect on piezophile enzymes increasing their activity. On the other hand, such microorganisms might contain up to very high concentrations of osmolytes that counteract osmotic stress. To better understand high-pressure influences on biochemical systems, fundamental knowledge about pressure effects on thermodynamic properties of such osmolytes is important. However, literature data is scarce and experiments at high-pressure conditions are challenging. Hence, new high-pressure density data of aqueous osmolyte solutions were measured in this work at temperatures between 298.15 K and 318.15 K and at osmolyte concentrations up to 3 mol/kg water. Further, the thermodynamic model PC-SAFT has been applied recently to successfully model vapor pressures of water and density of water up to 10 kbar [M. Knierbein et al., Density variations of TMAO solutions in the kilobar range: experiments, PC-SAFT predictions, and molecular dynamics simulations, Biophysical chemistry, (2019)]. This allowed accurately predicting effects of temperature and osmolyte concentration on thermodynamic properties (especially mixture densities) up to very high pressures. Common osmolytes (trimethylamine-N-oxide, urea, ectoine, glycerol, glycine) as well as the dipeptides acetyl-N-methylglycine amide, acetyl-N-methylalanine amide, and acetyl-N-methylleucine amide were under investigation.

Osmolytes modify protein dynamics and function of tetrameric lactate dehydrogenase upon pressurization

We present a study of the combined effects of natural cosolvents (TMAO, glycine, urea) and pressure on the activity of the tetrameric enzyme lactate dehydrogenase (LDH). To this end, high-pressure stopped-flow methodology in concert with fast UV/Vis spectroscopic detection of product formation was applied. To reveal possible pressure effects on the stability and dynamics of the enzyme, FTIR spectroscopic and neutron scattering measurements were carried out. In neat buffer solution, the catalytic turnover number of the enzyme, k_cat, increases up to 1000 bar, the pressure range where dissociation of the tetrameric species to dimers sets in. Accordingly, we obtain a negative activation volume, ΔV^# = -45.3 mL mol^-1. Further, the enzyme substrate complex has a larger volume compared to the enzyme and substrate in the unbound state. The neutron scattering data show that changes in the fast internal dynamics of the enzyme are not responsible for the increase of k_cat upon compression. Whereas the magnitude of k_cat is similar in the presence of the osmolytes, the pressure of deactivation is modulated by the addition of cosolvents. TMAO and glycine increase the pressure of deactivation, and in accordance with the observed stabilizing effect both cosolvents exhibit against denaturation and/or dissociation of proteins. While urea does not markedly affect the magnitude of the Michaelis constant, K_M, both 1 M TMAO and 1 M glycine exhibit smaller K_M values of about 0.07 mM and 0.05 mM below about 1 kbar. Such positive effect on the substrate affinity could be rationalized by the effect the two cosolutes impose on the thermodynamic activities of the reactants, which reflect changes in water-mediated intermolecular interactions. Our data show that the intracellular milieu, i.e., the solution conditions that have evolved, may be sufficient to maintain enzymatic activity under extreme environmental conditions, including the whole pressure range encountered on Earth.

Interrogating the Structural Dynamics and Energetics of Biomolecular Systems with Pressure Modulation

High hydrostatic pressure affects the structure, dynamics, and stability of biomolecular systems and is a key parameter in the context of the exploration of the origin and the physical limits of life. This review lays out the conceptual framework for exploring the conformational fluctuations, dynamical properties, and activity of biomolecular systems using pressure perturbation. Complementary pressure-jump relaxation studies are useful tools to study the kinetics and mechanisms of biomolecular phase transitions and structural transformations, such as membrane fusion or protein and nucleic acid folding. Finally, the advantages of using pressure to explore biomolecular assemblies and modulate enzymatic reactions are discussed.

Effects of ultra-high pressure on effective synthesis of fructooligosaccharides and fructotransferase activity using Pectinex Ultra SP-L and inulinase from Aspergillus niger

In this study, various levels of ultra-high pressure (UHP) were combined with the enzymatic synthesis of the fructooligosaccharide (FOS) using Pectinex Ultra SP-L and inulinase. The combination enhanced the FOS yields up to 2.5- and 1.5-fold, respectively, compared to atmospheric condition (0.1 MPa). However, the enzymatic reaction was dependent on the levels of pressure, the reaction times, and the initial sucrose concentrations. The combined UHP and inulinase showed that the maximum FOS yield (71.81%) was obtained under UHP at 200 MPa for 20 min with 300 g/L of initial sucrose as a substrate, while the FOS yield (57.13%) using Pectinex Ultra SP-L was obtained under UHP at 300 MPa for 15 min with 600 g/L of initial sucrose as a substrate. The FOS composition produced by Pectinex Ultra SP-L under the UHP was 1-kestose (GF₂), nystose (GF₃), and 1F-fructofuranosylnystose (GF₄), whereas the FOS produced by inulinase composed of only GF₂ and GF₃. The combined UHP is a useful tool in the industrial application for FOS production. Highlights UHP activated the activity of Pectinex Ultra SP-L yet inactivated inulinase Pressure level, time, and sucrose concentration significantly affect FOS yields under UHP UHP enhanced FOS production with time-saving benefits within 15-20 min.