Heat-denatured Proteins Research Articles

Formulations and evaluations of structural and physico-chemical properties of soy yogurts: Effect of incorporating soy protein isolate/chitosan complexed microgels

Novel complexed microgels with enhanced pH and ion stability were constructed using heat-denatured soy protein isolate (SPI) and Chitosan (CS). Their characteristics and their effects on the textural, rheological, and tribological properties of soy yogurt were investigated. The complexed microgels showed larger particle sizes, lower surface hydrophobicity, and higher turbidity than pure SPI microgels. Incorporating the SPI-CS complexed microgels into the yogurts increased their protein content from 3.94% to 5.07% and reduced their fat content from 2.17% to 1.99%. Additionally, incorporating the microgels enhanced the texture of the yogurts, including increased firmness, elasticity, and viscosity, alongside improved water holding capacity (WHC). The incorporation of 0.8% SPI-CS microgels led to the optimum physicochemical characteristics. Rheological analyses demonstrated that incorporating SPI-CS microgels led to an increase in apparent viscosity and shear modulus. Furthermore, the presence of the SPI-CS microgels significantly improved the lubrication properties. Microstructural analysis showed subtle differences in the gel structure of the yogurts after microgel addition. The three-dimensional network structure within the microgel-fortified yogurts was more compact than that in the control. Thus, SPI-CS microgels potentially improve the nutritional profile and quality attributes of plant-based yogurt products.

Methylmercury in northern pike (Esox lucius) liver and hepatic mitochondria is linked to lipid peroxidation

Methylmercury (MeHg) readily bioaccumulates and biomagnifies in aquatic food webs leading to elevated concentrations in fish and may thus induce toxicity. Oxidative stress is a suggested effect of MeHg bioaccumulation in fish. However, studies on how MeHg triggers oxidative stress in wild fish are scarce. The purpose of this study was to link the subcellular distribution of MeHg in the liver of northern pike from the St. Maurice River (Québec, Canada), affected by two run-of-river (RoR) dams, artificial wetlands, forest fires, and logging activity, to lipid peroxidation as an indicator of oxidative stress. We also evaluated the protective effects of the glutathione (GSH) system and selenium (Se), as they are known to alleviate MeHg toxicity. A customized subcellular partitioning protocol was used to separate the liver into metal-sensitive (mitochondria, microsome/lysosome and HDP – heat-denatured proteins) and metal-detoxified fractions (metal-rich granules and HSP – heat-stable proteins). We examined the relation among THg, MeHg, and Se concentration in livers and subcellular fractions, and the hepatic ratio of total GSH (GSHt) to oxidized glutathione (GSSG) on lipid peroxidation levels, using the concentrations of malondialdehyde (MDA), a product of lipid peroxidation. Results showed that hepatic MDA concentration was positively correlated with the combined MeHg and Se concentrations in northern pike liver (r2 = 0.88, p < 0.001) and that MDA concentrations were best predicted by MeHg associated with the mitochondria (r2 = 0.71, p < 0.001). This highlights the need for additional research on the MeHg influence on fish health and the interactions between Hg and Se in northern pike.

Impact of κ-Carrageenan on the Cold-Set Pea Protein Isolate Emulsion-Filled Gels: Mechanical Property, Microstructure, and In Vitro Digestive Behavior

More understanding of the relationship among the microstructure, mechanical property, and digestive behavior is essential for the application of emulsion gels in the food industry. In this study, heat-denatured pea protein isolate particles and κ-carrageenan were used to fabricate cold-set emulsion gels induced by CaCl2, and the effect of κ-carrageenan concentration on the gel formation mechanism, microstructure, texture, and digestive properties was investigated. Microstructure analysis obtained by confocal microscopy and scanning electron microscopy revealed that pea protein/κ-carrageenan coupled gel networks formed at the polysaccharide concentration ranged from 0.25% to 0.75%, while the higher κ-carrageenan concentration resulted in the formation of continuous and homogenous κ-carrageenan gel networks comprised of protein enriched microdomains. The hydrophobic interactions and hydrogen bonds played an important role in maintaining the gel structure. The water holding capacity and gel hardness of pea protein emulsion gels increased by 37% and 75 fold, respectively, through increasing κ-carrageenan concentration up to 1.5%. Moreover, in vitro digestion experiments based on the INFOGEST guidelines suggested that the presence of 0.25% κ-carrageenan could promote the digestion of lipids, but the increased κ-carrageenan concentration could delay the lipid and protein hydrolysis under gastrointestinal conditions. These results may provide theoretical guidance for the development of innovative pea protein isolate-based emulsion gel formulations with diverse textures and digestive properties.

Inclusion of deuterated glycopeptides provides increased sequence coverage in hydrogen/deuterium exchange mass spectrometry analysis of SARS-CoV-2 spike glycoprotein.

Hydrogen/deuterium exchange mass spectrometry (HDX-MS) can provide precise analysis of a protein's conformational dynamics across varied states, such as heat-denatured versus native protein structures, localizing regions that are specifically affected by such conditional changes. Maximizing protein sequence coverage provides high confidence that regions of interest were located by HDX-MS, but one challenge for complete sequence coverage is N-glycosylation sites. The deuteration of peptides post-translationally modified by asparagine-bound glycans (glycopeptides) has not always been identified in previous reports of HDX-MS analyses, causing significant sequence coverage gaps in heavily glycosylated proteins and uncertainty in structural dynamics in many regions throughout a glycoprotein. We detected deuterated glycopeptides with a Tribrid Orbitrap Eclipse mass spectrometer performing data-dependent acquisition. An MS scan was used to identify precursor ions; if high-energy collision-induced dissociation MS/MS of the precursor indicated oxonium ions diagnostic for complex glycans, then electron transfer low-energy collision-induced dissociation MS/MS scans of the precursor identified the modified asparagine residue and the glycan's mass. As in traditional HDX-MS, the identified glycopeptides were then analyzed at the MS level in samples labeled with D2 O. We report HDX-MS analysis of the SARS-CoV-2 spike protein ectodomain in its trimeric prefusion form, which has 22 predicted N-glycosylation sites per monomer, with and without heat treatment. We identified glycopeptides and calculated their average isotopic mass shifts from deuteration. Inclusion of the deuterated glycopeptides increased sequence coverage of spike ectodomain from 76% to 84%, demonstrated that glycopeptides had been deuterated, and improved confidence in results localizing structural rearrangements. Inclusion of deuterated glycopeptides improves the analysis of the conformational dynamics of glycoproteins such as viral surface antigens and cellular receptors.

Exploring the subcellular distribution of mercury in green alga Chlamydomonas reinhardtii and diatom Cyclotella meneghiniana: A comparative study

Mercury (Hg) is a priority pollutant of global concern because of its toxicity, its ability to bioaccumulate throughout the food web and reach significant concentrations in top predators. Phytoplankton bioconcentrate large amounts of Hg and play a key role in the entry of Hg into the aquatic food web. However, the subcellular distribution of Hg in freshwater phytoplankton, known to affect it toxicity and trophic transfer is understudied. The present study aimed at investigating the accumulation of inorganic Hg (iHg) and its subcellular distribution in freshwater phytoplankton species. To this end green alga Chlamydomonas reinhardtii and diatom Cyclotella meneghiniana were exposed to 10 and 100 nM of iHg for 2 h. The concentrations of Hg in the adsorbed, intracellular and subcellular (granules, debris, organelles, heat-stable peptides (HSP) and heat-denaturable proteins (HDP)) fractions were determined. The results showed that C. meneghiniana accumulated more Hg compared to C. reinhardtii at both iHg exposure concentrations (10 nM: 4.41 ± 0.74 vs. 1.10 ± 0.25 amol cell−1; 100 nM: 79.35 ± 10.78 vs. 38.31 ± 4.15 amol cell−1). The evaluation of the subcellular distribution of Hg, revealed that the majority of Hg was concentrated in the organelles fraction (59.7 % and 74.6 %) in the green algae. In the diatom, Hg was mainly found in the organelles (40.9 % and 33.3%) and in the HSP fractions (26.8 % and 40.1 %). The proportion of Hg in HDP fraction decreased in favor of the organelles fraction in C. reinhardtii when the exposure concentration increased, whereas the proportions in the debris and organelles fractions decreased in favor of HSP fraction in C. meneghiniana. This study provides pioneering information on the subcellular distribution of Hg within in freshwater phytoplankton, a knowledge that is essential to understand the toxicity and trophic transfer of Hg in contaminated aquatic environment.

Investigating the mechanism of antioxidants as egg white powder flavor modifiers.

The uses of egg white powder (EWP) are restricted because of its odor. It is necessary to find a method to improve its flavor. In this paper, three different antioxidants - green tea extract (GTE), sodium ascorbate (SA), and glutathione (GSH) - were selected to modify the flavor. The physicochemical and structural properties of EWP were investigated to study the mechanism of the formation and release of volatile compounds. Antioxidants can modify the overall flavor of EWP significantly, inhibiting the generation or release of nonanal, 3-methylbutanal, heptanal, decanal, geranyl acetone, and 2-pemtylfuran. A SA-EWP combination showed the lowest concentration of 'off' flavor compounds; GTE-EWP and GSH-EWP could reduce several 'off' flavor compounds but increased the formation of geranyl acetone and furans. The changes in the carbonyl content and the amino acid composition confirmed the inhibition of antioxidants with the oxidative degradation of proteins or characteristic amino acids. The results of fluorescence spectroscopy and Fourier transform infrared (FTIR) spectroscopy provided structural information regarding EWP, which showed the release of volatile compounds decreased due to structural changes. For example, the surface hydrophobicity increased and the protein aggregation state changed. Antioxidants reduce the 'off' flavor of EWP in two ways: they inhibit protein oxidation and Maillard reactions (they inhibit formation of 3-methylbutanal and 2-pemtylfuran) and they enhance the binding ability of heat-denatured proteins (reducing the release of nonanal, decanal, and similar compounds). © 2023 Society of Chemical Industry.

Enhanced Inhibition of Amyloid Formation by Heat Shock Protein 90 Immobilized on Nanoparticles.

As the population ages, an epidemic of neurodegenerative diseases with devastating social consequences is looming. To address the pathologies leading to amyloid-related dementia, novel therapeutic strategies must be developed for the treatment or prevention of neural protein-folding disorders. Nanotechnology will be crucial to this scenario, especially in the design of nanoscale systems carrying therapeutic compounds that can navigate the nervous system and identify amyloid to treat it in situ. In this line, we have recently designed a highly simplified and versatile nanorobot consisting of a protein coating based on the heat shock protein 90 (Hsp90) chaperone that not only propels nanoparticles using ATP but also endows them with the extraordinary ability to fold and restore the activity of heat-denatured proteins. Here, we assess the effectiveness of these nanosystems in inhibiting/reducing the aggregation of amyloidogenic proteins. Using Raman spectroscopy, we qualitatively and quantitatively analyze amyloid by identifying and semi-quantifying the Amide I band. Our findings indicate that the coupling of Hsp90 to nanoparticles results in a more potent inhibition of amyloid formation when compared to the soluble protein. We propose that this enhanced performance may be attributed to enhanced release-capture cycles of amyloid precursor oligomers by Hsp90 molecules nearby on the nanosurface. Intelligent biocompatible coatings, like the one described here, that enhance the diffusivity and self-propulsion of nanoparticles while enabling them to carry out critical functions such as environmental scanning, identification, and amyloid prevention, present an exceptional opportunity for the development of advanced nanodevices in biomedical applications. This approach, which combined active biomolecules with synthetic materials, is poised to reveal remarkable prospects in the field of nanomedicine and biotechnology.

Transcriptional regulation of Sis1 promotes fitness but not feedback in the heat shock response.

The heat shock response (HSR) controls expression of molecular chaperones to maintain protein homeostasis. Previously, we proposed a feedback loop model of the HSR in which heat-denatured proteins sequester the chaperone Hsp70 to activate the HSR, and subsequent induction of Hsp70 deactivates the HSR (Krakowiak et al., 2018; Zheng et al., 2016). However, recent work has implicated newly synthesized proteins (NSPs) - rather than unfolded mature proteins - and the Hsp70 co-chaperone Sis1 in HSR regulation, yet their contributions to HSR dynamics have not been determined. Here, we generate a new mathematical model that incorporates NSPs and Sis1 into the HSR activation mechanism, and we perform genetic decoupling and pulse-labeling experiments to demonstrate that Sis1 induction is dispensable for HSR deactivation. Rather than providing negative feedback to the HSR, transcriptional regulation of Sis1 by Hsf1 promotes fitness by coordinating stress granules and carbon metabolism. These results support an overall model in which NSPs signal the HSR by sequestering Sis1 and Hsp70, while induction of Hsp70 - but not Sis1 - attenuates the response.

Effects of Culinary Procedures on Concentrations and Bioaccessibility of Cu, Zn, and As in Different Food Ingredients.

Although cooked diets are the primary sources for humans to absorb trace elements, there is limited data available on the concentrations and bioaccessibility of trace elements in cooked food ingredients. This work aims to evaluate the effects of culinary procedures on the concentrations and bioaccessibility of trace elements in common food ingredients. Twelve food species from the local market were treated with four culinary procedures (boiling, steaming, baking, and frying), then the bioaccessibility of copper (Cu), zinc (Zn), and arsenic (As) were evaluated using the in vitro digestion method. The subcellular distribution of these elements was also determined using the sequential fractionation method. The results show that culinary procedures decreased the retention rate of As during cooking (100% for raw and 65-89% for cooked ingredients) and the bioaccessibility of Cu and Zn during digestion (nearly 75% for raw and 49-65% for cooked ingredients), resulting in a reduction of the total bioaccessible fraction (TBF) of Cu, Zn, and As in food ingredients. The TBF of Cu, Zn, and As in all tested food ingredients followed the order: raw (76-80%) > steaming and baking (50-62%) > boiling and frying (41-50%). The effects of culinary procedures were associated with the subcellular distribution of trace elements. As was dominantly distributed in heat-stable proteins (51-71%), which were more likely to be lost during cooking. In comparison, Cu and Zn were mainly bound to the insoluble fraction and heat-denatured proteins (60-89% and 61-94% for Cu and Zn, respectively), which become less digestible in cooked ingredients. In conclusion, these results suggest that culinary procedures reduce the absorption of Cu, Zn, and As in various food ingredients, which should be considered in the coming studies related to nutrition and risk assessment of trace elements.

Structural characteristics and acid-induced emulsion gel properties of heated soy protein isolate–soy oligosaccharide glycation conjugates

Glycation conjugates were prepared by heating the mixed dispersions of heat-denatured soy protein isolate (HSPI) and soy oligosaccharide (SOS) at 90 °C for 30, 60, 90 and 120 min. The structural characteristics and acid-induced emulsion gel properties of HSPI–SOS conjugates were investigated. The results of degree of graft, pH, intermediates and browning intensity showed that the degree of glycosylation gradually increased with the extension of reaction time, but it decreased at 120 min of reaction. The changes of the absorption peaks in infrared spectra confirmed that HSPI was covalently linked with SOS to form HSPI–SOS conjugates through Maillard reaction. The glycosylation of HSPI with SOS resulted in the transformation form α-type to β-type secondary structure, the reduction in free sulfhydryl groups, and the enhancement of surface hydrophobicity. These structural changes of HSPI–SOS conjugates could influence their glucono-δ-lactone-induced emulsion gel properties. Although the glycosylation decreased the storage modulus of HSPI emulsion gels, the 60 min glycated conjugates accelerated the gelation rate of the emulsions. The conjugate emulsion gels had higher gel hardness and water holding capacity, which exhibited more compact microstructure with smaller and more uniform emulsified oil droplets. Moreover, the glycosylation of HSPI with SOS for 60 min improved the thermal stability of conjugate emulsion gels. Therefore, the structure of HSPI–SOS conjugates can be modified by controlling the degree of glycosylation to improve the physicochemical properties and stability of the emulsion gels.

Formation, physicochemical properties, and comparison of heat- and enzyme-induced whey protein-gelatin composite hydrogels

Hydrogels are widely used in the food industry due to their desirable physicochemical and functional attributes. The combination of two or more biopolymers can be used to formulate hydrogels with novel or improved attributes. In this study, whey protein isolate (WPI) and gelatin were used to prepare composite hydrogels using either heat- or enzymatic-crosslinking methods. For heat-induced gelation, gelatin-WPI mixtures were heated above the thermal denaturation temperature of the whey proteins to unfold and crosslink them. For enzyme-induced gelation, transglutaminase was added to crosslink both the gelatin and heat-denatured whey proteins in the gelatin-WPI mixtures. The effects of pH and crosslinking methods on the formation and properties of the hydrogels were investigated. The initial pH of the WPI solution influenced the thermal aggregation of the proteins by affecting the electrostatic interactions between them, thereby influencing the macroscopic properties of the hydrogels formed. For instance, heat-induced hydrogels with a higher elastic modulus were formed at pH 6 (1767 Pa) than at pH 7 (866 Pa) or pH 8 (735 Pa). The enzyme-induced hydrogels set more rapidly and had a considerably higher elastic modulus at pH 7 (2566 Pa) and pH 8 (1566 Pa) than the heat-induced ones. The enzyme-induced hydrogels also exhibited greater hardness and swelling, but the heat-induced ones exhibited better freeze-thaw stability. By changing the pH and crosslinking methods, the structure and texture of the composite hydrogels could be controlled, which may allow these systems to be used for a broad range of commercial applications in food and other industries.

Copper uptake and subcellular distribution in five marine phytoplankton species

Copper (Cu) uptake and trophic transfer in marine plankton at the environmentally relevant levels have rarely been investigated. In this study, we investigated the Cu uptake and subcellular distribution in five phytoplankton (Isochrysis zhanjiangensis, Phaeocystis sp., Isochrysis galbana, Chaetoceros sp. and Phaeodactylum tricornutum) belonging to two taxa Chrysophyta and Bacillariophyta, and the following trophic transfer to rotifer Brachionus plicatilis by using stable isotope tracing method. In 2-hour exposure, Cu uptake rates were 20.8–60.3 amol h-1 cell-1 (amol = 10-18 mol) in the phytoplankton exposure to 4.82 × 10-13 mol L-1 free Cu activity ([Cu2+]). Cu uptake rates were increased with the increase of [Cu2+] in all the phytoplankton species. Generally, Cu uptake rate constants (kus) were lower in Bacillariophyta (Chaetoceros sp. and P. tricornutum) than Chrysophyta (I. zhanjiangensis, Phaeocystis sp. and I. galbana). While in long-term (6 day) exposure, more Cu was accumulated in the Bacillariophyta than in Chrysophyta, suggesting Bacillariophyta might have more Cu capacity than Chrysophyta. Size effects of cells on Cu uptake were not observed among these five phytoplankton. Cu was mainly distributed in the heat-denatured protein plus organelle fraction and head-stable protein fraction in all the five phytoplankton. The Cu assimilation efficiencies (AEs) in rotifer feeding I. zhanjiangensis, Phaeocystis sp., I. galbana, Chaetoceros sp. and P. tricornutum were 63.4%, 57.6%, 60.2%, 77.4% and 14.6%, respectively. These Cu AEs were positively correlated to the Cu distribution in the trophically available metal fraction (TAM) in different phytoplankton. These results herein demonstrated that different marine phytoplankton had different strategies to accumulate Cu that influence Cu transfer to the predators. Therefore, the variation of the phytoplankton community will change the Cu biogeochemistry in marine environment.

Encapsulation of DHA oil with heat-denatured whey protein in Pickering emulsion improves its bioaccessibility

This study compared the bioaccessibility of docosahexaenoic acid (DHA) provided encapsulated or unencapsulated within a food matrix. DHA oil was composed of DHA-enriched triacylglycerols prepared as Pickering emulsion by encapsulation with heat-denatured whey protein isolate particles and then incorporated into homogenized liquid egg to get omelets. The effect of encapsulation was analyzed by using a static in vitro digestion model of the adult, which digestive fluid enzymes have also been characterized by proteomics. First, the size of lipid droplets was shown to be smaller and uniformly dispersed in omelets with encapsulated-DHA oil compared to non-encapsulated-DHA oil. Distribution of droplets was more regular with encapsulated-DHA oil as well. As a consequence, we showed that encapsulating DHA oil promoted the hydrolysis by pancreatic lipase during the intestinal phase. A larger proportion of DHA enriched-triacylglycerols was hydrolyzed after two hours of digestion, leading to a greater release in free DHA. Thus, only 32% of DHA remained esterified in the triacylglycerols with encapsulated-DHA oil, compared to 43% with non-encapsulated-DHA oil. The DHA in free form ultimately represented 52% of the total DHA with encapsulated-DHA oil, compared to 40% with non-encapsulated-DHA oil. Finally, our results showed that as much DHA was released after one hour of intestinal digestion when the DHA oil was encapsulated as after two hours when the DHA oil was not encapsulated. Therefore, DHA bioaccessibility was significantly improved by encapsulation of DHA oil in omelets.

Resveratrol Promotes LRSAM1 E3 Ubiquitin Ligase-Dependent Degradation of Misfolded Proteins Linked with Neurodegeneration.

Cells require regular maintenance of proteostasis. Synthesis of new polypeptides and elimination of damaged or old proteins is an uninterrupted mechanism essential for a healthy cellular environment. Impairment in the removal of misfolded proteins can disturb proteostasis; such toxic aggregation of misfolded proteins can act as a primary risk factor for neurodegenerative diseases and imperfect ageing. The critical challenge is to design effective protein quality control (PQC) based molecular tactics that could potentially eliminate aggregation-prone protein load from the cell. Still, targeting specific components of the PQC pathway for the suppression of proteotoxic insults retains several challenges. Earlier, we had observed that LRSAM1 promotes the degradation of aberrant proteins. Here, we examined the effect of resveratrol, a stilbenoid phytoalexin compound, treatment on LRSAM1 E3 ubiquitin ligase, involved in the spongiform neurodegeneration. In this study, we reported induction of mRNA and protein levels of LRSAM1 in response to resveratrol treatment via RT-PCR, immunoblotting, and immunofluorescence analysis. The LRSAM1-mediated proteasomal-based clearance of misfolded proteins was also investigated via proteasome activity assays, immunoblotting and immunofluorescence analysis. The increased stability of LRSAM1 by resveratrol was demonstrated by cycloheximide chase analysis. Here, we show that resveratrol treatment induces LRSAM1 E3 ubiquitin ligase expression levels. Further, our findings suggest that overexpression of LRSAM1 significantly elevates proteasome activities and improves the degradation of bona fide heat-denatured luciferase protein. Exposure of resveratrol not only slows down the turnover of LRSAM1 but also effectively degrades abnormal proteinaceous inclusions, which eventually promotes cell viability. Our findings suggest that resveratrol facilitates LRSAM1 endogenous establishment, which consequently promotes the proteasome machinery for effective removal of intracellular accumulated misfolded or proteasomal-designated substrates. Altogether, our study proposes a promising molecular approach to specifically trigger PQC signaling for efficacious rejuvenation of defective proteostasis via activation of overburdened proteolytic machinery.

Characteristics, formation mechanism and stability of high internal phase emulsions stabilized by porcine plasma protein (PPP) / carrageenan (CG) hybrid particles

High internal phase emulsions (HIPEs) stabilized by nanoparticles based on biomacromolecules are challenging issues in recent decade. Herein, a newly developed HIPE was investigated by using heat-denatured porcine plasma protein (PPP) nanoparticles at pH 6.5 as emulsifier, and its emulsifying stability could be significantly enhanced by compounding carrageenan (CG). In the miscible system, PPP and CG formed hybrid particles through non-covalent interaction, and the sizes and zeta-potentials of the particles increased significantly along with addition of CG (from 0 to 0.7%, w/v), reached up to about 3.6 μm and −53 mV at 0.5% (w/v), respectively. CG weakened the ability of PPP to lower interfacial tension of oil/water (O/W), but increased the apparent viscosity of the system. The results from CLSM, rheology and stability experiments indicated a significant increasing trend of the HIPEs stability and solid-like characteristics along with addition of CG. Compared with the controls including bovine serum albumin (BSA), BSA-CG and CG alone, PPP-CG hybrid particles had good performance in fabricating and stabilizing the HIPEs. The work revealed the novel function of PPP as emulsifier of HIPEs and so offered the theoretical direction for application of PPP as a mass by-product, as well as an excellent HIPEs system for food, medicine and cosmetics fields.

Production of Plant-Based Seafood: Scallop Analogs Formed by Enzymatic Gelation of Pea Protein-Pectin Mixtures.

This study investigated the possibility of using a phase separation, mixing, and enzymatic gelation approach to construct seafood analogs from plant protein-polysaccharide mixtures with properties mimicking real seafood. Heat-denatured pea protein (10%, w/w) and pectin (0–1%, w/w) were mixed to produce phase separated biopolymer blends. These blends were then subjected to mild shearing (350 rpm) to obtain fiber-like structures, which were then placed in molds and set by gelling the pea proteins using transglutaminase (2%, w/w). The appearance, texture, and cooking properties of the resulting scallop analogs were characterized and compared to those of real scallop. The presence of the pectin promoted the formation of a honeycomb structure in the scallop analogs, and microscopic orientation of the proteins was observed in the plane parallel to the applied shear flow. Lower pectin concentrations (0.5%, w/w) led to stronger gels with better water holding capacity than higher ones (1.0%, w/w). The appearance and texture of the plant-based scallop analogs were like those of real scallop after grilling, indicating the potential of using this soft matter physics approach to create plant-based seafood analogs. One of the main advantages of this method is that it does not require any expensive dedicated equipment, such as an extruder or shear cell technology, which may increase its commercial viability.

Metal-Nanoparticle-Supported Nanozyme-Based Colorimetric Sensor Array for Precise Identification of Proteins and Oral Bacteria.

Convenient, precise, and high-throughput discrimination of multiple bioanalytes is of great significance for an early diagnosis of diseases. Array-based pattern recognition has proven to be a powerful tool to detect diverse analytes, but developing sensing elements featuring favorable surface diversity still remains a challenge. In this work, we presented a simple and facile method to prepare programmable metal-nanoparticle (NP)-supported nanozymes (MNNs) as artificial receptors for the accurate identification of multiple proteins and oral bacteria. The in situ reduction of metal NPs on hierarchical MoS2 on polypyrrole (PPy), which generated differential nonspecific interactions with bioanalytes, was envisaged as the encoder to break through the limited supply of the receptor's quantity. As a proof of concept, three metal NPs, i.e., Au, Ag, and Pd NPs, were taken as examples to deposit on PPy@MoS2 as colorimetric probes to construct a cross-reactive sensor array. Based on the principal component analysis (PCA), the proposed MNN sensor array could well discriminate 11 proteins with unique fingerprint-like patterns at a concentration of 250 nM and was sufficiently sensitive to determine individual proteins with a detection limit down to the nanomolar level. Remarkably, two highly similar hemoglobins from different species (hemoglobin and bovine hemoglobin) have been precisely identified. Additionally, five oral bacteria were also well separated from each other without cross-classification at the level of 107 CFU mL-1. Furthermore, the sensor array allowed effective discrimination of complex protein mixtures either at different molar ratios or with minor varying components. Most importantly, the blind samples, proteins in human serums, proteins in simulated body fluid environment, the heat-denatured proteins, and even clinical cancer samples all could be well distinguished by the sensor array, demonstrating the real-world applications in clinical diagnosis.

Heat-denatured protein analysis by SDS-PAGE with low concentration of SDS. in the extraction medium

Heat-denatured protein analysis by SDS-PAGE with low concentration of SDS. in the extraction medium

Heat-denatured and alcalase-hydrolyzed protein films/coatings containing marjoram essential oil and thyme extract

In this study, heat-denatured and alcalase-hydrolyzed whey and soy protein films/coatings containing marjoram essential oil (MEO) and thyme extract (TE) were investigated comparatively in terms of physicochemical and functional properties. Heat-denaturated high protein solutions produced self-standing, smooth, transparent and viscoelastic films in the presence of glycerol. Enzymatic hydrolysis provided transparency, elasticity and extensibility to the films of low protein solutions. The addition of MEO and TE triggered hardness and brittleness especially in hydrolyzed high protein films and remarkably changed film color, thickness and viscosity possibly affecting surface adherence of films. Heat denatured films exhibited higher water vapor permeability (WVP) than alcalase-hydrolyzed ones. The lowest hardness was obtained in hydrolyzed low protein films with considerable adhesiveness. Hydrolyzed protein solutions coated to cheese provided better protection against moisture loss and MEO added films caused elevated hardening of cheese. MEO and TE incorporated in film matrices were seemed to suppress mycelial growth and sporulation of Aspergillus niger. This study presented valuable new findings on functional protein films produced by enzymatic hydrolysis as an alternative to heat treatment.

COVID-19 vaccine mRNA-1273 elicits a protective immune profile in mice that is not associated with vaccine-enhanced disease upon SARS-CoV-2 challenge

Vaccine-associated enhanced respiratory disease (VAERD) was previously observed in some preclinical models of severe acute respiratory syndrome (SARS) and MERS coronavirus vaccines. We used the SARS coronavirus 2 (SARS-CoV-2) mouse-adapted, passage 10, lethal challenge virus (MA10) mouse model of acute lung injury to evaluate the immune response and potential for immunopathology in animals vaccinated with research-grade mRNA-1273. Whole-inactivated virus or heat-denatured spike protein subunit vaccines with alum designed to elicit low-potency antibodies and Th2-skewed CD4+ T cells resulted in reduced viral titers and weight loss post challenge but more severe pathological changes in the lung compared to saline-immunized animals. In contrast, a protective dose of mRNA-1273 induced favorable humoral and cellular immune responses that protected from viral replication in the upper and lower respiratory tract upon challenge. A subprotective dose of mRNA-1273 reduced viral replication and limited histopathological manifestations compared to animals given saline. Overall, our findings demonstrate an immunological signature associated with antiviral protection without disease enhancement following vaccination with mRNA-1273.