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Quaternary cationic surfactants with bactericidal activity such as Didecyldimethylammonium chloride (DDAC) show an inactivation effect on enveloped viruses, but they have little effect on non-enveloped viruses such as noroviruses. Therefore, we examined additives that enhance the inactivation effect of cationic surfactants by using Feline calicivirus (FCV) as a representative of a non-enveloped virus. The result was that SO42- ions, which are a general-purpose salt, had a strong salting-out effect that reduced the solubility of proteins, greatly enhancing the inactivation ability of DDAC. The SO42- ions also enhanced FCV inactivation by other cationic surfactants such as Cetylpyridinium Chloride (CPC) and Benzalkonium chloride (ADBAC). To clarify the mechanism, we evaluated the denaturation and binding process of DDAC to Bovine Serum Albumin (BSA) as a model protein by means of Circular Dichroism (CD) spectrum and Isothermal Titration Calorimeter (ITC), respectively. The SO42- ions disturbed the protein structure by their salting- out effect and promoted cooperative binding from lower DDAC concentrations by reducing the Critical Micelle Concentration (CMC), indicating that these synergistic effects caused a large structural change in the protein. These results suggested that increasing the protein denaturation of the cationic surfactants by adding SO42- ions enhanced the inactivation effect on the non-enveloped virus. [ABSTRACT FROM AUTHOR]

The functional structure of proteins results from marginally stable folded conformations. Reversible unfolding, irreversible denaturation, and deterioration can be caused by chemical and physical agents due to changes in the physicochemical conditions of pH, ionic strength, temperature, pressure, and electric field or due to the presence of a cosolvent that perturbs the delicate balance between stabilizing and destabilizing interactions and eventually induces chemical modifications. For most proteins, denaturation is a complex process involving transient intermediates in several reversible and eventually irreversible steps. Knowledge of protein stability and denaturation processes is mandatory for the development of enzymes as industrial catalysts, biopharmaceuticals, analytical and medical bioreagents, and safe industrial food. Electrophoresis techniques operating under extreme conditions are convenient tools for analyzing unfolding transitions, trapping transient intermediates, and gaining insight into the mechanisms of denaturation processes. Moreover, quantitative analysis of electrophoretic mobility transition curves allows the estimation of the conformational stability of proteins. These approaches include polyacrylamide gel electrophoresis and capillary zone electrophoresis under cold, heat, and hydrostatic pressure and in the presence of non-ionic denaturing agents or stabilizers such as polyols and heavy water. Lastly, after exposure to extremes of physical conditions, electrophoresis under standard conditions provides information on irreversible processes, slow conformational drifts, and slow renaturation processes. The impressive developments of enzyme technology with multiple applications in fine chemistry, biopharmaceutics, and nanomedicine prompted us to revisit the potentialities of these electrophoretic approaches. This feature review is illustrated with published and unpublished results obtained by the authors on cholinesterases and paraoxonase, two physiologically and toxicologically important enzymes. [ABSTRACT FROM AUTHOR]

This study aimed to compare the anti-inflammatory effects of fucoidans from brown seaweeds (Saccharina japonica (SJ), Fucus vesiculosus (FV), Fucus distichus (FD), Fucus serratus (FS), and Ascophyllum nodosum (AN)), and determine the relationship between composition and biological activity. The anti-inflammatory activity was tested in vitro. It is believed that inflammation could be triggered by free radicals. Fucoidans from F. vesiculosus (FV1 and FV3) showed the strongest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity with an IC50 = 0.05 mg/mL. In the total antioxidant capacity (TAC) test, the activity was concentration-dependent. Notable, the TAC of fucoidans except samples of FV2 and SJ (which have a lower phenolic content) was higher than that of phloroglucinol. The TAC of fucoidans strongly and positively correlated with polyphenol content. A weak correlation was associated with xylose content. The synergistic effect for fucoidans was calculated for the first time using carbohydrates and polyphenols as model mixtures. The synergy in the DPPH test was found only for FV1 and FV3 (mixture effect ME = 2.68 and 2.04, respectively). The ME strongly positively correlated with polyphenols. The relationship of ME with fucose content was positive but moderate. It was first established that the anti-inflammatory effects of fucoidan could be mediated via the inhibition of protein denaturation. The inhibition was concentration-dependent and strongly correlated with the fucose content and moderate with sulfate content. The purified fucoidan FV2 showed the most promising activity (IC50 = 0.20 mg/mL vs. IC50 = 0.37 mg/mL for diclofenac sodium). Similar relations were also observed in the membrane protection model. Fucoidans were able to stabilize the cell membrane integrity of human red blood corpuscles (HRBC). The results of our study support the rationality of fucoidan use as a promising agent for the treatment of inflammatory-related diseases via mechanisms of radical scavenging, antioxidant activity, inhibition of protein denaturation, and HRBC membrane stabilization. [ABSTRACT FROM AUTHOR]

Protein quality affects the nutritional values and functional properties of protein products. For better utilization, it is important to assess protein quality accurately and cost‐effectively. For decades, several indirect indices have been relied on, including nitrogen solubility index, protein dispersibility index, urease activity, and protein solubility in 0.2% potassium hydroxide. However, each existing index has limitations or practical difficulties for measurement, while different procedures and terminologies often cause confusion. For rectifying this situation, a new protein quality index, the protein solubility index (PSI), was developed. This required investigation of many factors, including alkali hydroxide type and concentration, solid to solvent ratio, extraction time, magnetic stirring speed, magnetic stirrer type, and centrifugation force and time. For nitrogen analysis, a combustion method was used, where effects of using extracts or residues, sample moisture, sample mass, and the sequence of drying and weighing residues were also investigated. The new PSI method employs 5 mM alkali hydroxide extraction, magnetic stirring, nitrogen analysis of dried residues and small sample size. It allows simultaneous running of multiple samples. Furthermore, the correlations between trypsin inhibitor activity (TIA) and PSI were either strong or very strong (r = 0.747**–0.974**), depending on sample sets. The 5 mM extraction procedure produced a stronger correlation between protein extractability and TIA than the extraction procedure for the TIA assay (10 mM NaOH, 3 h). PSI has a potential to replace most, if not all, of the indirect indices for protein quality of various products, providing a unified index for relevant industries. [ABSTRACT FROM AUTHOR]

Gastric milk protein coagulation has been extensively studied using in vitro and animal models. Yet, verifying these results in humans remains essential. In this study, we assessed the feasibility of using MT MRI for monitoring milk protein coagulation in vivo in humans. Twelve adults underwent MRI scans before and after ingesting 300 g of milk with low- or high-protein denaturation (LPD or HPD, respectively). We assessed coagulation and gastric emptying dynamics by deriving the MT ratio (MTR), total gastric content (TGC), semi-solid, and liquid volumes. The MTR values increased during digestion for both milk products, indicating an increase in the degree of coagulation. Prolonged heating of milk did not affect the MTR (MD = 16 %, 95 % CI [10-21], p = 0.15), but resulted in higher TGC volumes (MD 40.3 mL, 95 % CI [25.5-55.1], p = 0.044), indicating slower gastric emptying. We thus showed that by combining MT with conventional anatomical MRI both milk protein coagulation and gastric emptying dynamics, and thereby the impact of heating on gastric milk digestion, can be assessed in vivo in humans. Our work underpins the feasibility of using MRI as a non-invasive imaging tool for studying the effects of food processing and composition on gastric digestion., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: John van Duynhoven has an employment with a company (Unilever) that uses dairy ingredients to manufacture food products. The other authors declare that they have no competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Freeze-drying is a preservation method known for its effectiveness in dehydrating food products while minimizing their deterioration. However, protein denaturation and oxidation during freezing and drying can degrade the quality of meat and aquatic products. Therefore, finding the strategies to ensure the dried products' sensory, functional, and nutritional attributes is crucial. This study aimed to summarize protein denaturation mechanisms and overall quality changes in meat and aquatic products during freezing and drying, while also exploring methods for quality control. Different freeze-drying conditions result in varying levels of oxidation and functionality in meat and aquatic products, leading to changes in quality, such as altered fatty and amino acid compositions, protein digestibility, and sensory attributes. To obtain high-quality dried products by freeze-drying, several parameters should be considered, including sample type, freezing and drying temperatures, moisture content, pulverization effects, and storage conditions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Mitigating the cold denaturation of gluten protein during frozen storage is crucial for the quality improvement of frozen cereal products. Our previous study observed that starch derivatives, especially short-clustered maltodextrin (SCMD), could significantly improve frozen dough quality, alleviating the deterioration of gluten-network structure. To further reveal the cryoprotection mechanism of SCMD on gluten protein during frozen storage, the modulatory roles of SCMD in the hydration capacity and conformation behavior of gluten protein were explored, in comparison with DE2 maltodextrin (MD) and pregelatinized starch (PGS). Results demonstrated that SCMD significantly facilitated the reservation of bound water and decreased the surface hydrophobicity of gluten protein after 8 weeks of frozen storage. Remarkable effects of SCMD on stabilizing the secondary structure and microenvironment of aromatic amino acids of gluten protein were observed. Further mechanistic investigation showed that when the temperature dropped from 300 to 250 K, the short-clustered structure could stabilize the α-helixes more evidently than linear structures through hydrogen bonds with water and steric hindrance effect, rather than directly with protein. Our findings will provide novel insights into the cold denaturation of gluten protein and useful guidance in selecting the optimum structure to suppress this denaturation, improving the quality of frozen cereal products.

Development of monoclonal and bispecific antibody-based protein therapeutics requires detailed characterization of native disulfide linkages, which is commonly achieved through peptide mapping under non-reducing conditions followed by liquid chromatography-mass spectrometry (LC-MS) analysis. One major challenge of this method is incomplete protein digestion due to insufficient denaturation of antibodies under non-reducing conditions. For a long time, researchers have explored various strategies with the aim of efficiently digesting antibody drugs when the disulfide bonds remain intact, but few could achieve this by using a simple and generic approach with well controlled disulfide scrambling artifacts. Here, we report a simple method for fast and efficient mapping of native disulfides of monoclonal and bispecific antibody-based protein therapeutics. The method was optimized to achieve optimal digestion efficiency by denaturing proteins with 8 M urea plus 0-1.25 M guanidine-HCl at elevated temperature (50 °C), followed by two-step digestion with trypsin/Lys-C mix using a one-pot reaction. The only parameter that needs to be optimized for different proteins is the concentration of guanidine-HCl present. This simplified sample preparation eliminated buffer exchange and can be completed within three hours. By using this new method, all native disulfide bonds were confirmed for these monoclonal and bispecific antibodies with high confidence. When compared with a commercial kit utilizing low-pH digestion condition, the new method demonstrated higher digestion efficiency and shorter sample preparation time. These results suggest this new one-pot-two-step digestion method is suitable for the characterization of antibody disulfide bonds, particularly for those antibodies with digestion-resistant domains under typical digestion conditions., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Liqing Gu reports financial support was provided by Incyte Corporation. Tiger X. Hu reports financial support was provided by Incyte Corporation. Liqing Gu reports a relationship with Incyte Corporation that includes: employment and equity or stocks. Tiger X. Hu reports a relationship with Incyte Corporation that includes: employment and equity or stocks., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Plasticizer and thermal denaturation are indeed important factors for soybean protein film formation. The objective of the study was to investigate the effects of glycerol and thermal denaturation on the film-forming performances of soybean protein isolate (SPI) and elucidate the underlying mechanisms. From the results, glycerol had almost no effect on the protein's secondary and tertiary structures. Indeed, the dispersion of glycerol diminished the intra- or intermolecular hydrogen bonding of SPI and interacted with the amino acids of subunits through hydrogen bonding and van der Waals forces. By interfering with protein network interactions, the glycerol molecule achieved a plasticizing effect on SPI films. The effects of heat treatment on SPI film properties were mainly realized through the changes in molecular conformation caused by protein denaturation, which manifested in the enhancement of light barrier and mechanical capabilities, and markedly altered the distribution of water states within the film network. This study provided valuable insights to clarify the mechanism of protein film formation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The formation of inclusion bodies (IBs) in microbial cell factories is a very common process occurring during recombinant protein production. Different protocols have been developed for the extraction of soluble proteins from IBs using several strategies, ranging from the use of harsh denaturing and high concentrations of chaotropic agents and reducing agents to the use of mild protocols based on the use of non-denaturing detergents. However, in recent years, the biological vision of IBs has changed and research studies have demonstrated that these protein aggregates contain biologically active and properly folded recombinant proteins. This drives us to redefine the methodologies currently used to obtain soluble protein using IB as a protein source. Hence, we propose the extraction of IB protein via the simple spontaneous solubilization of IB as a strategy broadly applicable to all kinds of recombinant proteins without the negative effects of detergents and chaotropic agents on final biological activity. We prove the wide applicability of spontaneous solubilization processes to different types of IBs and that protocols can be easily customized for each protein in terms of timing and incubation temperature by monitoring the protein activity of the solubilized fraction., (© 2024. The Author(s).)

Idiopathic pulmonary fibrosis (IPF) is a progressive, life-threatening disease with no early detection, few treatments, and dismal outcomes. Although collagen overdeposition is a hallmark of lung fibrosis, current research mostly focuses on the cellular aspect, leaving collagen, particularly its dynamic remodeling ( i.e ., degradation and turnover), largely unexplored. Here, using a collagen hybridizing peptide (CHP) that specifically binds unfolded collagen chains, we reveal vast collagen denaturation in human IPF lungs and delineate the spatiotemporal progression of collagen denaturation three-dimensionally within fibrotic lungs in mice. Transcriptomic analyses support that lung collagen denaturation is strongly associated with up-regulated collagen catabolism in mice and patients. We thus show that CHP probing differentiates remodeling responses to antifibrotics and highlights the resolution of established fibrosis by agents up-regulating collagen catabolism. We further develop a radioactive CHP that detects fibrosis in vivo in mice as early as 7 days postlung-injury (Ashcroft score: 2-3) by positron emission tomography (PET) imaging and ex vivo in clinical lung specimens. These findings establish collagen denaturation as a promising marker of fibrotic remodeling for the investigation, diagnosis, and therapeutic development of pulmonary fibrosis.

Achilles tendinopathy is often attributed to overuse, but its pathophysiology remains poorly understood. Disruption to the molecular structure of collagen is fundamental for the onset and progression of tendinopathy but has mostly been investigated in vitro. Here, we interrogated the in vivo molecular structure changes of collagen in rat Achilles tendons following treadmill running. Unexpectedly, the tendons' collagen molecules were not mechanically unfolded by running but denatured through proteolysis during physiological post-run remodeling. We further revealed that running induces inflammatory gene expressions in Achilles tendons and that long-term running causes prolonged, elevated collagen degradation, leading to the accumulation of denatured collagen and tendinopathy development. For applications, we demonstrated magnetic resonance imaging of collagenase-induced Achilles tendon injury in vivo using a denatured collagen targeting contrast agent. Our findings may help close the knowledge gaps in the mechanobiology and pathogenesis of Achilles tendinopathy and initiate new strategies for its imaging-based diagnosis.

Collagen, a widely used biomaterial, is susceptible to denaturation during production from native tissues, posing serious challenges for its applications in tissue engineering. Accurate quantification of denatured collagen (DC) is essential for evaluating the quality of collagen-based biomaterials, yet quantitative methods for assessing collagen denaturation are lacking. Here, we for the first time present a highly specific biochip for sensitive quantification of denatured collagen levels ( L dc ), addressing this critical need in collagen quality analysis. The denatured collagen-specific chip (DCSC) features an intrinsically nontrimerizing peptide probe, F-GOP-14, targeting denatured collagen and a fully denatured collagen-coated capture surface. The DCSC demonstrates exceptional sensitivity and accuracy in quantifying DC concentration ( C dc ) and total collagen concentration ( C tc ), enabling precise calculation of L dc . Importantly, DCSC is versatile, detecting L dc across various denaturing scenarios, including UV radiation, thermal environments, and decellularization. This denatured collagen-specific biochip offers a robust method for accurately analyzing L dc , with significant potential for enhancing collagen quality assessment in biomaterial development and production.

Pickering emulsions were co-stabilized by nanoliposome (NL) and thermally denatured ovalbumin (DOVA) based on the induction of OVA with strong particle characteristics through thermal denaturation. DOVA-NL particles were spherical and their sizes were mainly distributed between 50 and 100 nm. The surface tension and interfacial tension of DOVA-NL were significantly reduced, and the surface hydrophobicity, amphiphilicity and free -SH content of DOVA were enhanced after complexation with NL. The content of α-helix and β-sheet in DOVA decreased, whereas the content of β-turn and random coil increased after complexation with NL. Hydrophobic interactions, hydrogen bonding and electrostatic forces played a vital role in the interactions between NL and DOVA, leading to conformational changes in DOVA. The number of binding sites between NL and DOVA was more than one, and the interaction between NL and DOVA was exothermic and spontaneous. The emulsification index showed that DOVA-NL-stabilized Pickering emulsions (DNPE) were significantly more stable than DOVA-stabilized emulsions. DOVA-NL particles adsorbed at the oil-water interface and the droplet size of DNPE was smaller than that of DOVA-stabilized emulsions. This study suggests that it may be an effective strategy to improve the stability of Pickering emulsions through co-stabilization with NL and DOVA., Competing Interests: Declaration of competing interest We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Introduction: Inflammation is body’s immune response to harmful stimulus. Commonly used conventional anti-inflammatory agents are Non-Steroidal Anti-inflammatory Drugs (NSAIDs). But on prolonged long-term use, it causes serious adverse events. So, the search towards natural agents which have anti-inflammatory property are increasing nowadays. Sinapis arvensis is an annual flowering plant which has proven multipurpose medicinal phytoconstituents. Aim: To evaluate in-vitro anti-inflammatory effects of flower extracts of Sinapis arvensis with diclofenac as standard. Materials and Methods: This in-vitro study assessed the laboratory based anti-inflammatory activity, performed using Bovine Serum Albumin (BSA) assay in December 2021 at Sree Balaji Medical College and Hospital, Chennai, Tamil Nadu, India. BSA at pH of 6.8 generated denatured proteins. The anti-inflammatory activity of the sample (flower extracts of Sinapis arvensis) and standard (Diclofenac) was assessed by adding to BSA and percentage of inhibition of denaturation were calculated using the formula based on the absorbance measured. Descriptive statistics was used for analysis of collected data. Results: The concentration-dependent inhibition of protein denaturation was observed for both Sinapis arvensis and Diclofenac. At 100 μg concentration, percentage of inhibition reached up to 81.8% and 100% for Sinapis arvensis and Diclofenac, respectively. Conclusion: The present study showed that flower extracts of Sinapis arvensis exhibited concentration dependent anti-inflammatory property invitro which proves to be nearly equivalent with that of the standard Diclofenac.

Physicochemical, proteomics, and bioinformatics analyses were conducted to investigate protein profiles in Trichiurus haumela under frozen (120 d) and chilled (6 d) storage. Springiness, chewiness, myofibrillar active sulfhydryl content, and Ca2+-ATPase activity significantly decreased, suggesting that cold stress altered muscle proteins. Compared with fresh hairtail (FH), 66 common differentially abundant proteins (DAPs) had lower abundances in chilled (3 d; CSH) and frozen (120 d; FSH) hairtail, including myosin binding proteins, filamins, actinin, troponin, and muscle-restricted coiled-coil protein. Gene Ontology (GO) annotation showed DAPs were mainly involved in cellular process, cellular anatomical entity, intracellular, and binding items. Eukaryotic orthologous group (KOG) analysis revealed that changes in cytoskeleton and energy production and conversion functions dominated during cold storage, degrading the myofibril and connective tissue structures and the physicochemical performance of muscle tissues. This study presents deep insights into the protein alternation mechanisms in hairtail muscle under cold stress.

Marination is a common technology in meat processing with advantages of enhancing tenderness, water retention, and overall quality. This study was conducted to investigate the effect of vacuum tumbling and immersion marination on meat quality, microstructure, water mobility, protein changes, and denaturation of Xueshan chicken. Results showed that vacuum tumbling significantly increased the marinating rate of chicken, tenderness, meat texture, and water retention. Meanwhile, vacuum tumbling decreased total sulfhydryl content alongside an increased protein surface hydrophobicity and free sulfhydryl content, indicating that vacuum tumbling elevated the degree of protein denaturation. Further, the peak area corresponding to the relaxation time T22 after vacuum tumbling was significantly higher than that of immersion marination, suggesting that the stability of the immobilized water of chicken was reduced by vacuum tumbling. Compared to immersion marination, vacuum tumbling improved myofibril fragmentation index (MFI) presenting fewer myofibrillar protein bands in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) gel and more damaged muscular cells. Overall, vacuum tumbling could improve the marination absorptivity, protein degradation, and denaturation, resulting in changes in myofibril structure and meat quality of Xueshan chicken.

This study was conducted on chicken pectoralis major muscle with different wooden breast severity in combination with different sampling locations to investigate the effects of wooden breast syndrome on protein traits and total myofiber area, and their associations. Contents of sarcoplasmic, salt-soluble myofibrillar and salt-insoluble protein and proportion of total myofiber area significantly declined with increasing severity in the superficial part of muscle, whereas the amount of heat-soluble/insoluble collagen and protein denaturation as well as the area of degenerated myofibers, connective tissue and cellular infiltrates increased. Myofibril protein content indicators showed strong positive correlations to total myofiber area. Moreover, PCA results indicated that severe wooden breast is positively linked to muscle collagen content and to protein denaturation. Our results suggest that decrease in sarcoplasmic and myofibrillar proteins is associated with reduction of myofiber area. In turn, the muscle fibers are replaced by connective tissue, accompanied by excessive myofibrillar and sarcoplasmic protein denaturation.

Storage via freezing remains the most effective approach for fish preservation. However, lipid oxidation and protein denaturation still occur during storage, along with nutritional loss. The extent of lipid alteration and protein denaturation are associated with human health defects. To precisely predict common carp (Cyprinus carpio) nutritional quality change during frozen storage, here, we first determined lipid oxidation and hydrolysis and protein denaturation of common carp fillets during 17 weeks of frozen preservation at 261 K, 253 K, and 245 K. Results showed that the content of thiobarbituric acid reactive substances (TBARS) and free fatty acids (FFA) were significantly increased. However, salt-soluble protein (SSP) content, Ca2+-ATPase activity, and total sulfhydryl (SH) content kept decreasing during frozen storage, with SSP content decreasing by 64.82%, 38.14%, and 11.24%, respectively, Ca2+-ATP enzyme activity decreasing to 12.50%, 18.52%, and 28.57% Piμmol/mg/min, and SH values decreasing by 70.71%, 64.92%, and 56.51% at 261 K, 253 K, and 245 K, respectively. The values at 261 K decreased more than that at 253 K and 245 K (p < 0.05). Ca2+-ATPase activity was positively correlated (r = 0.96) with SH content. Afterwards, based on the results of the above chemical experiments, we developed a radial basis function neural network (RBFNN) to predict the modification of lipid and protein of common carp fillets during frozen storage. Results showed that all the relative errors of experimental and predicted values were within ±10%. In summary, the quality of common carp can be well protected at 245 K, and the established RBFNN could effectively predict the quality of the common carp under frozen conditions at 261–245 K.

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Summary: The mechanism of protein denaturation of frozen surimi enriched with soluble soybean polysaccharides (SSPS) was investigated. Near‐infrared (NIR) and hyperspectral imaging (HSI) technology were used to predict protein denaturation. The fresh grass carp surimi was divided into four groups with SSPS additions of 0%, 1%, 3% and 5%, respectively, which were frozen and stored at −18 °C. Samples were examined after 0, 1, 2, 4 and 8 weeks, for salt‐soluble protein content, total SH, NIR hyperspectral image and Raman spectrum features. The results showed that addition of SSPS decelerated protein degradation. After 8 weeks of storage, the 5% SSPS addition maintained the highest salt‐soluble protein content, while for total SH, 3% and 5% SSPS addition had similar effect. Raman spectra illustrated that SSPS had the ability of maintaining an α‐helix content, as well as decreasing the exposure of polar groups, and reducing the oxidation of SH group into disulphide bonds. NIR spectra showed that the overall reflectance of frozen surimi increased with the increase in SSPS. Two partial least squares regression (PLSR) models were established after pretreatment of HSI spectral statistics and selection of characteristic wavelengths. The distribution maps were finally generated based on the simplified PLSR models. [ABSTRACT FROM AUTHOR]

Surimi is a protein concentrate formed basically by fish myofibrillar proteins. For better quality conservation, natural or synthetic cryoprotectants, with emphasis on sucrose, sorbitol and/or sodium tripolyphosphate are added to surimi. Studies show that it is possible to replace these synthetic additives and offer a final product with healthier properties to the consumer. This review highlights the importance of reducing the use of synthetic additives in the conservation of surimi and suggests potential natural alternatives for the total or partial replacement of these artificial substances, as well as discussing the effects of different types of natural compounds on the quality characteristics of surimi gel. [ABSTRACT FROM AUTHOR]

This paper presents a differential-mode microwave microfluidic sensor useful for the characterization/detection of the denaturation of Bovine Serum Albumin (BSA), a protein with numerous biochemical applications, caused by a chaotropic agent, specifically, urea. The sensor consists of a pair of uncoupled microstrip lines, each one loaded with a transversally oriented slot resonator, etched in the ground plane. The sensor is a device able to detect permittivity changes in the so-called material under test (MUT), or liquid under test (LUT), as compared to a reference (REF) material/liquid. However, since the changes in the permittivity of the BSA caused by the denaturation process are partially obscured by the presence of the urea in the LUT, a protocol to separate the effects of the urea in the sample is proposed. According to such protocol, two different BSA samples, with different concentrations, are needed. It is shown that, with such a method, the denaturation process can be detected and characterized through the so-called hydration contrast, related to the measured difference of the output variables (the cross-mode transmission coefficient) in both BSA samples. The reported protocol and denaturation detection method based on differential-mode microwave sensing, which has never been reported so far, provides hydration contrasts of 0.06 for 6M urea concentrations. [ABSTRACT FROM AUTHOR]

Almonds (Prunus dulcis) seeds, from the Rosaceae family, have been reported to contain essential nutrients that reduced inflammation by lowering certain inflammatory markers. This study evaluated the anti-inflammatory activity of P. dulcis (Almond seed) extract and fractions (n-hexane and aqueous). Dried almond seed (700 g) was pulverized and soaked in distilled water for 24 hrs. The aqueous extract was filtered and the filtrate was lyophilized to obtain the seed aqueous crude extract. The crude extract portion was dissolved in water, partitioned with n-hexane and separately concentrated to dryness to obtain the aqueous and n-hexane fractions. Anti-inflammatory activity of almond seed extract and fractions were carried out via erythrocyte membrane stabilization, antitryptic and protein denaturation inhibitory assays. Results obtained shows that n-hexane fraction of P. dulcis seed stabilized stressed erythrocyte maximally (18.70 ± 3.23%) at 2.00 mg/mL and aqueous fraction (16.72 ± 1.97%) at 0.5 mg/mL, while aqueous extract highest % stability was 17.73± 2.32% at 2.00 mg/mL. Also, n-hexane fraction inhibited trypsin better at higher concentrations while the aqueous fraction was at a lower concentration. However, both showed better anti-tryptic activity than aqueous crude extract.Moreover, maximum percentage protein inhibitory activities for diclofenac (800 µg/ml), aqueous fraction (800 µg/ml), n-hexane fraction (1600 µg/ml) and aqueous extract (1600 µg/ml) were 72, 51, 35 and 32 respectively.This study concludes that almond seed fractions showed better anti-inflammatory activity compared to their crude extract. Therefore, the isolation of active compounds from these fractions may provide a novel antiinflammatory drug. [ABSTRACT FROM AUTHOR]

Due to its unique properties and high biomedical relevance fibrinogen is a promising protein for the development of various matrixes and scaffolds for biotechnological applications. Fibrinogen molecules may form extensive clots either upon specific cleavage by thrombin or in thrombin‐free environment, for example, in the presence of different salts. Here, we report the novel type of non‐conventional fibrinogen clot formation, which is mediated by myeloperoxidase and takes place even at low fibrinogen concentrations (<0.1 mg/ml). We have revealed fibrillar nature of myeloperoxidase‐mediated fibrinogen clots, which differ morphologically from fibrin clots. We have shown that fibrinogen clotting is mediated by direct interaction of myeloperoxidase molecules with the outer globular regions of fibrinogen molecules followed by fibrinogen unfolding from its natural trinodular to a fibrillar structure. We have demonstrated a major role of the Debye screening effect in regulating of myeloperoxidase‐induced fibrinogen clotting, which is facilitated by small ionic strength. While fibrinogen in an aqueous solution with myeloperoxidase undergoes changes, the enzymatic activity of myeloperoxidase is not inhibited in excess of fibrinogen. The obtained results open new insights into fibrinogen clotting, give new possibilities for the development of fibrinogen‐based functional biomaterials, and provide the novel concepts of protein unfolding. [ABSTRACT FROM AUTHOR]

The objective of this study was to reveal the effects of boiling processing on the texture of scallop adductor muscle (SAM) and its mechanism. Compared to the fresh sample, all the texture indicators, including the hardness, chewiness, springiness, resilience, cohesiveness, and shear force of 30-s- and 3-min-boiled SAMs increased time-dependently (p < 0.05). As the boiling time increased further to 15 min, the shear force and cohesiveness still increased significantly (p < 0.05), and the resilience and hardness were maintained (p > 0.05), but the springiness and chewiness decreased significantly (p < 0.05). The overall increase in the texture indicators of the boiled SAMs was due to the boiling-induced protein denaturation, aggregation, and increased hydrophobicity, resulting in the longitudinal contraction and lateral expansion of myofibrils, the longitudinal contraction and lateral cross-linked aggregation of muscle fibers, and the loss of free water. However, the decreasing springiness and chewiness of the 15-min-boiled SAMs was due to the significant degradation of proteins (especially collagen), resulting in the destruction of the connective tissue between the muscle fiber clusters. Both from a subjective sensory point of view and from the objective point of view of protein denaturation and degradation, 3-min-boiled SAMs are recommended. The quality improvement of thermally processed products by controlled, moderate cooking is of practical value from the perspective of food consumption. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive 3D printing process for plant-based meat alternatives, covering ink formulation, printing, and final product characterization. Traditionally, achieving desired food properties requires extensive exploration of ink components. Here, we demonstrate the potential of manipulating processing parameters instead of ink composition. Two structures were printed, differing only in extrusion temperature. The printed structures exhibited a dimensional accuracy slightly below 100%. We investigated their behavior through simulated food production cycles, including freezing, thawing, dehydration, and rehydration. Rheological measurements revealed that protein denaturation caused a 20% increase in viscosity. Temperature-induced protein denaturation allowed to produce 3D printed samples with a fine porous structure, with pore sizes ranging from 50 to 450 μm. Mechanical characterization showed that a single printing parameter (extrusion temperature) significantly impacts the final product mechanical properties, with an increase of about 50% in the maximum stress for denatured samples after rehydration. This novel approach simplifies 3D-printed protein-based food production, establishing a link between processing parameters and the final product mechanical behavior. [Display omitted] • Morphology of 3D printed plant based meat analogues changed with processing temperature. • Tuning process temperature lead to different mechanical properties without changing ink composition. • 3D printed porous structures are stable after freezing, desiccation and rehydration. [ABSTRACT FROM AUTHOR]

Food processing, cooking, and consumption introduce various factors that affect food flavor, distinguishing it from its objective composition. This study focuses on liquor-accompanying food pairing, investigating the interaction between baijiu aroma compounds and peanut proteins, and the effect of ethanol on it. Peanut globulins significantly inhibited the release of baijiu aroma compounds through hydrogen bonding (2.63–3.23 Å), hydrophobic interactions, and covalent reactions (−2.85 to −5.64 kcal/mol) , resulting in flavor modification. In the presence of ethanol, peanut globulins adopt a more compact and aggregated structure, reducing their affinity for binding aroma compounds. Surprisingly, this structural change promotes a salting-out effect, significantly promoting the release of aldehydes, phenols, and aromatic compounds, enhancing the grassy, floral, and sweet aroma of baijiu. This finding improves the understanding of alcohol pairing and proposes a novel strategy for enhancing the overall flavor profile of baijiu by modifying accompanying food choices. • Peanut globulin inhibits different baijiu aroma via multiple interactions. • Ethanol in baijiu induces a compact peanut globulin structure. • Denatured peanut globulin produces a salting-out effect. • Denatured peanut globulin enhances baijiu aroma like phenylacetaldehyde. [ABSTRACT FROM AUTHOR]

The quality of meat in prepared dishes deteriorates due to excessive protein denaturation resulting from precooking, freezing, and recooking. This study aimed to link the precooked state with chicken breast's recooked quality. Cooked Value (CV), based on protein denaturation kinetics, was established to indicate the doneness of meat during pre-heating. The effects of CV s after pre-heating on recooked qualities were investigated compared to fully pre-heated samples (control). Mild pre-heating reduced water migration and loss. While full pre-heating inhibited protein oxidation during freezing, intense oxidation during pre-heating led to higher oxidation levels. Surface hydrophobicity analysis revealed that mild pre-heating suppressed aggregation during recooking. These factors contributed to a better texture and microstructure of prepared meat with mild pre-heating. Finally, a potential mechanism of how pre-heating affects final qualities was depicted. This study underlines the need for finely controlling the industrial precooking process to regulate the quality of prepared meat. • Mild pre-heating enhanced final qualities of prepared chicken breasts. • A scale of cooked value for pre-heating degree was established. • Mild pre-heating reduced water loss and enhanced water holding capacity. • Mild pre-heating prevented excessive protein oxidation. • Mild pre-heating decreased protein aggregation during re-cooking. [ABSTRACT FROM AUTHOR]

The protein-folding mechanism remains a major puzzle in life science. Purified soluble activation-induced cytidine deaminase (AID) is one of the most difficult proteins to obtain. Starting from inclusion bodies containing a C-terminally truncated version of AID (residues 1-153; AID153), an optimized in vitro folding procedure was derived to obtain large amounts of AID153, which led to crystals with good quality and to final structural determination. Interestingly, it was found that the final refolding yield of the protein is proline residue-dependent. The difference in the distribution of cis and trans configurations of proline residues in the protein after complete denaturation is a major determining factor of the final yield. A point mutation of one of four proline residues to an asparagine led to a near-doubling of the yield of refolded protein after complete denaturation. It was concluded that the driving force behind protein folding could not overcome the cis-to-trans proline isomerization, or vice versa, during the protein-folding process. Furthermore, it was found that successful refolding of proteins optimally occurs at high pH values, which may mimic protein folding in vivo. It was found that high pH values could induce the polarization of peptide bonds, which may trigger the formation of protein secondary structures through hydrogen bonds. It is proposed that a hydrophobic environment coupled with negative charges is essential for protein folding. Combined with our earlier discoveries on protein-unfolding mechanisms, it is proposed that hydrogen bonds are a primary driving force for de novo protein folding.

In neurons, lysosomes, which degrade membrane and cytoplasmic components, are thought to primarily reside in somatic and axonal compartments, but there is little understanding of their distribution and function in dendrites. Here, we used conventional and two-photon imaging and electron microscopy to show that lysosomes traffic bidirectionally in dendrites and are present in dendritic spines. We find that lysosome inhibition alters their mobility and also decreases dendritic spine number. Furthermore, perturbing microtubule and actin cytoskeletal dynamics has an inverse relationship on the distribution and motility of lysosomes in dendrites. We also find trafficking of lysosomes is correlated with synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type glutamate receptors. Strikingly, lysosomes traffic to dendritic spines in an activity-dependent manner and can be recruited to individual spines in response to local activation. These data indicate the position of lysosomes is regulated by synaptic activity and thus plays an instructive role in the turnover of synaptic membrane proteins.

Samples prepared for single-particle electron cryo-microscopy (cryo-EM) necessarily have a very high surface-to-volume ratio during the short period of time between thinning and vitrification. During this time, there is an obvious risk that macromolecules of interest may adsorb to the air-water interface with a preferred orientation, or that they may even become partially or fully unfolded at the interface. In addition, adsorption of macromolecules to an air-water interface may occur even before thinning. This paper addresses the question whether currently used methods of sample preparation might be improved if one could avoid such interfacial interactions. One possible way to do so might be to preemptively form a surfactant monolayer over the air-water interfaces, to serve as a structure-friendly slide and coverslip. An alternative is to immobilize particles of interest by binding them to some type of support film, which-to continue using the analogy-thus serves as a slide. In this case, the goal is not only to prevent the particles of interest from diffusing into contact with the air-water interface but also to increase the number of particles seen in each image. In this direction, it is natural to think of developing various types of affinity grids as structure-friendly alternatives to thin carbon films. Perhaps ironically, if precautions are not taken against adsorption of particles to air-water interfaces, sacrificial monolayers of denatured protein may take the roles of slide, coverslip, or even both.

Land plant phytochromes perceive red and far-red light to control growth and development, using the linear tetrapyrrole (bilin) chromophore phytochromobilin (PΦB). Phytochromes from streptophyte algae, sister species to land plants, instead use phycocyanobilin (PCB). PCB and PΦB are synthesized by different ferredoxin-dependent bilin reductases (FDBRs): PΦB is synthesized by HY2, whereas PCB is synthesized by PcyA. The pathway for PCB biosynthesis in streptophyte algae is unknown. We used phylogenetic analysis and heterologous reconstitution of bilin biosynthesis to investigate bilin biosynthesis in streptophyte algae. Phylogenetic results suggest that PcyA is present in chlorophytes and prasinophytes but absent in streptophytes. A system reconstituting bilin biosynthesis in Escherichia coli was modified to utilize HY2 from the streptophyte alga Klebsormidium flaccidum (KflaHY2). The resulting bilin was incorporated into model cyanobacterial photoreceptors and into phytochrome from the early-diverging streptophyte alga Mesostigma viride (MvirPHY1). All photoreceptors tested incorporate PCB rather than PΦB, indicating that KflaHY2 is sufficient for PCB synthesis without any other algal protein. MvirPHY1 exhibits a red-far-red photocycle similar to those seen in other streptophyte algal phytochromes. These results demonstrate that streptophyte algae use HY2 to synthesize PCB, consistent with the hypothesis that PΦB synthesis arose late in HY2 evolution.

The increasing availability of high-quality experimental data and first-principles calculations creates opportunities for developing more accurate empirical force fields for simulation of proteins. We developed the AMBER-FB15 protein force field by building a high-quality quantum chemical data set consisting of comprehensive potential energy scans and employing the ForceBalance software package for parameter optimization. The optimized potential surface allows for more significant thermodynamic fluctuations away from local minima. In validation studies where simulation results are compared to experimental measurements, AMBER-FB15 in combination with the updated TIP3P-FB water model predicts equilibrium properties with equivalent accuracy, and temperature dependent properties with significantly improved accuracy, in comparison with published models. We also discuss the effect of changing the protein force field and water model on the simulation results.

Essentially all biochemistry and most molecular biology experiments require recombinant proteins. However, large, hydrophobic proteins typically aggregate into insoluble and misfolded species, and are directed into inclusion bodies. Current techniques to fold proteins recovered from inclusion bodies rely on denaturation followed by dialysis or rapid dilution. Such approaches can be time consuming, wasteful, and inefficient. Here, we describe rapid protein folding using a vortex fluidic device (VFD). This process uses mechanical energy introduced into thin films to rapidly and efficiently fold proteins. With the VFD in continuous flow mode, large volumes of protein solution can be processed per day with 100-fold reductions in both folding times and buffer volumes.

Trimethylamine N-oxide (TMAO), an important intestinal flora-derived metabolite, plays a role in the development of cardiovascular disease and tumor immunity. Here, we determined the minimum inhibitory concentration (MIC) of antibiotics against Escherichia coli under gradient concentrations of TMAO and performed a bacterial killing analysis. Overall, TMAO (in the range of 10 ~ 100 mM) increased the MIC of quinolones, aminoglycosides, and β-lactams in a concentration-dependent manner, and increased the lethal dose of antibiotics against E. coli. It implies that TMAO is a potential risk for failure of anti-infective therapy, and presents a case for the relationship between intestinal flora-derived metabolites and antibiotic resistance. Further data demonstrated that the inhibition of antibiotic efficacy by TMAO is independent of the downstream metabolic processes of TMAO and the typical bacterial resistance mechanisms (mar motif and efflux pump). Interestingly, TMAO protects E. coli from high-protein denaturant (urea) stress and improves the viability of bacteria following treatment with two disinfectants (ethanol and hydrogen peroxide) that mediate protein denaturation by chemical action or oxidation. Since antibiotics can induce protein inactivation directly or indirectly, our work suggests that disruption of protein homeostasis may be a common pathway for different stress-mediated bacterial growth inhibition/cell death. In addition, we further discuss this possibility, which provides a different perspective to address the global public health problem of antibiotic resistance.

• 1,2,4-Triazolium Ionic Liquids are synthesized and characterized. • The solvent nature of the ionic liquids is evaluated through photophysical studies. • The effective intercalation of ionic liquids with beta cyclodextrin is observed. • The ionic liquids are found to be capable in stabilizing serum albumin in their native state. • The alkyl chain of ionic liquid plays a prominent role in their association with organized media. Room temperature ionic liquids (RTILs) are utilized as solvents and catalysts in organic reactions, with applications spanning from electrochemistry to the detergent sector. Researchers extensively study imidazolium ILs for photophysical analysis in many applications. There are limited studies on the synthesis of triazolium-based ILs and their subsequent photophysical characterization. 1-Alkyl-1,2,4-triazolium-based ILs are selected for their adjustable physiochemical characteristics, strong stability, and capacity for recovery and multiple uses. Two ILs were developed in this study: 1-pentyl-1,2,4-triazolium trifluoroacetate (1-pent3HTTFA) and 1-hexyl-1,2,4-triazolium trifluoroacetate (1-hex3HTTFA). We evaluated the solvent properties of the synthesized ILs using coumarin as a fluorescent probe. Additionally, we investigated the microemulsification of the ILs by using β-Cyclodextrin as the heterogeneous medium. Experiments were conducted to investigate how two triazolium-based ILs interacted with bovine serum albumin (BSA) and their ability to prevent protein denaturation. [ABSTRACT FROM AUTHOR]

In view of the merits of all-purpose wheat flour (APWF) to soft wheat flour (SWF) in cost and protein supply, the feasibility of heat-moisture treatment (HMT, 19% moisture for 1 h at 60, 80 and 100 °C, respectively) to modify APWF as a substitute SWF in making short dough biscuits was explored. For underlying mechanisms, on the one hand, HMT reduced the hydration capacity of damaged starch particles by coating them with denatured proteins. On the other hand, HMT at 80 °C and 100 °C significantly denatured gluten proteins to form protein aggregates, highly weakening the gluten network in dough. These two aspects jointly conferred APWF dough with higher deformability and therefore significantly improved the qualities of biscuits. Moreover, the qualities of biscuits from APWF upon HMT-100 °C were largely comparable to that from SWF, even higher values were concluded in spread ratio, volume, specific volume and consumer acceptance. [Display omitted] • Heat-moisture treatment (HMT) modified all-purpose flour for short dough biscuit. • HMT reduced the hydration capacities of flour components, especially that of damaged starch. • HMT weakened starch-starch, protein-starch and protein-protein interactions in dough. • All-purpose flour by HMT-100 °C presented comparable biscuit quality to soft wheat flour. [ABSTRACT FROM AUTHOR]

Muscle protein stability during freeze-thaw (F-T) cycles was investigated with tilapia cultured in recirculating aquaculture systems (RAS) and traditional aquaculture in ponds (TAP). This study found that fatty acids (eg., palmitic acid) were enriched in TAP, while antioxidants (eg., glutathione) were enriched in RAS. Generally, proteins in the RAS group exhibited greater stability against denaturation during the F-T cycle, suggested by a less decrease in haem protein content (77% in RAS and 86% in TAP) and a less increase in surface hydrophobicity of sarcoplasmic protein (63% in RAS and 101% in TAP). There was no significant difference in oxidative stability of myofibrillar protein between the two groups. This study provides a theoretical guide for the quality control of tilapia cultured in RAS during frozen storage. [Display omitted] • Muscle composition of tilapia from different aquaculture system was analyzed. • Metabolomics suggested an enrichment of antioxidants in RAS fish muscle. • Proteins in RAS group had greater stability during the freeze-thaw cycles. [ABSTRACT FROM AUTHOR]

This study confronts challenges from global population growth, focusing on protein supply strains and the environmental impact of traditional animal sources. Delving into unexplored territory, this study investigates the combined effects of pH, concentration, and temperature on the rheological and thermal properties of cowpea protein concentrate (CPC). Steady-state and oscillatory rheological tests, along with differential scanning calorimetric analysis, were conducted to unveil the behavior of CPC solutions. The results revealed sensitivity to protein concentration and shear rate, especially at higher concentrations (>10%), and pH emerged as a critical factor, significantly influencing shear stress and viscosity. The elastic and viscous components of alkaline CPC solutions exhibit weak gel behavior, influenced by both pH and frequency. Temperature-induced changes in viscosity and gelation highlight the interaction between thermal conditions and protein structures. The thermal cycle helps explain changes in molecular interactions induced by temperature, with pH playing a role in influencing gelatinization and denaturation. The denaturation temperature (T d) in the thermograms corresponds to vicilin fractions and emphasizes the prominence of denaturation and gelation at neutral pH, where T d was pH 7 > pH 9 > pH 11. Alkaline pH induced significant structural changes, resulting in a gelation onset temperature below the denaturation onset temperature. This study provides a deeper understanding into the rheological and thermal properties of CPC solutions, emphasizing the roles of concentration, pH, and temperature, useful for various steps of industrial processing, before and after thermal gelation. These findings are important for promoting the use of cowpea proteins in the food industry in response to the evolving needs of a growing global population. [Display omitted] • pH plays a critical role, affecting shear stress, viscosity and elastic behavior. • Protein structure and molecular interaction change viscosity during thermal cycle. • Protein gelation begins before the thermal denaturation onset at alkaline pH. • Alkaline pH induces structural changes that affect gelation and denaturation onsets. • Guidance for the use of cowpea protein concentrates in the industrial sectors. [ABSTRACT FROM AUTHOR]

The cooking of pulses causes gelatinization−melting of starch and denaturation of proteins. These thermal transitions were studied in beans and chickpeas using differential scanning calorimetry (20−160 °C, water contents ranging from 0.2 to 4.0 kg kg−1 dry basis). In the thermogram, the shape and temperature of the transition peaks depended on the water content in starch and protein. The thermogram was analyzed to quantify water distribution between starch and protein, assuming the coexistence of two water populations. After modeling the peaks as Gaussian functions, the distribution of water during heating was modeled as a Weibull distribution with water dependent parameters. Most water was available in protein, and was reallocated from protein to starch during heating. The fraction of water attributed to starch increased from less than 10 % of total water to 35−45 % at the end of cooking. Competition between starch and protein for available water delayed all thermal transitions. • Starch transitions occurs at higher temperatures when mixed with proteins. • Water distribution differs between starch and protein. • In starch−protein mixtures, the protein phase captures the most water. • Water reallocates from protein to starch during heating. • The transitions of starch determine the temperature range of water redistribution. [ABSTRACT FROM AUTHOR]

• CU-IRD displayed marked enhancements in heat and moisture transport efficiency. • CU and IR increased myosin denaturation and water fluidity. • CU destroyed the fiber integrity and improved the texture. • CU-IRD showed the shortest drying time and higher drying uniformity. Drying, as a critical step in the production of air-dried beef, has a direct impact on the quality of the final product. Innovatively, a composite system incorporating contact ultrasound (CU) and infrared radiation (IR) as auxiliary measures within a hot air drying (HAD) framework was built in this research, and the effects of these techniques on the drying kinetics, protein denaturation, and moisture transformation of air-dried beef were investigated. In comparison to HAD treatment, the integrated CU and IR (CU-IRD) system displayed marked enhancements in heat and moisture transport efficiency, thereby saving 36.84% of time expenditure and contributing favorably to the improved moisture distribution of the end-product. This was mainly ascribed to the denaturation of myosin induced by IR thermal effect and the micro-channel produced by CU sponge effect, thus increasing T 2 relaxation time and the proportion of free water. In conclusion, the composite system solved the problem of surface hardening and reduces hardness and chewiness of air-dried beef by 40.42% and 45.25% respectively, but inevitably increased the energy burden by 41.60%. [ABSTRACT FROM AUTHOR]

Passive microwave radiometry (MWR) is a measurement technique based on the detection of passive radiation in the microwave spectrum of different objects. When in equilibrium, this radiation is known to be proportional to the thermodynamic temperature of an emitting body. We hypothesize that living systems feature other mechanisms of emission that are based on protein unfolding and water rotational transitions. To understand the nature of these emissions, microwave radiometry was used in several in vitro experiments. In our study, we performed pilot measurements of microwave emissions from egg whites during denaturation induced by ethanol. Egg whites comprise 10% proteins, such as albumins, mucoproteins, and globulins. We observed a novel phenomenon: microwave emissions changed without a corresponding change in the water's thermodynamic temperature. We also found striking differences between microwave emissions and thermodynamic temperature kinetics. Therefore, we hypothesize that these two processes are unrelated, contrary to what was thought before. It is known that some pathologies such as stroke or brain trauma feature increased microwave emissions. We hypothesize that this phenomenon originates from protein denaturation and is not related to the thermodynamic temperature. As such, our findings could explain the reason for the increase in microwave emissions after trauma and post mortem for the first time. These findings could be used for the development of novel diagnostics methods. The MWR method is inexpensive and does not require fluorescent or radioactive labels. It can be used in different areas of basic and applied pharmaceutical research, including in kinetics studies in biomedicine. [ABSTRACT FROM AUTHOR]

Inflammation is a normal protective reaction against tissue damage caused by physical injury, harmful chemicals, and protein denaturation. Protein denaturation is a process in which proteins lose their tertiary structure and secondary structure due to foreign substances, external compounds, such as strong acids, strong bases, organic salts, organic solvents, and heating. The purpose of this study was to determine the anti-inflammatory activity of ethanol extract and ethyl acetate fraction of the seed coat of Kebiul (Caesalpinia bonduc L.) by calculating the IC50 value of protein denaturation in the sample. The results of the phytochemical test of the ethanol extract of Kebiul seeds contained flavonoids, alkaloids, terpenoids, steroids, saponins, and tannins, while the ethyl acetate fraction only contained tannins and alkaloids. The results of the anti-inflammatory test showed that the highest percent inhibition value of sodium diclofenac, ethanol extract, and ethyl acetate fraction, respectively, at a concentration of 20 ppm was 84.8%; 84.1%; and 50%. The IC50 values of sodium diclofenac, ethanol extract, and ethyl acetate fraction were 5.4 µg/mL; 9.9 µg/mL; and 13.3 µg/mL, respectively. The three samples had percent inhibition values exceeding 20% which indicated that all three can be used as an anti-inflammatory. [ABSTRACT FROM AUTHOR]

In this study, the effect of various heating temperatures (61–70 °C) and times (1–10 min) on physical and chemical properties of liquid egg yolk (LEY) and mayonnaise were investigated. Initially, we found that the increase of LEY protein denaturation was highly correlated with the increase of temperature and time, without causing either protein degradation or aggregation. In addition, the viscosity and particle size of LEY were significantly increased with greater heating temperature and time. Furthermore, the emulsification stability of mayonnaise prepared from thermally processed LEY were significantly better than that of the unheated control group, in particular, the emulsion stability of mayonnaise was higher at a temperature ranging from 62 °C to 68 °C, whereas the emulsion stability decreased above 69 °C. A rheological analysis showed that mayonnaise prepared from thermally processed LEY has higher shear stress when compared with the control group. Indeed, a sharp increase in the shear stress was observed when LEY was heated above 67 °C. Results from storage behavior analysis suggest that mayonnaise prepared from thermally processed LEY failed to affect the chemical qualities of mayonnaise, as evidenced by the fact that acid values and TBA values were not statistically significant with the unheated control group. Microscopic observation indicates that the number of complete oil droplets were significantly reduced at higher heating (70 °C/5 and 10 min) conditions. Finally, the sensory evaluation results suggest that mayonnaise prepared from thermally processed LEY does not influence the appearance, aroma, taste, greasy feeling, and overall acceptance of mayonnaise, as indicated by there being no significant differences between the experimental group and the control group (p > 0.05). We conclude from our study that a combination of heating conditions over 67 °C/5 min can allow the mayonnaise to retain better quality in terms of stability. [ABSTRACT FROM AUTHOR]

Summary: The objective of this study was to assess the effects of ultrasonic‐assisted immersion freezing (UIF) of 0, 15, 30 and 45 W L−1 on the conformation changes of pork myofibrillar protein (MP). The structure and conformation of MP were evaluated, and the solubility, thermal stability and sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) were also discussed. The sample treated with 30 W L−1 (UIF‐30) had the highest total protein solubility (116.6 mg g−1) and thermal denaturation temperature (57.07℃) compared with other treatments. UIF‐30 has higher α‐helix content, and fluorescence intensity together with surface hydrophobicity had insignificant changes compared with the control. In SDS–PAGE, only the sample treated with 45 W L−1 (UIF‐45) showed slight band degradation. In general, UIF‐30 effectively minimised the changes of protein conformation, which may be related to the reduction of mechanical damage to muscle cells caused by rapid freezing to form regular and uniform ice crystals. This is more conducive to reducing pork quality degradation caused by protein freeze denaturation. [ABSTRACT FROM AUTHOR]

The main objective is to effectively denature the autolysis enzymes of C. frondosa on the premise of avoiding the quality deterioration caused by overheating. The effects of the different thermal treatments (blanching at 40–80 °C for 45 min, boiling and steaming at 100 °C for 15–120 min) on the cooking yield, moisture content, protein degradation, texture, and enzyme inactivation were studied, and the inner relationship was investigated by multivariate analysis. The autolysis enzymes of C. frondosa were thermally stable and cannot be denatured completely by blanching. Boiling and steaming could efficiently inactivate the enzymes but overheating for 60–120 min reduced the cooking yield and texture quality. Boiling at 100 °C for 45 min was suitable for pre-treatment, with cooking yield of 70.3% and protein content of 78.5%. Steaming at 100 °C for at least 30 min was preferable for long-term storage and instant food, in which the relative activity was only 3.2% with better palatability. [ABSTRACT FROM AUTHOR]

Summary: The objective of this study was to assess the effects of ultrasonic‐assisted immersion freezing (UIF) of 0, 15, 30 and 45 W L−1 on the conformation changes of pork myofibrillar protein (MP). The structure and conformation of MP were evaluated, and the solubility, thermal stability and sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) were also discussed. The sample treated with 30 W L−1 (UIF‐30) had the highest total protein solubility (116.6 mg g−1) and thermal denaturation temperature (57.07℃) compared with other treatments. UIF‐30 has higher α‐helix content, and fluorescence intensity together with surface hydrophobicity had insignificant changes compared with the control. In SDS–PAGE, only the sample treated with 45 W L−1 (UIF‐45) showed slight band degradation. In general, UIF‐30 effectively minimised the changes of protein conformation, which may be related to the reduction of mechanical damage to muscle cells caused by rapid freezing to form regular and uniform ice crystals. This is more conducive to reducing pork quality degradation caused by protein freeze denaturation. [ABSTRACT FROM AUTHOR]

Chemical chaperones are low-molecular compounds counteracting protein aggregation. Understanding of the mechanism of their effects is key to their potential use in biotechnology. The aggregation of bovine liver glutamate dehydrogenase (GDH) was studied at 40 °C and 50 °C using dynamic light scattering, analytical ultracentrifugation, size-exclusion chromatography and differential scanning calorimetry. At 40 °C the GDH aggregation proceeds through the slow stages of hexamer dissociation and formation of small oligomeric aggregates. At 50 °C these stages are transient. The rate-limiting stage of the overall aggregation process is unfolding of the protein molecule; the order of aggregation with respect to protein, n = 1. The test system based on GDH aggregation at 50 °C was used to quantify the anti-aggregation activity of chemical chaperones by comparing their half-saturation concentrations [L] 0.5. Arginine ethyl ester had the highest anti-aggregation activity, with [L] 0.5 = 4 ± 1 mM. For other additives, [L] 0.5 was 22 ± 1 mM (arginine), 18 ± 1 mM (argininamide) and 95 ± 12 mM (proline). Arginine at concentrations up to 300 mM, argininamide at concentrations higher than 300 mM and arginine ethyl ester at concentrations higher than 500 mM enhance aggregate-aggregate sticking. These results explain the mechanism of heat-induced GDH aggregation and its peculiarities at different temperatures or in the presence of chemical chaperones. • Glutamate dehydrogenase (GDH) aggregates via irreversible dissociation and oligomerization. • The rate-limiting stage is unfolding of the protein molecule. • All the additives studied stabilize native GDH, its dissociated forms and small aggregates. • Arginine ethyl ester had the highest anti-aggregation activity, [L] 0.5 = 4 ± 1 mM. [ABSTRACT FROM AUTHOR]

Background: Antioxidants are chemical substances, either synthetic or natural, that can avert or slow down a range of cellular damage. Objectives: The purpose of this study was to verify the antioxidant and anti-inflammatory properties of alcoholic and aqueous extracts of Ficus infectoria fruits. Materials and Methods: DPPH free radical quenching test, reducing power technique, and hydrogen peroxide scavenging tests were used to assess antioxidant efficacy. In vitro anti-inflammatory experiments were also investigated for membrane stabilization potential and inhibition of proteins from denaturation. Results: Fruits included alkaloids, steroids, phenolics, flavonoids, and amino acids, according to phytochemical study. The total phenolic and flavonoid content of the methanolic and aqueous preparations were determined to be 576.16 ± 129.10 and 416.12 ± 112.01 mg/g Gallic Acid Equivalents (GAE) and 423.17 ± 56.48 and 253.35 ± 24.07 mg/g Rutin Equivalents (RE) respectively. In comparison to the benchmarks Rutin and ascorbic acid, both preparations showed significant DPPH and H2O2 quenching efficacy. As compared to the standard Indomethacin, both preparations have strong membrane stabilising and protein denaturation inhibitory potencies Conclusion: The current findings point to Ficus infectoria's antioxidant and anti-inflammatory properties. However, the active ingredients relevant for the activity must be identified and purified, and the exact mechanism must be determined. [ABSTRACT FROM AUTHOR]