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Bioscience Reports May 2024The rotavirus capsid protein VP6 forms the middle of three protein layers and is responsible for many critical steps in the viral life cycle. VP6 as a structural protein...
The rotavirus capsid protein VP6 forms the middle of three protein layers and is responsible for many critical steps in the viral life cycle. VP6 as a structural protein can be used in various applications including as a subunit vaccine component. The head domain of VP6 (VP6H) contains key sequences that allow the protein to trimerize and that represent epitopes that are recognized by human antibodies in the viral particle. The domain is rich in β-sheet secondary structures. Here, VP6H was solubilised from bacterial inclusion bodies and purified using a single affinity chromatography step. Spectral (far-UV circular dichroism and intrinsic tryptophan fluorescence) analysis revealed that the purified domain had native-like secondary and tertiary structures. The domain could maintain structure up to 44°C during thermal denaturation following which structural changes result in an intermediate forming and finally irreversible aggregation and denaturation. The chemical denaturation with urea and guanidinium hydrochloride produces intermediates that represent a loss in the cooperativity. The VP6H domain is stable and can fold to produce its native structure in the absence of the VP6 base domain but cannot be defined as an independent folding unit.
Topics: Capsid Proteins; Antigens, Viral; Rotavirus; Protein Denaturation; Protein Domains; Circular Dichroism; Protein Folding; Escherichia coli; Humans; Recombinant Proteins
PubMed: 38592735
DOI: 10.1042/BSR20232178 -
Food Chemistry Aug 2024Edible insects represent a great alternative protein source but food neophobia remains the main barrier to consumption. However, the incorporation of insects as...
Influence of the processing on composition, protein structure and techno-functional properties of mealworm protein concentrates produced by isoelectric precipitation and ultrafiltration/diafiltration.
Edible insects represent a great alternative protein source but food neophobia remains the main barrier to consumption. However, the incorporation of insects as protein-rich ingredients, such as protein concentrates, could increase acceptance. In this study, two methods, isoelectric precipitation and ultrafiltration-diafiltration, were applied to produce mealworm protein concentrates, which were compared in terms of composition, protein structure and techno-functional properties. The results showed that the protein content of the isoelectric precipitation concentrate was higher than ultrafiltration-diafiltration (80 versus 72%) but ash (1.91 versus 3.82%) and soluble sugar (1.43 versus 8.22%) contents were lower. Moreover, the protein structure was affected by the processing method, where the ultrafiltration-diafiltration concentrate exhibited a higher surface hydrophobicity (493.5 versus 106.78 a.u) and a lower denaturation temperature (161.32 versus 181.44 °C). Finally, the ultrafiltration-diafiltration concentrate exhibited higher solubility (87 versus 41%) and emulsifying properties at pH 7 compared to the concentrate obtained by isoelectric precipitation.
Topics: Ultrafiltration; Animals; Hydrophobic and Hydrophilic Interactions; Insect Proteins; Tenebrio; Chemical Precipitation; Solubility; Hydrogen-Ion Concentration; Food Handling
PubMed: 38581785
DOI: 10.1016/j.foodchem.2024.139177 -
Food Chemistry: X Jun 2024This study explored the active food packaging application of phycocyanin- and Spirulina extract-loaded gliadin electrospun fibers (GPhy and GSPE). SEM findings confirmed...
This study explored the active food packaging application of phycocyanin- and Spirulina extract-loaded gliadin electrospun fibers (GPhy and GSPE). SEM findings confirmed that the morphology of fibers was tubular, showing the GPhy and GSPE as the optimum fibers. The loading efficiencies of GPhy and GSPE were also around 90%, which proved the well-incorporated compounds within the fibers. Simulation results of α-gliadin dissolved in acetic acid illustrated the denaturation of the protein. FTIR and TGA confirmed that after electrospinning the chemical/structural changes and enhanced thermostabilities occurred, respectively. Antibacterial and antioxidant tests detected higher bactericidal and antioxidative effects of GSPE than GPhy. In the application part, it was found that GPhy and GSPE were able to decrease PV and TBA values as the indications of walnut kernels' protection from lipid oxidation. This work shows a facile and an efficient way to fabricate active food packaging materials using electrospinning and natural compounds.
PubMed: 38571575
DOI: 10.1016/j.fochx.2024.101275 -
Acta Pharmaceutica (Zagreb, Croatia) Mar 2024This study aims to assess the chemical composition of the aqueous extract of L. leaves, as well as the potential of aqueous and hydroethanol extracts of the leaves and...
This study aims to assess the chemical composition of the aqueous extract of L. leaves, as well as the potential of aqueous and hydroethanol extracts of the leaves and seeds as analgesic, anti--inflammatory, and antioxidant agents. The contents of phenolics and inorganic constituents were determined in seeds and leaves; antioxidant capacity was assessed by 3 complementary and diverse tests. The carrageenan-induced paw edema technique was used to investigate the anti-inflammatory effect , and albumin denaturation to evaluate the anti-inflammatory effect . The acetic acid-induced contortion test, the tail-flick test, and the plantar test were used to assess the analgesic effi cacy . Chemical analysis was performed by UPLC-MS/MS to quantify several phenolic compounds including catechin (1,627.6 mg kg), quercitrin (1,235.8 mg kg-1) and gallic acid (628. 2 mg kg). The ICP analysis revealed that potassium and calcium were the main inorganic components in the seeds and leaves of . The hydroethanolic extract of the leaves showed the highest content of polyphenols/flavonoids, whereas the highest value of proantho cyanidins was detected in the aqueous extract of the seeds. All extracts showed potent antioxidant activity related to different phenolic compounds (quercetin, gallic acid, astragalin, catechin, and rutin). The aqueous extract of the leaves strongly inhibited paw edema (76.1 %) after 6 h of treatment and showed maximal inhibition of protein denaturation (191.0 µg mL for 50 % inhibition) and analgesic activity in different nociceptive models. The presented data reveal that extracts potentially show antioxidant, anti-inflammatory, and analgesic activities that could confirm the traditional use of this plant.
Topics: Antioxidants; Cistus; Chromatography, Liquid; Catechin; Plant Extracts; Pain; Tandem Mass Spectrometry; Analgesics; Anti-Inflammatory Agents; Phenols; Gallic Acid; Edema; Plant Leaves
PubMed: 38554388
DOI: 10.2478/acph-2024-0002 -
Food Chemistry: X Jun 2024This study aimed to utilize S-15 for the preparation of fermented shrimp gels. The gel properties and the gelation mechanism of proteins were investigated under...
This study aimed to utilize S-15 for the preparation of fermented shrimp gels. The gel properties and the gelation mechanism of proteins were investigated under acid-induced denaturation and protein degradation, and the quality of the gel was evaluated. Results showed that the pH of the shrimp surimi decreased from 7.35 to 4.74. The optimal gel strength observed at 24 h of fermentation was 326.41 g × cm, and disulfide bonds played a crucial role in the fermented gel. The fermented gel exhibited higher cooking loss rates and freeze-thaw loss rates compared to the heat-induced gel (control). However, fermented gels exhibited high overall acceptability both before and after cooking. The volatile basic nitrogen content in the fermented gel remained below 28.00 mg/100 g, within the safe range, and no histamine was detected. The results provide valuable data for the development and reprocessing of fermented shrimp surimi gel.
PubMed: 38550895
DOI: 10.1016/j.fochx.2024.101314 -
Vaccines Feb 2024COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a recurrent endemic disease affecting the whole world. Since November...
Vaccine Based on Recombinant Fusion Protein Combining Hepatitis B Virus PreS with SARS-CoV-2 Wild-Type- and Omicron-Derived Receptor Binding Domain Strongly Induces Omicron-Neutralizing Antibodies in a Murine Model.
BACKGROUND
COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a recurrent endemic disease affecting the whole world. Since November 2021, Omicron and its subvariants have dominated in the spread of the disease. In order to prevent severe courses of disease, vaccines are needed to boost and maintain antibody levels capable of neutralizing Omicron. Recently, we produced and characterized a SARS-CoV-2 vaccine based on a recombinant fusion protein consisting of hepatitis B virus (HBV)-derived PreS and two SARS-CoV-2 wild-type RBDs.
OBJECTIVES
To develop a PreS-RBD vaccine which induces high levels of Omicron-specific neutralizing antibodies.
METHODS
We designed, produced, characterized and compared strain-specific (wild-type: W-PreS-W; Omicron: O-PreS-O), bivalent (mix of W-PreS-W and O-PreS-O) and chimeric (i.e., W-PreS-O) SARS-CoV-2 protein subunit vaccines. Immunogens were characterized in vitro using protein chemical methods, mass spectrometry, and circular dichroism in combination with thermal denaturation and immunological methods. In addition, BALB/c mice were immunized with aluminum-hydroxide-adsorbed proteins and aluminum hydroxide alone (i.e., placebo) to study the specific antibody and cytokine responses, safety and Omicron neutralization.
RESULTS
Defined and pure immunogens could be produced in significant quantities as secreted and folded proteins in mammalian cells. The antibodies induced after vaccination with different doses of strain-specific, bivalent and chimeric PreS-RBD fusion proteins reacted with wild-type and Omicron RBD in a dose-dependent manner and resulted in a mixed Th1/Th2 immune response. Interestingly, the RBD-specific IgG levels induced with the different vaccines were comparable, but the W-PreS-O-induced virus neutralization titers against Omicron (median VNT50: 5000) were seven- and twofold higher than the W-PreS-W- and O-PreS-O-specific ones, respectively, and they were six-fold higher than those of the bivalent vaccine.
CONCLUSION
Among the tested immunogens, the chimeric PreS-RBD subunit vaccine, W-PreS-O, induced the highest neutralizing antibody titers against Omicron. Thus, W-PreS-O seems to be a highly promising COVID-19 vaccine candidate for further preclinical and clinical evaluation.
PubMed: 38543863
DOI: 10.3390/vaccines12030229 -
Pharmaceuticals (Basel, Switzerland) Mar 2024exhibits promising pharmacological activity, hinting at anti-inflammatory and anti-arthritic effects. This study investigated seed extracts from using methanol and...
Exploring the Therapeutic Potential of Seed Extracts: A Multi-Faceted Analysis of Phytochemical Composition, Anti-Inflammatory Efficacy, Predictive Anti-Arthritic Properties, and Molecular Docking Insights.
exhibits promising pharmacological activity, hinting at anti-inflammatory and anti-arthritic effects. This study investigated seed extracts from using methanol and n-hexane, focusing on anti-inflammatory and anti-arthritic properties. The methanol extract outperformed the n-hexane extract and diclofenac, a reference anti-inflammatory drug, in trypsin inhibition (85% vs. 30% and 64.67% at 125 μg/mL). For trypsin inhibition, the IC50 values were 82.97 μg/mL (methanol), 202.70 μg/mL (n-hexane), and 97.04 μg/mL (diclofenac). Additionally, the n-hexane extract surpassed the methanol extract and diclofenac in BSA (bovine serum albumin) denaturation inhibition (90.4% vs. 22.0% and 51.4% at 62.5 μg/mL). The BSA denaturation IC50 values were 14.30 μg/mL (n-hexane), 5408 μg/mL (methanol), and 42.30 μg/mL (diclofenac). Gas chromatography-mass spectrometry (GC-MS) revealed 59 and 58 secondary metabolites in the methanol and n-hexane extracts, respectively. The higher therapeutic activity of the methanol extract was attributed to hydroxyacetic acid hydrazide, absent in the n-hexane extract. In silico docking studies identified 28 compounds with negative binding energies, indicating potential trypsin inhibition. The 2-hydroxyacetohydrazide displayed superior inhibitory effects compared to diclofenac. Further mechanistic studies are crucial to validate 2-hydroxyacetohydrazide as a potential drug candidate for rheumatoid arthritis treatment.
PubMed: 38543170
DOI: 10.3390/ph17030385 -
Foods (Basel, Switzerland) Mar 2024To determine whether sarcoplasmic proteins affected water migration in myofibrils during air-drying, with protein denaturation as an indicator of sarcoplasmic protein...
To determine whether sarcoplasmic proteins affected water migration in myofibrils during air-drying, with protein denaturation as an indicator of sarcoplasmic protein changes, the extent of sarcoplasmic protein changes in lamb during air-drying was first studied. The results showed that sarcoplasmic protein's thermal stability decreased and secondary structure changed, indicating sarcoplasmic protein denatured in lamb during air-drying (35 °C, 60% RH, 3 m/s wind speed). Subsequently, the effect of sarcoplasmic protein solutions, dried at different times and rates, on myofibril protein-water interaction was studied in vitro. Two sets of sarcoplasmic protein solutions were dried for 0, 3, 6, and 9 h in a drying oven, resulting in different degrees of change. These two sets with higher or lower drying rates were achieved by controlling the contact area between sarcoplasmic protein solution and air. These dried sarcoplasmic protein solutions were then mixed with extracted myofibril and incubated for 2 h. The results showed a significant increase in T relaxation time of the incubation system when sarcoplasmic protein solution was dried at 35 °C for 3 h. This indicated that myofibrillar protein-water interaction was weakened, facilitating water migration from the inside to the outside of myofibrils. The denaturation degree of sarcoplasmic proteins was slowed by a higher drying rate, thereby alleviating the increase in the amount of immobile water within myofibrils when dried for 6 h. In conclusion, the properties of sarcoplasmic proteins were influenced by both drying rate and time, thereby influencing the water migration within myofibrils during air-drying.
PubMed: 38540920
DOI: 10.3390/foods13060930 -
Proceedings of the National Academy of... Apr 2024Trimethylamine-N-oxide (TMAO) and urea are metabolites that are used by some marine animals to maintain their cell volume in a saline environment. Urea is a well-known...
Trimethylamine-N-oxide (TMAO) and urea are metabolites that are used by some marine animals to maintain their cell volume in a saline environment. Urea is a well-known denaturant, and TMAO is a protective osmolyte that counteracts urea-induced protein denaturation. TMAO also has a general protein-protective effect, for example, it counters pressure-induced protein denaturation in deep-sea fish. These opposing effects on protein stability have been linked to the spatial relationship of TMAO, urea, and protein molecules. It is generally accepted that urea-induced denaturation proceeds through the accumulation of urea at the protein surface and their subsequent interaction. In contrast, it has been suggested that TMAO's protein-stabilizing effects stem from its exclusion from the protein surface, and its ability to deplete urea from protein surfaces; however, these spatial relationships are uncertain. We used neutron diffraction, coupled with structural refinement modeling, to study the spatial associations of TMAO and urea with the tripeptide derivative glycine-proline-glycinamide in aqueous urea, aqueous TMAO, and aqueous urea-TMAO (in the mole ratio 1:2 TMAO:urea). We found that TMAO depleted urea from the peptide's surface and that while TMAO was not excluded from the tripeptide's surface, strong atomic interactions between the peptide and TMAO were limited to hydrogen bond donating peptide groups. We found that the repartition of urea, by TMAO, was associated with preferential TMAO-urea bonding and enhanced urea-water hydrogen bonding, thereby anchoring urea in the bulk solution and depleting urea from the peptide surface.
Topics: Animals; Urea; Peptides; Water; Methylamines; Membrane Proteins
PubMed: 38536756
DOI: 10.1073/pnas.2317825121 -
Food Research International (Ottawa,... Apr 2024Drying is a necessary step in the microalgae production chain to reduce microbial load and oxidative degradation of the end product. Depending on the differences in...
Drying is a necessary step in the microalgae production chain to reduce microbial load and oxidative degradation of the end product. Depending on the differences in applied temperature and treatment time, the process of drying can have a substantial impact on protein quality and aroma, important characteristics determining the incorporation potential in food products. In this study, we compared the drying of heterotrophic Chorella vulgaris with both innovative (agitated thin film drying (ATFD), pulse combustion drying (PCD) and solar drying (SolD)) and commonly used drying techniques (spray drying (SprD) and freeze drying (FD)). To evaluate the impact on protein quality, we evaluated techno-functional properties, in vitro digestibility (INFOGEST) as well as protein denaturation using differential scanning calorimetry (DSC). A sensory analysis was performed by a trained expert panel, combined with headspace solid-phase microextraction (HS-SPME) - gas chromatography-mass spectrometry (GC-MS) to determine volatile organic compounds (VOCs). ATFD was found to increase techno-functional properties such as gelling, water holding and solubility as well as in vitro protein digestibility. These observations could be related to induced cell disruption and protein denaturation by ATFD. Sensory analysis indicated an increased earthy off-flavor after ATFD. Interestingly, the high-temperature PCD led to an increase in cacao odor while low-temperature FD resulted in lower flavor, odors and VOCs. These results demonstrate that protein quality and sensorial properties of C. vulgaris can be steered through the type of drying, which could help in the selection of application-specific drying methods. Overall, this work could promote the incorporation of microalgal single cell proteins in different innovative food products.
Topics: Chlorella vulgaris; Desiccation; Freeze Drying; Gas Chromatography-Mass Spectrometry; Odorants; Volatile Organic Compounds; Microalgae
PubMed: 38519160
DOI: 10.1016/j.foodres.2024.114142