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Foods (Basel, Switzerland) Sep 2023Spice and its extracts have gained widespread utilization as natural and eco-friendly additives, imparting enhancements in flavor, color, and antioxidative attributes to...
Spice and its extracts have gained widespread utilization as natural and eco-friendly additives, imparting enhancements in flavor, color, and antioxidative attributes to meat-based products. This work aims to study the effect mechanism of capsaicin (CA) and dihydrocapsaicin (DI) in capsicum (chili pepper) on the structure and function of myofibrillar proteins (MPs) in duck meat during thermal treatment. The results showed that at a CA-DI to MP ratio of 1:500 (g/g) following a 12 min heat treatment, the carbonyl content of MPs in duck meat decreased by 48.30%, and the sulfhydryl content increased by 53.42%. When the concentration was 1:500 (CA-DI, g/g) after 24 min of heat treatment, the •OH and DPPH radical scavenging rates were highest at 59.5% and 94.0%, respectively. And the initial denaturation temperature of MPs was the highest at 96.62 °C, and the thermal absorption was lowest at 200.24 J g. At the parameter, the smallest particle size and size distribution range of MP were 190 nm (9.51%). Furthermore, the interplay between CA-DI and MPs contributed to a reduction in the protein particle size and intrinsic fluorescence. In summary, the combination of CA-DI and MPs played a crucial role in inducing protein unfolding and disintegration.
PubMed: 37835186
DOI: 10.3390/foods12193532 -
Nature Methods Mar 2024Protein-protein interactions (PPIs) drive cellular processes and responses to environmental cues, reflecting the cellular state. Here we develop Tapioca, an ensemble...
Protein-protein interactions (PPIs) drive cellular processes and responses to environmental cues, reflecting the cellular state. Here we develop Tapioca, an ensemble machine learning framework for studying global PPIs in dynamic contexts. Tapioca predicts de novo interactions by integrating mass spectrometry interactome data from thermal/ion denaturation or cofractionation workflows with protein properties and tissue-specific functional networks. Focusing on the thermal proximity coaggregation method, we improved the experimental workflow. Finely tuned thermal denaturation afforded increased throughput, while cell lysis optimization enhanced protein detection from different subcellular compartments. The Tapioca workflow was next leveraged to investigate viral infection dynamics. Temporal PPIs were characterized during the reactivation from latency of the oncogenic Kaposi's sarcoma-associated herpesvirus. Together with functional assays, NUCKS was identified as a proviral hub protein, and a broader role was uncovered by integrating PPI networks from alpha- and betaherpesvirus infections. Altogether, Tapioca provides a web-accessible platform for predicting PPIs in dynamic contexts.
Topics: Sarcoma, Kaposi; Viral Proteins; Manihot; Virus Latency; Herpesvirus 8, Human
PubMed: 38361019
DOI: 10.1038/s41592-024-02179-9 -
Food Science & Nutrition Sep 2023The relative cryoprotective effects of flaxseed protein hydrolysate and pectin in comparison with conventional cryoprotectant (sucrose + sorbitol + sodium...
The relative cryoprotective effects of flaxseed protein hydrolysate and pectin in comparison with conventional cryoprotectant (sucrose + sorbitol + sodium tripolyphosphates) on stabilization of proteins in surimi of Capoor () were investigated during freezing (-20°C for 4 months) and chilling storage (4°C for 10 days). Although pectin caused to improve water-holding capacity (27.8%; 4°C and 21.5%; -20°C) on account of highly more inhibitory impact on the ice crystals growth, the protein denaturation may have occurred. It can be related to higher reduction in the amount of salt extractable protein (%) and the immeasurable value of thiol group in surimi formulation containing pectin compared with other cryoprotectants. The results of modeling surimi samples showed that salt extractable protein and sulfhydryl content were in good agreement with the first-order reaction model at -20°C and second-order kinetic model at 4°C. In comparison with other samples, samples treated with flaxseed protein showed the lowest reaction rate constant during chilled and frozen storage. The results confirmed that flaxseed protein with no sweetness and considerable caloric value had a cryoprotective effect similar to sucrose + sorbitol + polyphosphate and even better.
PubMed: 37701217
DOI: 10.1002/fsn3.3510 -
Journal of Biological Inorganic... Dec 2023Circular permutation (CP) is a technique by which the primary sequence of a protein is rearranged to create new termini. The connectivity of the protein is altered but...
Circular permutation (CP) is a technique by which the primary sequence of a protein is rearranged to create new termini. The connectivity of the protein is altered but the overall protein structure generally remains unperturbed. Understanding the effect of CP can help design robust proteins for numerous applications such as in genetic engineering, optoelectronics, and improving catalytic activity. Studies on different protein topologies showed that CP usually affects protein stability as well as unfolding rates. Though a significant number of proteins contain metals or other cofactors, reports of metalloprotein CPs are rare. Thus, we chose a bacterial metalloprotein, azurin, and its CP within the metal-binding site (cpF114). We studied the stabilities, folding, and unfolding rates of apo- and Zn-bound CP azurin using fluorescence and circular dichroism. The introduced CP had destabilizing effects on the protein. Also, the folding of the Zn-CP protein was much slower than that of the Zn-WT or apo-protein. We compared this study to our previously reported azurin-cpN42, where we had observed an equilibrium and kinetic intermediate. cpF114 exhibits an apparent two-state equilibrium unfolding but has an off-pathway kinetic intermediate. Our study hinted at CP as a method to modify the energy landscape of proteins to alter their folding pathways. WT azurin, being a faster folder, may have evolved to optimize the folding rate of metal-bound protein compared to its CPs, albeit all of them have the same structure and function. Our study underscores that protein sequence and protein termini positions are crucial for metalloproteins. TOC Figure. (Top) Zn-azurin WT structure (PDB code: 1E67) and 2-D topology diagram of Zn-cpF114 azurin. (Bottom) Cartoon diagram representing folding (red arrows) and unfolding (blue arrows) of apo- and Zn- WT and cpF114 azurins. The width of the arrows represents the rate of the corresponding processes.
Topics: Azurin; Protein Folding; Catalytic Domain; Apoproteins; Metals; Circular Dichroism; Kinetics
PubMed: 37957357
DOI: 10.1007/s00775-023-02023-z -
Food Chemistry Jul 2023This study aimed to find the specific relationship between quality traits and myofibrillar proteins (MPs) alteration of salted fish during frozen storage. Protein...
This study aimed to find the specific relationship between quality traits and myofibrillar proteins (MPs) alteration of salted fish during frozen storage. Protein denaturation and oxidation occurred in frozen fillets, with the denaturation occurring before oxidation. In the pre-phase of storage (0-12 weeks), protein structural changes (secondary structure and surface hydrophobicity) were closely related to the water-holding capacity (WHC) and textural properties of fillets. The MPs oxidation (sulfhydryl loss, carbonyl and Schiff base formation) were dominated and associated with changes in pH, color, WHC, and textural properties during the later stage of frozen storage (12-24 weeks). Besides, the brining at 0.5 M improved the WHC of fillets with less undesirable changes in MPs and quality traits compared to other concentrations. The 12 weeks was an advisable storage time for salted frozen fish and our results might provide an available suggestion for fish preservation in aquatic industry.
Topics: Animals; Carps; Protein Denaturation; Cyprinidae; Freezing; Proteins; Sodium Chloride
PubMed: 36808024
DOI: 10.1016/j.foodchem.2023.135714 -
Bioinformation 2023It is of interest to develop potent and safer anti-inflammatory drugs from plants, as medicinal plants and herbs attained great attention in the medical world due to...
It is of interest to develop potent and safer anti-inflammatory drugs from plants, as medicinal plants and herbs attained great attention in the medical world due to their multifunctional activities. This article studied the anti-inflammatory effects of lauric acid (LA), thiocolchicoside (TC) and thiocolchicoside-lauric acid (TC-LA) formulation. The anti-inflammatory effects of these compounds were determined by following the methods of inhibition of protein denaturation and proteinase inhibition activity. This was assessed at different concentrations to determine the 50% inhibition concentration (IC50) of the compounds. The result indicated that the activity of LA, TC, TC-LA formulation, and reference drug increased with the increase in the concentration from 10-50 µg/ml, thus proving the activity of LA, TC, and TC-LA formulation against inflammation was in a dose-dependent manner. The percentage of inhibition of protein denaturation was 59.56%, 66.94%, 86.62%, and 60.34% for LA, TC, the combination of TC-LA and standard drug, and the IC50 values were found to be 44.78 µg/mL, 37.65 µg/mL, 27.15 µg/mL and 43.42 µg/mL, respectively. The percentage of proteinase inhibition activity of LA, TC, and a combination of TC-LA and the standard drug was 66.65%, 77.49%, 94.07%, and 69.83%, and IC50 of LA, TC, a combination of TC-LA and standard drug were35.5 µg/mL, 32.12 µg/mL, 24.35 µg/mL and 37.80 µg/mL, respectively. We found out that lauric acid, thiocolchicoside, and thiocolchicoside-lauric acid formulation exhibited significant anti-inflammatory activity.
PubMed: 38046516
DOI: 10.6026/973206300191075 -
Food Chemistry May 2024When subjected to dry-heating, egg white ovalbumin, a phosphoglycoprotein, undergoes fragmentation and forms soluble aggregates. We investigated the mechanisms of...
When subjected to dry-heating, egg white ovalbumin, a phosphoglycoprotein, undergoes fragmentation and forms soluble aggregates. We investigated the mechanisms of dry-heat-induced fragmentation of ovalbumin. SDS-PAGE analysis showed that ovalbumin fragmented into five polypeptides, and their amount increased over 6 h of dry-heat treatment at 120 °C. The fragments contained fewer or no phosphoserine, compared with that in crude ovalbumin. Liquid chromatography-tandem mass spectrometry analysis of tryptic digests revealed that the fragmentation sites were located on phosphoserine residues, S and S. During fragmentation, the phosphoserine residues underwent conversion into dehydroalanine residues, which were subsequently hydrolyzed. The nitrogen from the dehydroalanine became a newly formed terminal amide group on the N-terminal fragment, while the remaining molecule predominantly formed a new terminal pyruvoyl group. Furthermore, the fragments were incorporated into monomers or soluble aggregates of ovalbumin via covalent and non-covalent bonds. This study demonstrated a novel mechanism for dry-heat-induced fragmentation of phosphoproteins.
Topics: Ovalbumin; Phosphoserine; Hot Temperature; Peptides; Egg White
PubMed: 38159316
DOI: 10.1016/j.foodchem.2023.138263 -
Current Research in Food Science 2023As a novel protein resource, the low digestibility of protein (SPP) limits its large-scale application. From the perspective of food processing methods, different...
As a novel protein resource, the low digestibility of protein (SPP) limits its large-scale application. From the perspective of food processing methods, different heating treatments were explored to improve the structure and digestibility of SPP. In this study, SPP was heated by water bath and microwave at the same heating rate and heating temperature. Microwave accelerated protein denaturation and structure unfolded as the heating intensity increases, causing more exposed hydrophobic residues and enhancing surface hydrophobicity. The data of free sulfhydryl group, particle size, and gel electrophoresis, showed that microwave treatment promoted the formation of protein aggregates. The structural changes can potentially improve the accessibility of digestive enzymes, promote the in vitro digestibility rate, and further accelerate the production of small molecular peptides and the release of free amino acids. This study provided an innovative approach to improve the digestibility and therefore the utilization efficiency of SPP.
PubMed: 37691697
DOI: 10.1016/j.crfs.2023.100581 -
Biochemical and Biophysical Research... Feb 2024Exosomes are small extracellular vesicles (EVs) found in culture supernatants, blood, and breast milk. The size of these nanocomplexes limits the methods of EV analyses....
Exosomes are small extracellular vesicles (EVs) found in culture supernatants, blood, and breast milk. The size of these nanocomplexes limits the methods of EV analyses. In this study, nitrobenzoxadiazole (NBD), a fluorophore, conjugated endosome-lysosome imager, GIF-2250 and its derivative, GIF-2276, were evaluated for exosome analyses. A correlation was established between GIF-2250 intensity and protein maker levels in bovine milk exosomes. We found that high-temperature sterilization milk may not contain intact exosomes. For precise analysis, we synthesized GIF-2276, which allows for the covalent attachment of NBD to the Lys residue of exosome proteins, and labeled milk exosomes were separated using a gel filtration system. GIF-2276 showed chromatographic peaks of milk exosomes containing >3 ng protein. The area (quantity) and retention time (size) of the exosome peaks were correlated to biological activity (NO synthesis suppression in RAW264.7 murine macrophages). Heat denaturation of purified milk-derived exosomes disrupted these indicators. Proteome analyses revealed GIF-2276-labeled immunomodulators, such as butyrophilin subfamily 1 member A1 and polymeric immunoglobulin receptor. The immunogenicity and quantity of these factors decreased by heat denaturation. When milk exosomes were purified from market-sourced milk we found that raw and low-temperature sterilization milk samples, contained exosomes (none in high-temperature sterilization milk). These results were also supported by transmission electron microscopy analyses. We also found that GIF-2276 could monitor exosome transportation into HEK293 cells. These results suggested that GIF-2250/2276 may be helpful to evaluate milk exosomes.
Topics: Female; Humans; Mice; Animals; Milk; Exosomes; HEK293 Cells; Milk, Human; Extracellular Vesicles; Proteome
PubMed: 38219490
DOI: 10.1016/j.bbrc.2024.149505 -
Foods (Basel, Switzerland) Jul 2023The kinetic properties and thermal characteristics of fresh pork meat proteins (), as well as osmotically dehydrated meat proteins, were investigated using differential...
The kinetic properties and thermal characteristics of fresh pork meat proteins (), as well as osmotically dehydrated meat proteins, were investigated using differential scanning calorimetry. Two isoconversional kinetical methods, namely the differential Friedman and integral Ortega methods, were employed to analyze the data. The obtained kinetic triplet, activation energy, pre-exponential factor, and extent of conversion, has been discussed. The resulting activation energy for proteins of fresh meat ranges between 751 kJ·mol for myosin, 152 kJ·mol for collagen and sarcoplasmic proteins, and 331 kJ·mol for actin at a conversion degree of 0.1 to 0.9. For osmotically dried pork meat proteins, the values range from 307 kJ·mol for myosin 272 kJ·mol for collagen and sarcoplasmic proteins, and 334.83 kJ·mol for actin at a conversion degree from 0.1 to 0.9. The proteins of the dry meat obtained by osmotic dehydration in molasses could be described as partly unfolded as they retain the characteristic protein denaturation transition. Concerning the decrease in enthalpies of proteins denaturation, thermodynamic destabilization of dried meat proteins occurred. On the contrary, dried meat proteins were thermally stabilized with respect to increase in the temperatures of denaturation. Knowledge of the nature of meat protein denaturation of each kind of meat product is one of the necessary tools for developing the technology of meat product processing and to achieve desired quality and nutritional value. The kinetic analysis of meat protein denaturation is appropriate because protein denaturation gives rise to changes in meat texture during processing and directly affects the quality of product.
PubMed: 37569136
DOI: 10.3390/foods12152867