In this study, label-free quantitative proteomics was used to investigate the biological functions of M. oleifera seed proteins, which resulted in the identification of milk-clotting proteases. In ...total, 921 proteins were identified, and proteins within the molecular weight range of 30–50 kDa were abundant. The identified proteins were mainly involved in catalytic activity and metabolic processes associated with carbohydrate and protein metabolism, among which, proteases in the observed molecular weight range could possibly be responsible for the previously reported milk-clotting activity. An aspartic-type endopeptidase with molecular mass of 45,517 Da was purified from M. oleifera seeds using ammonium sulfate precipitation, ultrafiltration, and preparative high performance liquid chromatography, and was characterized using liquid chromatography-mass spectrometry (LC-MS)/MS. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the purified protease exhibited hydrolase activity and was involved in several metabolic pathways, which further confirmed that proteomic analysis can assist in the purification of the milk-clotting protease. The optimal temperature and pH required for protease activity were 60 °C and 5.0, respectively. The high thermal stability and good pH stability of the protease indicated that it can be used in the dairy industry.
•Proteomics was used to investigate the biological functions of M. oleifera seeds.•Proteases of 30–50 kDa were possibly responsible for the milk-clotting activity.•An aspartic-type endopeptidase with molecular mass of 45,517 Da was purified.•Proteomic analysis can assist in the purification of the milk-clotting protease.•The protease exhibited high thermal stability and good pH stability.
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•A facile and scalable strategy is developed to synthesize a new cathode material.•A thin layer of polypyrrole is coated on the surface of MnO2/Mn2O3 nanocomposite.•The polypyrrole ...coating can effectively alleviate the dissolution of Mn2+ ions.•The product shows significantly improved electrochemical performances.•The electrochemical kinetics and stability are considerably enhanced.
Rechargeable aqueous zinc-ion batteries based on Mn-based cathode materials are of considerable interest for large-scale energy storage. However, the intrinsic low electronic conductivity and the dissolution issue of Mn-based cathode materials result in slow reaction kinetics and fast capacity fading. Herein, a facile and scalable strategy combining molten salt synthesis and self-initiated polymerization is developed to in-situ generate a thin layer of polypyrrole onto the surface of MnO2/Mn2O3 nanocomposite, aiming to resolve the problems mentioned above. The obtained product provides large specific capacity (289.8 mAh g−1 at 0.2 A g−1), remarkable rate capability (199.8 mAh g−1 at 3 A g−1), and excellent cycling stability (96.7% after 1000 cycles at 1 A g−1, compared to the 2nd cycle). The cyclability remains good when Mn2+ ions are not pre-added into the electrolyte. Also, the obtained product exhibits slight electrochemical polarization, low charge transfer impedance after cycling, high capacitive contribution, and large electrolyte ion diffusion coefficient. All these performances and properties are significantly superior to that of MnO2/Mn2O3 nanocomposite without polypyrrole coating. This work opens a new path towards long-life and fast-discharging electrode materials.
Binglangjiang buffalo is a new type of river buffalo discovered in Tengchong of Yunnan Province, China, with rich protein in milk. In this study, we isolated novel α-glucosidase inhibitory peptides ...from the buffalo casein hydrolyzed by Dregea sinensis protease using RP-HPLC. A total of 26 peptides in the active fraction were identified by LC-MS/MS, mainly belonging to αs1-CN, αs2-CN, and β-CN. Based on bioinformatics analysis, four peptides with potential α-glucosidase inhibitory activity were selected for chemical synthesis and activity verification. The four synthetic peptides exhibited α-glucosidase inhibitory activity and had IC50s of 470.492 ± 3.086 μmol/L (P3), 498.040 ± 1.829 μmol/L (P2), 503.635 ± 3.269 μmol/L (P1), and 542.502 ± 1.995 μmol/L (P4). Through molecular docking, we found that these four peptides may occupy the potential catalytic active sites (Arg387, Arg428, Arg727, Arg801, Arg799, and Trp710) of α-glucosidase through forming hydrogen bonds and hydrophobicity, thus hindering the formation of complex and glycosylation between α-glucosidase and substrate. Screening α-glucosidase from buffalo casein hydrolysates will provide insights for further study on the antidiabetic mechanism of the peptides and further development of antidiabetic functional food.
•Buffalo casein hydrolyzed by novel protease showed α-glucosidase inhibition.•Four peptides were synthesized and validated based on bioinformatics analysis.•The four peptides isolated from αS1, αS2-CN exhibited potent α-glucosidase inhibition.•The interaction between peptides and α-glucosidase was analyzed by molecular docking.
A facile, scalable, and cost-effective molten salt method is developed to synthesize α-MnO2/Mn2O3 nanocomposite, which exhibits great electrochemical performances as the cathode material for aqueous ...zinc-ion batteries.
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Thanks to low cost, high safety, and large energy density, aqueous zinc-ion batteries have attracted tremendous interest worldwide. However, it remains a challenge to develop high-performance cathode materials with an appropriate method that is easy to realize massive production. Herein, we use a molten salt method to synthesize nanostructured manganese oxides. The crystalline phases of the manganese oxides can be tuned by changing the amount of reduced graphene oxide added to the reactant mixture. It is found that the α-MnO2/Mn2O3 nanocomposite with the largest mass ratio of Mn2O3 delivers the best electrochemical performances among all the products. And its rate capability and cyclability can be significantly improved by modifying the Zn anode with carbon black coating and nanocellulose binder. In this situation, the nanocomposite can deliver high discharging capacities of 322.1 and 213.6 mAh g−1 at 0.2 and 3 A g−1, respectively. After 1000 cycles, it can retain 86.2% of the capacity at the 2nd cycle. Thus, this nanocomposite holds great promise for practical applications.
Conjugated linoleic acid (CLA) is an unsaturated fatty acid with many active functions. Here, we demonstrate quorum sensing (QS) to study mechanisms involved in CLA production of L. fermentum L1. ...Addition of linoleic acid (LA) with increased concentration results in promising CLA production of 2.22–10.36 mg/mL, cell density and autoinducer-2 (AI-2) involved in QS of L1. Further, proteomics analysis quantified up-expression of 185 differentially expressed proteins (DEPs) upon addition substrate of 8% LA, including myosin cross-reactive antigen protein, enolase (eno), and S-ribosylhomocysteine lyase (luxS), while 174 DEPs were down-regulated. Furthermore, S-Adenosyl-l-methionine metabolic pathway involved in luxS/AI-2 QS system was up-regulated. Additionally, protein-protein interaction network leverage key proteins, luxS and eno responsible for CLA production. Finally, furanone inhibitor block luxS/AI-2 QS system to allow AI-2 content, CLA, and cell density of L1 to decrease level. Western blot analysis confirmed, furanone successfully inhibited expression of luxS and eno. Whereas, luxS/AI-2 QS system was activated with LA results in increase expression of eno and production of CLA. Collectively, this study provides a new mechanism of CLA production by lactic acid bacteria.
Milk fan cheese, a type of stretched -cheese, presents challenges in its stretch-forming. This study investigated the impacts of complex phosphates (sodium tripolyphosphate and sodium dihydrogen ...phosphate, STPP-DSP) on the gelling properties of acid-induced milk fan gel and the mechanisms contributing to its stretch-forming. The treatment of milk fan gel with STPP-DSP resulted in improved functional and textural properties compared with the control group. In particular, drawing length increased significantly from 69.67 nm to 80.33 nm, and adhesiveness increased from 1737.89 g/mm to 1969.79 g/mm. The addition of STPP-DSP also led to increased viscosity, elastic modulus (G'), and viscous modulus (G”). Microstructural analysis revealed the formation of a fibrous structure within the gel after STPP-DSP treatment, facilitating uniform embedding of fat globules and emulsification. Structural analysis showed that the addition of STPP-DSP increased β-fold and decreased random coiling of the gel, facilitating the unfolding of protein structures. Additionally, UV absorption spectroscopy and excitation-emission matrix spectroscopy results indicated the formation of a chelate between STPP-DSP and milk fan gel, increasing protein-protein molecular interactions. Evidence from differential scanning calorimetry and x-ray diffraction demonstrated the formation of sodium caseinate chelate. Fourier transform infrared spectroscopy and zeta potential analysis revealed that the sodium caseinate chelate formed through hydrophobicity, hydrogen bonding, and electrostatic forces. These findings provided theoretical insights into how phosphates can improve the stretch-forming of milk fan gel, facilitating the application of phosphate additives in stretched -cheese processing.
In this paper, a new method for deriving the moving least-squares (MLS) approximation is presented first. Considering the unclear physical meaning of the functional in the existing complex variable ...moving least-squares (CVMLS) approximation, an improved CVMLS approximation is presented by constructing a new functional with an explicit physical meaning. Based on the improved CVMLS approximation, the complex variable interpolating moving least-squares (CVIMLS) method is presented, and the interpolating property of the corresponding shape function of the CVIMLS method is proved.
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•The impact of genetic background on the peptide profiles of hams was evaluated.•44 and 29 specific peptides of Dahe black pig and hybrid pig hams were discovered.•Specific peptides ...were primarily hydrolysed from myosin, myoglobin and troponin-T.•Antioxidant activity of peptide from Dahe black pigs ham was significantly higher.•Dahe black ham derived specific antioxidant peptide AR14 was screened and evaluated.
The quality of hams obtained from different pig breeds can vary depending on endogenous antioxidant peptides in the hams. The aims of this study were (i) to investigate the specific peptides in Chinese Dahe black pig ham (DWH) and hybrid pig ham (Yorkshire × Landrace × Dahe black ham, YLDWH) and their antioxidant activity, and (ii) to elucidate the relationship between ham quality and antioxidant peptides. iTRAQ quantitative peptidomic method was used to discover specific peptides of DWH and YLDWH. In addition, in vitro assays were performed to evaluate their antioxidant activity. A total of 73 specific peptides were identified from DWH and YLDWH by LC-MS/MS. Forty-four specific peptides in DWH were primarily hydrolysed from myosin and myoglobin by endopeptidases, while 29 specific peptides in YLDWH were primarily hydrolysed from myosin and troponin-T. Six specific peptides that were statistically significantly different based on their fold changes and P-values were selected for the identification of DWH and YLDWH. DWH-derived specific peptide AGAPDERGPGPAAR (AR14), which had high stability and was non-toxic, had the highest DPPH• and ABTS•+ scavenging activity (IC50 = 1.657 mg/mL and 0.173 mg/mL, respectively) and cellular antioxidant capacity. Molecular docking showed that AR14 interacted with Val369, and Val420 of Keap1 via hydrogen bonds. Furthermore, AR14 bound to DPPH and ABTS through hydrogen bonding and hydrophobic interactions. Together, our results demonstrate that the DWH-derived antioxidant peptide AR14 exhibits the free radical scavenging and cellular antioxidant activity and can be used to preserve ham quality and promote human health.
Aims
Staphylococcus aureus has emerged as a serious threat to food safety owing to biofilm formation. The study aimed to examine the antibiofilm mechanism of a novel milk‐derived antimicrobial ...peptide BCp12 against it.
Methods and results
Antibiofilm activity of BCp12 was studied by crystal violet staining, MTT assay, motility, SEM and CLSM. TMT proteome, real‐time PCR and molecular docking in silico were conducted to evaluate the mechanism of BCp12 against S. aureus biofilm. The results showed that BCp12 had significant antibiofilm activity at 1 × MIC and sub‐MIC. BCp12 induced the dispersion of structure of S. aureus biofilm BCp12 inhibited the movement of S. aureus. A total of 703 proteins were downregulated and 334 proteins were upregulated after BCp12 treatment. The proteins (agrA, agrB, agrC and psmβ) of the QS systems were downregulated. Additionally, the expression of the agr‐related genes, agrA, agrB, agrC and psmβ, was downregulated. BCp12 was bound to the receptor proteins agrA and agrC through hydrogen bonds and π–π bonds.
Conclusions
The results showed the antibiofilm activity of BCp12 and it inhibits the biofilm formation by interfering agr QS system.
Significance and Impact of Study
BCp12 has the potential to be a novel antibiofilm agent against S. aureus biofilm and used in the food industry.
Exopolysaccharides (EPS) produced by lactic acid bacteria considerably affect the texture of yogurt. However, the mechanism underlying the improvement in texture is not well understood. In this ...study, the structure-activity relationship of the neutral polysaccharide, EPS-1, produced by Limosilactobacillus fermentum A51 (L. fermentum A51), and the mechanism underlying the formation of high-quality yogurt texture were investigated. The results showed that EPS-1 effectively filled the three-dimensional network structure of the casein (CAS) clusters and improved the textural properties of yogurt. Structural analysis demonstrated that EPS-1 was composed of fucose, galactose, glucose, mannose, and galacturonic acid. In addition, EPS-1 exhibited a crystalline structure (2θ = 19.98°) and possessed good thermal stability (223.8 °C) and gelling properties. Furthermore, porous and regular sheet-like structures were observed in the microstructure of EPS-1 using scanning electron microscopy (SEM). Moreover, X-ray diffraction, SEM, confocal laser scanning microscopy (CLSM), and particle size analysis confirmed the unique structure-activity relationship of EPS-1, which interacted with CAS clusters to form stable CAS-EPS-1 complexes. Fourier transform infrared spectroscopy and zeta potential analysis demonstrated that the complexes were formed via hydrogen bonding (N-H and O-H) and electrostatic interactions (amide bond). Molecular docking revealed that EPS-1 was bound to active residues, Ile27, Ser30, Glu20, Glu26, Val23, and Leu21, of α-CAS via hydrogen bonds. These findings offer new insights regarding how EPS improves the texture of yogurt and indicate that L. fermentum A51 can be used for improving the textural properties of dairy products.
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•Exopolysaccharide-1 (EPS-1) produced by L. fermentum A51 was characterized.•EPS-1 had good thermostability, crystalline structure, and gelling properties.•EPS-1 interacted with casein (CAS) clusters and improved the texture of yogurt.•FTIR, XRD, CLSM, and SEM analyses confirmed the formation of EPS-1-CAS complexes.•Hydrogen bonding (N-H and O-H) and electrostatic interactions were the driving forces.
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