Search Results (881)

Ice recrystallization inhibition (IRI) activity of peptides is influenced by both peptide length and secondary structure; however, whether combinations of peptides with different lengths exhibit cooperative or antagonistic effects remains poorly understood. Using molecular dynamics simulations, this study investigated how secondary structure and chain-length heterogeneity jointly affect the IRI activity of peptide-pair mixtures. For systems containing only β-sheet-rich peptides, mixtures of different chain lengths consistently reduced ice content relative to the corresponding single-peptide systems, suggesting cooperative enhancement of IRI activity. In contrast, individual α-helical peptides showed strong inhibition of ice growth, but this effect was diminished after they were mixed into peptide pairs. Structural analyses suggested that the improved performance of β-sheet mixtures was associated less with the simple preservation of native β-sheet structure than with mixing-induced changes in peptide–peptide coupling and surface exposure. By contrast, helix-containing mixtures retained more of their original local structure in some cases, but this structural retention was not accompanied by improved ice-growth suppression after mixing. Together, these findings suggest that peptide length effects on IRI are not universally synergistic but depend strongly on secondary-structure compatibility. Full article

Northern pike (Esox lucius) myofibrillar protein (MP) forms inherently weak gels due to endogenous proteolytic activity and the low thermal stability of fish myosin, limiting its application in surimi products. This study investigated the reinforcing effect and underlying mechanism of rice protein amyloid fibrils (RFs) on pike MP gels. Dynamic rheology revealed that RFs increased both the storage and loss moduli in a concentration-dependent manner, with the 5% group exhibiting an approximately threefold increase in the G′ at 100 rad/s relative to the control. The gel strength, hardness, and chewiness increased progressively with the RF content, whereas the water-holding capacity peaked at 1–3% RFs and declined sharply at 5% RFs. Microstructural imaging showed that moderate RF levels promoted a dense, homogeneous network architecture, while excessive RFs induced phase separation and structural heterogeneity. Hydrophobic interactions and hydrogen bonds were strengthened via RF incorporation, while disulfide bonds decreased monotonically with the increasing fibril concentration. FTIR spectroscopy revealed an α-helix-to-β-sheet transition, with the β-sheet content reaching a maximum of 49.37% at 3% RFs, and SDS-PAGE confirmed that the RF–MP interactions were predominantly non-covalent in nature. These results demonstrate that RFs reinforce pike MP gels through a molecular mechanism involving rigid fibrils acting as structural scaffolds within the protein network and a progressive shift from disulfide-mediated covalent crosslinking toward non-covalent stabilization via hydrophobic interactions and hydrogen bonding. The 1–3% RF range delivers the most balanced gel properties, while excessive fibril loading at 5% induces over-aggregation and impairs water retention. These findings establish amyloid fibrils as effective structural modifiers for freshwater fish gel products and provide a mechanistic basis for their application in surimi processing. Full article

Peanut protein (PP) is an abundant plant protein resource with limited gelation performance. In this study, the effects of co-precipitation with egg white protein (EWP) on the structural and gelation properties of PP were investigated. Structural analysis revealed that co-precipitation induced secondary structure rearrangement of PP, accompanied by decreased α-helix and β-sheet contents and increased random coil and β-turn contents. These changes were associated with the exposure of hydrophilic groups and the partial shielding of hydrophobic regions, contributing to the significantly improved solubility of PP-EWP co-precipitated proteins (p < 0.05). These structural changes were conducive to the formation of a denser and more continuous gel network. Compared with the PP gel, the gel prepared from PP-EWP co-precipitated protein at the PP:EWP ratio of 2:1 showed an increase in gel strength from 429.30 g to 911.94 g and in water holding capacity from 56.78% to 85.53%. This study provides a theoretical basis and practical guidance for improving the gel properties of PP through co-precipitation and developing functional peanut protein ingredients, although the relatively high cost of EWP should be considered in practical applications. Full article

Senecavirus A (SVA) is a newly emerging picornavirus associated with porcine idiopathic vesicular disease and sudden death in newborn piglets. Currently, no specific vaccines or drugs are available against SVA, highlighting the importance of investigating the immunological characteristics of its key proteins. The VP1 protein of SVA exhibits strong immunogenicity and high sequence conservation, and it is indispensable to the viral life cycle. In the present study, a monoclonal antibody (mAb) against VP1 was generated. A series of truncated VP1 proteins was then expressed to precisely map the epitope recognized by this mAb. The minimal reactive unit was identified as ¹⁶DTDFSGELA²⁴. Homology analysis further revealed that this epitope is conserved among different SVA isolates deposited in GenBank. Moreover, AlphaFold prediction, along with PyMOL (Version 3.0.3) and GETAREA analyses, reveals that this epitope resides in the α-helix and loop regions of the three-dimensional structure of the VP1 protein and is surface-exposed. Collectively, these findings indicate that the mAb and its recognized epitope represent valuable tools for investigating SVA etiology and VP1 protein function. Full article

This study added two types of resistant dextrin (RD), i.e., Bailong (BL) and Luo Gaite (LGT)) to a Japonica (cv. RXY) and an early indica (cv. IP44) rice during cooking and analysed the functional and structural properties of the cooked rice. Compared with no RD addition, 3–10% RD addition induced a declinein cooking time and an incrementin gruel solid loss. Further, 3–10% RD addition increased the hardness, chewiness, and springiness of cooked rice but decreased the cohesiveness. With increases in the added RD amount, the smell, structural appearance, palatability, taste, cool rice texture, and total score of the cooked rice all increased; the peak time and pasting temperature increased, but the peak, final, breakdown, and setback viscosities all significantly decreased. The enthalpy, conclusion temperature of gelatinisation, and gelatinisation peak width and height all decreased with increasing RD amount, but the peak temperature of gelatinisation increased. The addition of 3–7% RD did not change amylopectin ageing, but 10% RD significantly increased amylopectin ageing. RD addition reduced the protein weakness degree and starch breakdown torque of rice doughbut appeared to increase the amorphous and crystalline regions of cooked rice. The addition of 10% BL or LGT induced the formation of α-helix and random coil secondary protein structures in cooked rice, with optimal cooking properties and total sensory score. Microstructure analysis further showed that low-viscous RD induced the formation of new gel-like structures. In conclusion, 3–10% RD addition in cooking rice decreases amylose recrystallisation, weakens the protein structure, and induces new gel-like structures, enhancing the hardness, chewiness, adhesiveness, springiness, and sensory score of cooked rice. This study is useful for developing functionalcooked rice. Full article

Porcine blood meal-derived hydrolysate peptides and hemin are natural antioxidants, and the formation of peptide–hemin conjugates can synergistically improve antioxidant performance. Ultrasonic (US) treatment facilitates the binding of different molecules. Therefore, in this study, the effects of ultrasonic power treatments on the antioxidant activity and binding behavior of peptide–hemin conjugates were investigated. The spatial structure of the peptide–hemin conjugates was characterized using endogenous fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and circular dichroism (CD) spectroscopy, respectively. The results demonstrated that the peptide–hemin binding rate reached the highest value of 91.63% at 400 W US power, with structural changes in conjugates from α-helix to random coil structures. Additionally, US treatment increased the surface hydrophobicity and reduced the enthalpy change in conjugates. The antioxidant capacity was greatly improved and peaked at 400 W US, where DPPH and ABTS radical scavenging rates exceeded 55% and 65%, respectively. This study provided a scientific basis for the high-value utilization of US treatment on porcine blood meal resources. Full article

The global rise in metabolic disorders demands novel interventions targeting starch digestion. This study investigated two dietary phenolic acids (caffeic acid (CA) and p-hydroxycinnamic acid (p-HA)) as inhibitors of α-amylase and α-glucosidase through integrated experimental and computational approaches. Molecular docking showed distinct binding modes, and CA formed stable hydrogen bonds with catalytic residues of α-glucosidase, while p-HA interacted mainly with α-amylase via hydrophobic contacts. Enzyme kinetics revealed concentration-dependent mixed-type inhibition, with CA being more potent against α-glucosidase and p-HA against α-amylase. Spectroscopic analysis indicated both acids induced structural changes in the enzymes, with CA causing greater α-helix reduction (Δ7.03% vs. Δ2.10%) by altering the tryptophan microenvironment. Moreover, both compounds significantly suppress glucose absorption in the proximal small intestine in an ex vivo everted gut sac model, with p-HA exhibiting exceptional efficacy in the duodenum. These findings clarify structure–activity relationships and support the potential use of CA and p-HA as local intestinal agents for modulating carbohydrate absorption. Full article

β-glucans are biologically active biopolymers that influence metabolic activity and possess immunomodulatory, antitumor, anti-inflammatory, and wound-healing properties. The biological activity of β-glucans is influenced by both their primary structure and spatial conformation, which, in turn, depend on the natural source of the polysaccharides and their extraction methods. In this study, the water-soluble fraction of β-(1→3,1→6)-D-glucan, isolated from non-irradiated and irradiated Pleurotus ostreatus cryopowder pre-treated with alcohol, was investigated. Increasing the irradiation dose was found to increase the yield of the water-soluble glucan fraction. Furthermore, irradiation increased the solubility of glucans in water and reduced their bulk density and moisture content, which may be due to partial degradation of the biopolymer. According to FTIR and NMR spectroscopy, water-soluble glucan samples isolated from both irradiated and non-irradiated samples consist predominantly of β-(1→3,1→6)-D-glucan, protein, and a small amount of (1→3)-α-glucan. It was found that the triple-helix conformation of glucans in solution, assessed using Congo red analysis, did not change upon irradiation. Irradiation resulted in a dose-dependent increase in the antiradical activity of the glucans against the stable DPPH radical. Addition of irradiated glucans to sugar syrup used as a feed supplement for bee feeding resulted in a significant increase in the proline content of honey. Thus, electron irradiation is a promising method for obtaining β-glucans with high water solubility and contributes to enhancing their biological activity. Full article

This study investigated the effect of pre-cooking level of germinated highland barley pulp on the staling properties and digestibility of pre-packaged barbecued pork buns during refrigerated storage (0–9 days). The addition of barley pulp significantly delayed quality deterioration, resulting in a decreased specific volume (up to 20%) and an increased hardness (up to 71.76%) across all samples. Furthermore, it effectively inhibited the rise in starch short-range order, as evidenced by a decreased FTIR ratio of 1047/1022 cm⁻¹, and retarded the conformational transition between protein α-helix and β-sheet structures. When the gelatinization degree increased to 91.22%, rapidly digestible starch (RDS) decreased significantly while resistant starch (RS) increased. The sauce infiltration layer exhibited a higher maximum RS (23.23%) than the inner crumb (16.52%). The Glycemic Index (GI) was significantly reduced, with the lowest values observed in the BJ60 group (53.22 for the sauce infiltration layer and 60.37 for the inner crumb). α-Amylase inhibition was also enhanced with increasing gelatinization degrees. Significant correlations were found between starch structural parameters and digestibility. These results demonstrate that incorporating germinated highland barley pulp is a feasible strategy to simultaneously improve the shelf-life and nutritional quality of steamed buns. Full article

Aflatoxin B1 (AFB1) induces hepatocellular damage through its metabolite aflatoxin B1-8,9-epoxide (AFBO), which is produced in endoplasmic reticulum (ER) via cytochrome P450 (CYP450) enzymes. To investigate the effect of ferulic acid (FA) on AFB1-induced broiler liver damage, one-day-old Arbor Acres broilers were exposed to AFB1 (4 mg/kg) and treated with different doses of FA (60 mg/kg, 120 mg/kg, and 240 mg/kg) continuously for 28 days. The production performance, biochemical indicators, morphological changes, CYP450 enzymes’ expression in ER, interactions between small molecules and CYP450 enzymes, and CYP450 enzymes’ protein secondary structure were investigated. The results showed the following: (I) FA promoted broiler growth and reduced AFBO production. (II) AFB1-induced changes in serological indicators (AST, ALT, ALP, γ-GT, TBA, TG) and biochemical parameters (GST, SOD, MDA, ROS), which were reversed by FA. (III) AFB1-induced liver morphological changes and apoptosis were obviously alleviated by FA. (IV) AFB1-induced up-regulation of CYP1A5, CYP2A6, CYP2W1, and CYP3A4 in ER were reduced by FA. (V) The binding affinity of FA to CYP1A5 is lower than that of AFB1 to CYP1A5, and the binding affinity of FA to CYP2W1 is similar to that of AFB1 to CYP2W1. (VI) The contents of α helix, β sheet, β turn, and random coil in chicken CYP1A5 were 59.6%, 7.8%, 13.6%, and 19.0% respectively, and those in chicken CYP2W1 were 32.2%, 17.1%, 16.8%, and 33.9% respectively. In conclusion, FA can promote broiler growth and alleviate AFB1-induced hepatotoxicity via inhibiting and conjugating CYP450 enzymes, thus reducing AFBO formation and oxidative damage. Full article

Selective inhibition of poly(ADP-ribose) polymerase 1 (PARP1) may reduce the hematologic toxicity associated with dual PARP1/PARP2 inhibition. We performed molecular dynamics simulations for five selective inhibitors in complexes with PARP1 and PARP2, using three independent 50 ns runs per complex after docking and equilibration, followed by protein–ligand interaction fingerprint and statistical analyses. All complexes remained dynamically stable, with ligand root-mean-square deviation values generally within 0.3 nm. Comparative analysis identified three αF-helix residue pairs with nominally reduced interaction frequencies in PARP2: Asn767/Ala336, Leu769/Gly338, and Asp770/Asp339 (p < 0.05). After Benjamini–Hochberg correction for multiple comparisons, Leu769/Gly338 remained significant (q < 0.05), indicating that this pair represents the most statistically robust interaction difference within this region. Using palacaparib as the most selective inhibitor, these differences were associated with weakened or lost hydrophobic, van der Waals, and cation–π interactions in PARP2. Selective binding of modern PARP1 inhibitors appears to be associated with αF-helix-dependent interaction patterns, providing a mechanistic basis for the rational design of next-generation selective inhibitors with improved selectivity and potentially reduced toxicity. Full article

Refined wheat staple foods are widely criticized for low dietary fiber and high postprandial glycemic response, making soluble dietary fiber fortification a promising strategy for cereal improvement. This study investigated how resistant dextrin (RD) modulates wheat starch, gluten, dough, and bread quality through multiscale interactions. In wheat starch, 6% RD gave the best overall balance, reducing 14-day retrogradation from 57.2% to 48.6%, delaying gelatinization, and restricting amylose diffusion, with hydrogen bonding identified as a major contributing interaction. In gluten, RD increased water-holding capacity but weakened network integrity, as evidenced by reduced moduli, a shift in thiol–disulfide balance, secondary-structure redistribution (increased β-sheet, decreased α-helix/β-turn), and suppressed glutenin polymerization, yielding a looser microstructure. In dough, SEM and rheological results suggested that moderate RD (4–6%) may form a hydrated, polysaccharide-rich phase that fills structural voids and improves matrix continuity, partially offsetting gluten weakening and enhancing viscoelasticity. Overall, this study establishes a quantitative relationship between RD addition level, multiscale macromolecular interactions in wheat matrices, and the processing performance and quality of bakery products. Full article

In this study, we investigated the effect of ultrasound-assisted Maillard glycosylation reaction time on the structural, physicochemical, and acid-induced gel properties of Zophobas morio protein–maltodextrin (ZMP–MD) conjugates. Ultrasound treatment up to 45 min (100 kHz, 450 W, 70 °C) significantly accelerated the conjugation efficiency (15.81%) compared to that of wet heating at 70 °C for 6 h (13.62%) (p < 0.05). Fourier transform infrared spectroscopy (FT-IR) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses confirmed that both Maillard glycosylation methods formed ZMP–MD conjugates. In addition, the results for secondary structure, surface hydrophobicity, and zeta potential revealed that the ultrasound treatment promoted greater protein structural unfolding, decreasing α-helix while increasing β-sheet and random coil content compared to wet heating. These changes in structural and physicochemical properties of ZMP–MD conjugates impacted the glucono-δ-lactone (GDL)-based acid-induced gel properties. Even though Maillard glycosylation with MD weakened gel properties compared to native ZMP, the gel obtained after 45 min of ultrasound treatment exhibited a higher storage modulus, gel strength, and water-holding capacity than the wet-heated ZMP–MD gel. In conclusion, these findings suggest that properly controlled ultrasound-assisted Maillard glycosylation can modify protein structure, potentially improving its gel properties. Full article

The immunomodulatory potential of natural polysaccharides is often limited by their structural complexity and high molecular weight. In this study, DFIP-A3-1 (M_w = 8.68 × 10³ g/mol) was obtained from the leaves of Isatis indigotica Fort. by ultrafiltration, DEAE-650M, and Sephadex G-100 chromatography, followed by acid degradation. Fortunately, DFIP-A3-1 exhibited the most potent immunostimulatory activity in vitro. HPGPC, HPSEC-MALLS-RID, GC-MS, FT-IR, Congo red tests, SEM, and AFM were used to characterize their structure, and 1D/2D NMR was used for further investigation of DFIP-A3-1 for in-depth structural clarification. DFIP-A3-1 was primarily composed of Rha and Gal. Based on methylation and NMR analyses, the structure of DFIP-A3-1 was elucidated as follows: →1)-β-Galp-(4→1,4)-α-Rhap-(2→1,4)-α-Rhap-(2→1)-β-Galp-(6→1)-β-Galp-(6→1,6)-β-Galp-(3→1,6)-β-Galp-(3→. Furthermore, DFIP-A3-1 was found to exhibit a triple-helix conformation. DFIP-A3-1 markedly upregulated the secretion of NO, IL-6, and TNF-α and enhanced the mRNA expression levels of their related genes in RAW 264.7 cells. Moreover, DFIP-A3-1 activated p-IκBα, p-p65, and TLR4, while co-treatment with TAK-242 markedly suppressed the expression of these pathway-related proteins. All of the aforementioned findings suggested that DFIP-A3-1 is a promising natural immunomodulatory drug deserving of additional research and use. Full article

To improve the flavor quality and antioxidant activity of walnut gluten peptides, gluten was extracted from defatted walnut meal by alkaline solubilization and acid precipitation, hydrolyzed with alkaline protease to prepare antioxidant peptides, and further modified by the Maillard reaction. The optimal sugar source was selected by single-factor experiments, and reaction conditions were optimized by response surface methodology. Peptide conformational changes were characterized by UV, fluorescence, DSC, FTIR, and SEM, while changes in amino acid composition, flavor properties, and antioxidant activity were systematically evaluated. Fructose was identified as the optimal sugar source. The optimal reaction conditions were a peptide-to-sugar ratio of 1:1.2, 78.5 °C, initial pH 7.6, and 2 h reaction time, under which the sensory score reached 8.5 and DPPH radical scavenging activity reached 66.92%. Maillard modification markedly altered peptide conformation, as shown by increased UV absorbance, decreased intrinsic fluorescence intensity with a red shift, an increase in denaturation temperature from 80 °C to 100 °C, reduced α-helix content, increased β-sheet content, and transformation of the microstructure from a loose porous morphology to dense block-like aggregates. Free amino acid content increased initially and then decreased, whereas total essential amino acids were largely retained, indicating that the overall nutritional composition was preserved. However, further evaluation of digestibility and bioavailability is required to confirm nutritional value. These findings provide a feasible strategy for improving the flavor and functional properties of walnut gluten peptides and support their high-value utilization. Full article