Egg White Ovalbumin Research Articles

Dry-heat-induced phosphoserine-specific fragmentation of ovalbumin

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, S68 and S344. 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.

The immune-enhancing activity of egg white ovalbumin hydrolysate prepared with papain via MAPK signaling pathway in RAW 264.7 macrophages

The immune-enhancing activity of egg white ovalbumin hydrolysate prepared with papain via MAPK signaling pathway in RAW 264.7 macrophages

Egg white composition, antioxidant capacity, serum and yolk lipids and oxidative damage of the oviduct magnum in laying hens fed diets contaminated with different concentrations of cadmium

Total of 384 healthy 38-week-old hens were randomly divided into four treatments. Layers in four groups were fed a basal diet and a basal diet with Cd at the level of 15, 30 and 60 mg/kg for nine weeks. Results showed that Cd could dose-dependently deposited in magnum and a positive correlation occurred between the accumulation of Cd in magnum and Cd content in egg whites. When compared with control group, 60 mg/kg Cd decreased magnum ovomucin, ovalbumin, lysozyme and ovomucoid gene expressions, but increased avidin gene expression obviously. Hens receiving 60 mg/kg Cd exhibited a significant decrease in egg white ovalbumin content and its proportion in total protein and increase in total cholesterol and LDLC levels in serum and yolk. The level of GSH and activities of T-SOD and CAT in magnum and GSH-Px activity in egg white were decreased significantly, while MDA level in both magnum and egg white was increased obviously in 60 mg/kg Cd group. Besides, Cd induced oxidative stress, inflammation, endoplasmic reticulum stress (ERS) and mitophagy accompanied by a significant up-regulation of the expressions of Keap1, IL1β, TNFα, NF-κB, p65, p-p65, Grp78, CHOP, ATF4, ATF6, IRE1α, Grp94, PINK1, Parkin, Fundc1, GRP75, VDAC1, MCU, MFF, Bnip3 and LC3I/II and a significant down-regulation of the expressions of Nrf2, HO-1, SOD1, SOD2, SOD3, MFN1, MFN2 and PGC1α. These results indicated that Cd can increase serum and yolk cholesterol level and induce magnum oxidative stress, inflammation, ERS and mitophagy through Nrf2/NF-κB and IRE1α/IP3R/GRP75/VDAC1/MCU pathways, thus disrupting egg white composition. Highlights Cd exposure disrupted the synthesis of egg white protein in oviduct magnum and destroyed antioxidant status and protein composition in egg white. Cd exposure significant enhanced serum and yolk total cholesterol and LDL cholesterol levels. Cd exposure induced magnum oxidative stress, inflammation, ERS and mitophagy through Nrf2/NF-κB and IRE1α/IP3R/GRP75/VDAC1/MCU pathways.

Effects of kappa-carrageenan on egg white ovalbumin for enhancing the gelation and rheological properties via electrostatic interactions

The protein-polysaccharide system is natural, and it has been widely applied in food manufacturing in recent years. However, the interactions in the system might be affected by numerous factors and this research investigated the effects of κ-carrageenan (κ-C) on the structure, interaction, and rheological characteristics of egg white ovalbumin (OVA) before and after heating. The zeta potential was adopted to show the surface charge of mixtures and its combination with turbidity test was used to discover the maximum associative interaction at the critical mixing ratio of κ-C: OVA. The results evidenced that the electrostatic interaction formed between OVA and κ-C. The critical ratio of OVA: κ-C (w/w) at 92:8 showed the minimum net charge (−0.5 ± 0.3 mV) and the maximum turbidity (0.122 ± 0.001 cm −1 ). All κ-C/OVA mixtures were observed shear thinning behaviour. The mixtures at 92:8 performed the highest apparent viscosity ( η ) and remained the maximum complex modulus ( G *) in the thermal cycle. The κ-C/OVA complex network was observed stronger than pure κ-C or OVA through the confocal scanning laser microscopy (CLSM). The rheological properties of the 92:8 mixtures supported the strongest electrostatic interactions between κ-C and OVA, corresponding to the largest aggregates structure in the CLSM images. A schematic model was further verified at the secondary structure of OVA using Fourier transform infrared (FTIR) spectroscopy. This study provides instructions to design innovative food systems that contain κ-C and OVA. • Ovalbumin (OVA) and κ-C were combined via electrostatic interaction. • κ-C induced the aggregates formation and the largest aggregates formed at 92:8. • The 92:8 mixtures showed the highest apparent viscosity ( η ). • The complex modulus ( G *) of 92:8 mixtures was the highest during thermal gelation. • The critical mixing ratio of OVA/κ-C mixtures occurred at 92:8.

Amyloid-like aggregation influenced by lead(II) and cadmium(II) ions in hen egg white ovalbumin

The aggregation of proteins into fibrillar, amyloid-like aggregates generally results in an improved, positive effect on various techno-functional properties within food products, such as gelation, emulsification, and foam stabilization. These highly stable structures, characterized by their repetitive, β-sheet rich motifs, may develop as the result of the thermal treatment of protein-rich food products. Heavy metal ions can influence amyloid-like aggregation of food proteins. Lead(II) and cadmium(II) represent some of the most abundant and common environmental water and food pollutants.In this work, the influence of heavy metal ions, lead and cadmium on amyloid-like aggregation of ovalbumin at high temperatures (90 °C) and under acidic conditions (pH 2.0) was investigated. Ovalbumin is used as a general model for how heavy metals can affect amyloid-like aggregation of a food protein. Structural changes were monitored via Thioflavin T and 8-Anilino-1-naphthalenesulfonic acid fluorescence, Fourier-Transform infrared spectroscopy, atomic force microscopy, dynamic light scattering, as well as computational analyses. The obtained results indicate that the added heavy metal ions bind to different sites within ovalbumin prior to thermal treatment. Lead binding sites are closer to the hydrophobic regions of an protein, while cadmium ion binding sites are more exposed. This specific binding of metal ions affects the morphologies of amyloid-like aggregates, resulting in lead-induced branching of amyloid-like fibrils, or cadmium-induced tangling of fibrils into dense amyloid clusters. This additive effect of heavy metal ions is most evident in ovalbumin samples which contain a mixture of both heavy metal ions.

Pasteurization induced protein interaction decreased the potential allergenicity of ovalbumin and ovomucoid in egg white.

Approximately 9.9% of young children in China suffer from egg allergies. Ovalbumin (OVA) and ovomucoid (OVM) are both the main allergens with higher allergenicity in egg white. The previous studies mainly focused on the effects of pasteurization on the structure and allergenicity of the isolated protein itself. The effects of the interaction between OVA and OVM on their spatial structure and allergenicity under pasteurization are still unclear. Therefore, in this study, the spectroscopic, immunological, and cytological methods were used to investigate the effects on OVA and OVM by their interactions which were induced by the following pasteurization, heating for 10min at 60, 65, and 70 °C, respectively. Results indicated that OVA and OVM could form macromolecular aggregates by their interaction at 70 °C, and their solubility was decreased while turbidity was increased. The spatial structures of OVA and OVM were both changed by their interaction, when pasteurization temperature was at 70 °C the exposure of their hydrophobic groups and α-helix content were decreased while their β-sheet was increased. The potential allergenicity of OVA and OVM was also changed, which showed that the immunoglobulin G (IgG)-binding ability of OVA and OVM could be increased, and their IgE-binding ability was decreased a bit. The releases of interleukin 4 (IL-4), IL-6, β-HEX, histamine and tumor necrosis factor alpha (TNF-α) from OVA-OVM-induced KU812 cells were all decreased at 70 °C. Therefore, according to the results, if the liquid egg products were pasteurized for 10min, the temperature of 70 °C should be carefully considered. © 2022 Society of Chemical Industry.

Relationship of co-gelation and co-aggregation on egg white ovalbumin-lysozyme heteroprotein complex: Formation and thermodynamics

This study aimed to establish binary protein system on egg white ovalbumin (OVA) -lysozyme (LYS), and investigated the relationship between co-aggregation and co-gelation. We focused on the formation of OVA-LYS complex, the typical thermo-dynamically favored coacervation process, in terms of gelling properties, microstructure and thermodynamics. Benefited from synergistic effects during co-gelation, the thermally induced gels of OVA-LYS complex formed at extremely low protein concentration (18 mg/mL) and showed higher storage modulus with increasing LYS concentration. Moreover, the rising particle size, reduced zeta potential, unordered secondary structure and strengthened protein chain were observed with the addition of LYS. Remarkably, the divalent ions enhanced thermodynamic stability of OVA-LYS complex, although the growth of aggregates units were prevented by ions at room temperature. ITC and molecular docking analyses revealed the binding affinity stoichiometry and combination phase, which were closely related to the decrease of minimum energy resulted from the formation of hydrogen bond.

Utilising Smartphone Light Sensors to Measure Egg White Ovalbumin Concentration in Eggs Collected from Yinchuan City, China

Cost-effective, portable, and rapid smartphone sensors will play a critical role in bringing chemical detection technologies from central laboratories to simple laboratories, such as those of schools in less-developed area. In this work, we study whether eggs in Yinchuan have a higher concentration of ovalbumin than that in ordinary eggs. We summarise previous research on sensors built inside smartphones, as well as some developments in the current literature, and develop a simple experimental procedure that utilises the light sensor of a smartphone to analyse light intensity and thereby determine the ovalbumin content of egg white cheaply and quickly. Most of the materials required for conducting this experiment can be easily found in simple school laboratories, and it allows solution concentrations to be quickly assessed by high school students in the data collection and analysis phase. Indeed, the data collected using smartphone light sensors were similar to those obtained using a spectrometer. It was concluded that egg white ovalbumin concentration in eggs collected from Yinchuan is higher than that in ordinary eggs.

Dual-function peptides derived from egg white ovalbumin: Bioinformatics identification with validation using in vitro assay

Abstract A complete integrated bioinformatics approach was developed to identify angiotensin-converting enzyme (ACE) and dipeptidyl peptidase-4 (DPP-4) inhibitory peptides from egg white ovalbumin. The sequence of the protein was initially obtained from the NCBI database followed by in silico digestion using different enzymes or combination of enzymes. The results showed that 71 peptides were produced. Their bioactivities were then predicted based on the amino acid compositions and sequences as well as the peptide interactions with ACE and DPP-4. Ten highly potential peptides (CF, KM, ELPF, AM, ADHPF, LPR, PR, FR, PRM and GR) were chosen as they obtained p-value less than 0.01. The results from the in vitro validation experiment showed that all peptides were able to inhibit the ACE and DPP-4. Overall, this study underlined the in silico approach as an alternative way for bioactive peptide discovery which could tremendously reduce the cost and time of research.

Preparation of Tungstotellurate(VI)-coated Magnetic Nanoparticles for Separation and Purification of Ovalbumin in Egg White

Abstract Tungstotellurate(VI)-coated magnetic nanoparticles (MNP) were prepared by immobilization of tungstotellurate(VI) salt onto the surface of branched polyethyleneimine (PEI)-modified magnetic nanoparticles via electrostatic interaction. The structure and composition of TeW@MNP were confirmed by characterization with FT-IR, EDS and SEM. The obtained TeW@MNP composite had proven to be a promising adsorbent for the adsorption of ovalbumin in egg whites. Approximately 0.5 mg of TeW@MNP composite gave rise to a maximum adsorption efficiency of 91.6% for 100 μg mL–1 ovalbumin in 200 mL of sample solution at pH 4.0 (BR buffer). The retained ovalbumin was readily recovered by using 0.1% SDS as a stripping reagent, providing a recovery of 98.1%. The adsorption behavior of ovalbumin fitted Langmuir model, corresponding to a theoretical adsorption capacity of 373 mg g–1. The TeW@MNP composite was practically applied to the selective isolation of ovalbumin from egg whites, and SDS-PAGE assay results clearly indicated that the ovalbumin with high purity was obtained. The above experimental results illustrated the great application potentials of polyoxometalates for protein isolation and purification and extended the application scope of polyoxometalates in life science field.

Hydroxyl radical-induced early stage oxidation improves the foaming and emulsifying properties of ovalbumin.

As the most abundant protein in chicken eggs, ovalbumin plays an important role in the processing of high value-added poultry products. The present study investigated the effects of hydroxyl radical-induced early stage oxidation on the physicochemical and interfacial properties of chicken egg white ovalbumin. Protein carbonyl content of ovalbumin increased (from 0.78 to 1.13nmol/mg) with the oxidation time (0-5h), while free sulfhydryl content (from 0.43 to 0.09nmol/mg) and free amino group content (from 0.49 to 0.43nmol/mg) decreased. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed that the exposure of ovalbumin to hydroxyl radicals caused self-cross-linking and resulted in the formation of dimers and trimers. Accompanied by these changes, the surface hydrophobicity of ovalbumin was enhanced about 1.5-fold with the deepening of oxidation, and the value of zeta potential became more negative (from -7.15 to -20.51 mv). About 2 h of moderate oxidation improved the foaming and emulsifying properties of ovalbumin (1.2-fold to 1.8-fold), while excessive oxidation (3h) decreased these interface properties. Hydroxyl radical-induced oxidation changed the surface chemical groups and structures of ovalbumin, thereby affecting the surface properties. The foaming and emulsifying properties of ovalbumin could be improved by oxidation, increasing the application possibilities of ovalbumin in the food interface system.

A novel ACE inhibitory peptide derived from alkaline hydrolysis of ostrich (Struthio camelus) egg white ovalbumin

Abstract In this research, ovalbumin (OOW), one of the major components in ostrich egg white, was purified by anion exchange chromatography. Then, the purified OOW was subjected to alkaline hydrolysis (0.25 M NaOH) at 40 °C for 2–10 h. The best angiotensin I-converting enzyme (ACE) inhibitory activity was observed at 8 h of hydrolysis. The OOW hydrolysate obtained at 8 h (8 h-hOOW) was purified by the reversed-phase high-performance liquid chromatography (RP-HPLC). The resulting peptide, YV, exhibited an IC50 value of 63.97 μg/mL. Using a Lineweaver-Burk plot, YV was determined to be a competitive inhibitor, and the inhibition constant (Ki) was found to be 55.20 μg/mL. The molecular docking analysis revealed that the binding between YV and the S1 and S2 pocket sites of ACE was mainly stabilized by a hydrogen bond. Moreover, YV maintained ACE inhibitory activity after gastrointestinal digestion and showed no cytotoxic effects on human red blood cells, human keratinocyte cells (HaCaT) and human lung fibroblasts cells (MRC-5). An in vitro test of intestinal absorption showed that YV had a high potential for absorption into the Caco-2 cell monolayer model. Therefore, these results suggest that the YV peptide can be applied for the development of novel natural antihypertensive products.

Ultrasonic Characterization of Amyloid-Like Ovalbumin Aggregation.

Thermal processing conditions, pH, and salt content affect the formation of egg white ovalbumin amyloid, which was investigated using high-precision measurements of ultrasonic velocity and attenuation. These were related to fluorescence and particle size measurements. Fluorescence changes indicated the formation of amyloid-like aggregates that was enhanced by increasing time–temperature treatments. The ultrasonic velocity of ovalbumin after heating at neutral pH (60 min at 70 or 80 °C) was lower than that of unheated ovalbumin, whereas the attenuation was higher. The decrease in the velocity represents increased compressibility associated with a change in the compactness of the protein, whereas changes in attenuation are due to protein conformational changes. Heating ramp studies revealed transitions at approximately 58 and 73 °C. During heating at a constant temperature, the ultrasonic velocity decreased slowly with increasing heating time, indicating an increase in ovalbumin compressibility. It is suggested that the obtained amyloid-like ovalbumin aggregates contain a compact core surrounded by loosely packed protein segments.

Effect of acid treatment on allergenicity of peanut and egg.

Many food experts have studied various treatments or processing techniques in order to develop hypoallergenic foods. In a previous study, acid treatment dramatically mitigated the allergenicity of peanut, especially Ara h 2. Gel electrophoresis showed that most protein bands of acid-treated peanut were not detected, but protein bands of egg white became weaker and broader by acid treatment. In immunoblotting using a rabbit antibody, the antigenicity against ovalbumin or ovomucoid in acid-treated egg white was decreased but the antigenicity against Ara h 1 or Ara h 2 in peanut treated with pH 2 acetic acid was completely undetected. The allergenicity of ovalbumin and peanut fell significantly to 1/1022 and 1/5380, respectively, when measured as IC50 in the sample treated with pH 2.0 acetic acid. This study showed that acid treatment was more effective in peanut and barely effective in ovomucoid. This may contribute to the development of hypoallergenic food and clinical management of food allergy. © 2016 Society of Chemical Industry.

A Kinetic Study of Ovalbumin Fibril Formation: The Importance of Fragmentation and End-Joining

The ability to control the morphologies of biomolecular aggregates is a central objective in the study of self-assembly processes. The development of predictive models offers the surest route for gaining such control. Under the right conditions, proteins will self-assemble into fibers that may rearrange themselves even further to form diverse structures, including the formation of closed loops. In this study, chicken egg white ovalbumin is used as a model for the study of fibril loops. By monitoring the kinetics of self-assembly, we demonstrate that loop formation is a consequence of end-to-end association between protein fibrils. A model of fibril formation kinetics, including end-joining, is developed and solved, showing that end-joining has a distinct effect on the growth of fibrillar mass density (which can be measured experimentally), establishing a link between self-assembly kinetics and the underlying growth mechanism. These results will enable experimentalists to infer fibrillar morphologies from an appropriate analysis of self-assembly kinetic data.

Quantitative characterization of nonspecific self- and hetero-interactions of proteins in nonideal solutions via static light scattering.

The dependence of static light scattering upon the compositions of solutions including hen egg white ovalbumin, hen egg white ovomucoid, ribonuclease A, and binary mixtures of these proteins at total concentrations of up to about 40 g/L were measured at different values of the pH and ionic strength. At the pH values of measurement, ovalbumin and ovomucoid have a net negative charge and ribonuclease A has a net positive charge. The observed dependence of scattering intensity upon solution composition may be accounted for by an extension of previously formulated equivalent hard particle models that allows for the presence of both repulsive interactions between like species and attractive interactions between unlike species in mixtures of positively and negatively charged proteins.

Transport of Egg White ACE-Inhibitory Peptide, Gln-Ile-Gly-Leu-Phe, in Human Intestinal Caco-2 Cell Monolayers with Cytoprotective Effect

The purpose of this study was to investigate the transepithelial transport and cytoprotective effect of Gln-Ile-Gly-Leu-Phe (QIGLF), an ACE-inhibitory peptide derived from egg white ovalbumin, in human intestinal Caco-2 cell monolayers. The results showed that QIGLF could be absorbed intact through Caco-2 cell monolayers with a Papp value of (9.11 ± 0.19) × 10-7 cm/s (transport kinetic parameters: Km, 32.37 ± 12.59 mM; Vmax, 1.23 ± 0.49 μM/min cm2). The transport was not significantly decreased by sodium azide and Gly-Pro, an ATP synthesis inhibitor and a peptide transporter 1 (PepT1) substrate, respectively, suggesting that transport of QIGLF was not energy-dependent and carrier-mediated. In addition, wortmannin, a transcytosis inhibitor, had little effect on the transport, suggesting that endocytosis was not involved in the transport of QIGLF. However, the transport of QIGLF was increased significantly in the presence of cytochalasin D, a tight junction disruptor, suggesting that paracellular transport via tight junctions was the major transport mechanism for intact QIGLF across Caco-2 cell monolayers. Moreover, QIGLF was added to Caco-2 cells followed by addition of H2O2, and exhibited significant cytoprotective effect in Caco-2 cells against oxidative stress induced by H2O2.

Degranulation of basophilic leukemia cells on branched-chain peptide array with an OVA–DNP double epitope

Simple method for identification of heterovalent allergen epitopes was constructed to reflect the allergic reaction initiated by the cross-linking of the IgE receptors. The peptide array-based degranulation assay that enables interaction between solid support-bound peptide pairs and IgE sensitized basophilic leukemia cells was developed. Using lysine side chains, a chicken egg white ovalbumin (OVA) epitope and a dinitrophenol (DNP) modified amino acid was synthesized in the branched-chain peptide array. The basophilic leukemia cells sensitized with anti-OVA IgE and anti-DNP IgE induced degranulation directly on the branched-chain peptide array. The OVA–DNP double peptide disk caused the release of 37.5% of β-hexosaminidase whereas the DNP-only peptide disk caused the release by 20.9%. These results show that the double epitope branched-chain peptide array can induce degranulation, and would represent a suitable model for screening the heterovalent epitope pairs of allergens.

Polydopamine-graft-PEG antifouling coating for quantitative analysis of food proteins by CE

In this paper, firstly the surface plasma resonance (SPR) was used to evaluate the antifouling property of polydopamine-graft-poly(ethylene glycol) (PEG) copolymer coating, and then the quantitative analysis of food proteins (such as hen eggs and milk powder) was investigated by capillary electrophoresis (CE) method using polydopamine-graft-PEG copolymer coated capillary. The great separations of lysozyme, conalbumin and ovalbumin from hen egg white could be achieved in phosphate–citrate buffer (pH 3.20) with an applied voltage of +20 kV in polydopamine-graft-PEG copolymer coated capillary. The range of protein recovery percentage of the three kinds of egg white proteins was 96.67% to 101.02%. According to the quantitative analysis results, the protein content of lysozyme, conalbumin and ovalbumin in hen egg white was 13.268 mg mL−1, 28.360 mg mL−1 and 157.418 mg mL−1, respectively. Whey proteins (β-lactoglobulin A, β-lactoglobulin B and α-lactalbumin) in nonfat milk powder could be separated completely with an applied voltage of −20 kV in sodium tetraborate buffer (pH 8.5). The protein recovery of β-lactoglobulin A, β-lactoglobulin B and α-lactalbumin was in the range of 86.40–94.38%. Finally, the quantitative protein content of β-lactoglobulin A, β-lactoglobulin B and α-lactalbumin in nonfat milk powder was 1.418 mg mL−1, 0.129 mg mL−1, and 0.073 mg mL−1, respectively. Also the egg white proteins could be separated consecutively 25 times without a noticeable loss in separation efficiency using polydopamine-graft-PEG copolymer coated capillary in one day.

Fibrillation of Egg White Ovalbumin: A Pathway via Biomineralization

Here we report the fibrillation of egg white ovalbumin (OVA) induced by the biomineralization of two alkali halides (KCl, NaCl) in the Langmuir-Blodgett (LB) film of OVA. The pressure-area isotherm of OVA shows the salt-induced increment of apparent area/monomer of OVA. Fibrillation of OVA in the LB film is monitored by FE-SEM imaging. Formation of fibrillar aggregates is concomitant with an increase of salt concentration. HR-TEM and EDX measurements allowed us to identify nanostructured crystals of salt, which are associated with this fibrillar structure. FTIR spectroscopic study of the amide band in LB films as well as CD spectroscopy in solution qualitatively indicates the increase in β-sheet to α-helix ratio in the presence of salt, indicating unfolding of protein. We suggest that the ion attachment to the peptide chain leads to unfolding and that subsequent recrystallization in the transferred monolayer leads to fibrillation of protein as well as biomineralization of alkali halide salts. This finding demonstrates that the fibrillation of OVA is induced by the biomineralization of alkali halides.