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Hydrogels could be used as wound dressings, but most protein-based hydrogels lack anti-bacterial effects. Here, we successfully prepared a silver ion cross-linked thiolated protein hydrogel (thiolated Ovalbumin and Gelatin, O3G7). The wound photographs showed that the healing rate (96.23 %) of hydrogel-treated mice was higher than the control group. Meanwhile, the hydrogel increased the granulation tissue's total protein content. Furthermore, it significantly increased the collagen content, consistent with the results of Masson's trichrome (MT) staining and immunohistochemical analysis of type I collagen (ColI). The results of hematoxylin and eosin (H&E) staining showed the growth and proliferation of inflammatory cells, granulation tissue, fibroblasts, blood vessels and hair follicles in acute wounds. O3G7 hydrogel had fewer inflammatory cells and more neovascularization, and hair follicle tissue and intact epidermis could be observed. The results of immunofluorescence and immunohistochemistry showed that the O3G7 group reduced the expression of tumor necrosis factor (TNF)-α (56.87 % of the control group) and upregulated the expression of transforming growth factor (TGF)-β (1.29 times of the control group). These results suggest that O3G7 hydrogel significantly affects the healing of acute wounds. This study demonstrates that hydrogels prepared from food-derived proteins will be promising and bio-safe candidates in bioengineering., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

There is a huge demand to identify the sex of unhatched fertilized eggs for laying industry and to understand the differences between male and female eggs as early as possible. Then the molecular mechanisms of sex determination and sex allocation in chicken were revealed. Therefore, TMT proteomic was applied to characterize the variation of molecular matrix between unhatched male and female egg yolks. A total of 411 proteins were identified and 35 differentially expressed proteins (DEPs), including 375332005, 015809562, 763550308 (upregulated, UPs) and 1337178851, 89000557, 89000581 (downregulated, DPs), etc. were confirmed between them. Gene ontology analyses showed that DEPs were mainly involved in response to stimulus, distributed in the extracellular region and participated in binding; KEGG analyses showed that few DPs were participated in cell growth and death, transport and catabolism, signaling molecules, interaction and were enriched in ubiquitin mediated proteolysis, endocytosis, ferroptosis, etc. metabolic pathways. Moreover, most of the DEPs and related metabolic pathways were associated with sex hormones. More importantly, this study supports maternal sex-allocation theory and extends our understanding of the molecular mechanism of sex determination and differentiation in avian. Which also provides a powerful evidence for ovo sexing of unhatched fertilized domestic chicken eggs by nondestructive approach and will be of great significance to eggs processing and production., (Copyright © 2022. Published by Elsevier Inc.)

The objective of this study was to investigate the effects of repeated freeze-thaw cycles on microorganisms, amino acid composition profile, chemical composition, mineral concentrations, water mobility, and fat of beef and chicken meats. Pure cultures of specific fungi and bacteria were separately injected into the minced meat. Apart from Pseudomonas, the total count of microorganisms significantly increased (P < 0.05) during refreezing treatment with the increase of storage period in both beef and chicken meats. During freezing treatment, the total count of Staphylococcus aureus, spore forming bacteria, and lactic acid bacteria were meat-type dependent. In conclusion, freeze-thaw cycles increased the microbial counts and decreased the water holding capacity, amino acids, and mineral concentrations of beef and chicken meats., (Copyright © 2021. Published by Elsevier Ltd.)

In this study, a proteome analysis of Tibetan chicken egg yolk as well as the comparison to that of lowland chicken were performed by label-free quantitative proteomics. A total of 135 proteins were identified and abundances of 19 of these proteins were significantly different between these two groups. These differential proteins were mainly associated with oxidative stress, defense, energy metabolism and tissue development through bioinformatics analysis. To further verify the species-specific diversity of the antioxidant capacity, the antioxidative activities of egg yolk proteins were further invested in vitro and in Caco-2 cells. It was observed that both Tibetan and lowland chicken egg yolk proteins showed antioxidant activities, but the former exerted a much stronger effect. PIT54 and glutathione peroxidase 3 were considered to be antioxidant-related candidate proteins. These results provide substantial evidence for the molecular mechanisms of enhancing physical activity levels of egg yolk proteins, especially with regard to the cross-species protective mechanisms against oxidative stress., Competing Interests: Declaration of Competing Interest The authors declare that ‘NO Conflict of interest’ exist in this research article., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The solvated mercuric ion (Hg 2+ ) from industrial pollutants are highly toxic to the ecological environment and human health. Driven by urgent need for the selective and sensitive detection of Hg 2+ , a magnetic relaxation switching (MRS) based on Fe 3 O 4 nanoparticles (NPs) was designed. Practically, the concentrations of Hg 2+ in industrial pollutant is usually much higher than the detection range. Thus, gold nanoparticles (AuNPs) were synthesized on the surface of Fe 3 O 4 NPs to enable the visual detection of Au@Fe 3 O 4 NPs. The presence of Hg 2+ in sample can specifically cause the aggregation of Au@Fe 3 O 4 -aptamers NPs through T-Hg 2+ -T base pairs, leading to the change in transverse relaxation time T 2 value of detection solution. The MRS sensor showed excellent response for Hg 2+ ions in the range of 10 nM-100 nM and 100 nM to 5 μM. A highly sensitive and selective measurement of Hg 2+ was obtained with a limit of detection of 2.7 nM. Noticeably, the visual detection can qualitatively analyze the Hg 2+ beyond 5 μM by naked eye without advanced instrumentation and skilled operators., Competing Interests: Declaration of Competing Interest All authors declare that they have no conflict of interest to this work. We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This experiment was conducted to explore the differences of serum steroid hormones with age and sex in hen eggs during incubation periods for identification of males and females. The concentrations of estrone (E1), estradiol (E2), estriol (E3), testosterone (T), androstenedione (A4), and dihydrotestosterone (DHT) in serum were measured by enzyme-linked immunosorbent assays in chicken embryos on 8, 10, 12, 14, and 16 D, respectively. During the development of chicken embryo, egg weight loss was closely related to age but no sex. However, it was found that both age and sex significantly affected hormones and had obviously more effect on androgens levels. Besides E2 and T, other steroids such as E1, A4, and DHT were also significantly correlated with sex (P < 0.05). Notably, the level of T and the ratio of T to E2 were significantly higher in males than females (P < 0.05). The ratio of E1 to E2 displayed different trends in different sexes, which increased in males but decreased in females. The distribution proportions of androgens and estrogens kept stable level during the late hatching periods of 12 to 16 D. The sex differences of steroids were more obvious at the late hatching stage through PCA. These suggested that the serum hormones differences in male and female embryos played a vital role in sexual differentiation. These findings not only provided the theoretical basis for sex determination of fertilized eggs in egg-laying hen strains, but also contributed to develop a non-invasive way to sex determination of fertilized eggs to meet the modern commercial application., (© 2019 Poultry Science Association Inc.)

Preserved egg, a traditional Chinese egg product, is regarded as an anti-inflammatory food in traditional Chinese medicine. This study was aimed to examine anti-inflammatory effect of the simulated gastrointestinal digestive products of whole preserved egg (DWPE), preserved egg white (DPEW), and preserved egg yolk (DPEY) on lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The results demonstrated that DWPE, DPEW, or DPEY inhibited the LPS-induced secretion of Nitric oxide (NO), without marked cytotoxicity. The DWPE, DPEW, and DPEY significantly suppressed the secretion of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α and interleukin (IL)-6. Particularly, the inhibition rate of DPEW on NO, IL-6, and TNF-α could reach 25 to 27%, 31 to 42%, and 26 to 38%, respectively (P < 0.05). Furthermore, the DPEW and DPEY downregulated the gene expression of Cyclooxygenase-2 and inducible nitric oxide synthase in a dose-dependent manner. Taken together, this study indicated that DWPE, DPEW, and DPEY, especially DPEW, might serve as functional food for anti-inflammatory therapy., (© 2019 Poultry Science Association Inc.)

In addition to small amounts of minerals and carbohydrates, most of the dry matter of chicken egg white is protein, making egg white an ideal resource for obtaining food proteins. Ovalbumin (OVA), which accounts for more than 50% of the total egg white protein, is one of the most widely studied food proteins due to its multiple functional properties, and it has also been used as a model protein molecule in many research fields. The objective of this study was to develop a simple and rapid method for the purification of OVA from egg whites on large scale. First, OVA was separated from ovomucin, ovotransferrin, and ovomucoid by polyethylene glycol (PEG) concentration, using the following optimal parameters: the PEG concentration was 15%, the pH was 6.5, the salt concentration was 100 mmol/L, and the operating temperature was 10°C. The OVA-rich supernatant obtained from PEG precipitation was further purified by isoelectric precipitation at a pI of 4.5 and a temperature of 4°C, and the purified OVA was obtained with at a purity of 95.1% by HPLC, with a yield of 46.4%. After the extraction of OVA, the PEG solution was vacuum dried and then utilized cyclically in the PEG precipitation steps. The whole purification process could be finished within 2 to 3 h at a scale of several kilograms of egg white. This method has the advantages of rapidity, simplicity, low cost, and ease of scalability., (© 2018 Poultry Science Association Inc.)

A series of different eggshell membrane (ESM) and chitosan (CS) blend films (ESM/CS) were prepared for wound-care dressing. The appearance, transparency and microstructure of the films were characterized. Several wound care-related properties such as the film integrity in solution, pH, protein (BSA) and wound fluid absorption capacity as well as the antibacterial property of ESM/CS films were evaluated. The blend films were more stable than CS film after 95 h of incubation in solution. The integrity of the blend films improved significantly at the cost of a small insignificant decrease in wound fluid absorption capacity. Besides, the blend films provided an acidic environment (pH = 5.86) for wound healing. The swelling properties of ESM contributed significantly to the increase of BSA absorption capacity of the blend films (from 46.57 mg/g of CS film to 61.07 mg/g of blend film) and helped absorb more nutrients to promote the proliferation and migration of fibroblasts. Addition of CS to ESM also enhanced the antibacterial activity of the films significantly. The results indicated that the EMS/CS blend films with 0.01 g ESM/mL CS solution showed the highest high potential to be used as a wound-care dressing for humans as well as animals., (Copyright © 2018 Elsevier B.V. All rights reserved.)

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 1.13 nmol/mg) with the oxidation time (0-5 h), while free sulfhydryl content (from 0.43 to 0.09 nmol/mg) and free amino group content (from 0.49 to 0.43 nmol/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 (3 h) 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., (© 2018 Poultry Science Association Inc.)

Ovomucin (OVM) plays an important role in inhibiting infection of various pathogens. However, this bioactivity mechanism is not much known. Here, the role of sialic acid in OVM anti-virus activity has been studied by ELISA with lectin or ligand. Structural changes of OVM after removing sialic acid were analyzed by circular dichroism and fluorescence spectroscopy. OVM could be binding to the hemagglutinin (HA) of avian influenza viruses H 5 N 1 and H 1 N 1 , this binding was specific and required the involvement of sialic acid. When sialic acid was removed, the binding was significantly reduced 71.5% and 64.35%, respectively. Therefore, sialic acid was proved as a recognition site which avian influenza virus bound to. Meanwhile, the endogenous fluorescence and surface hydrophobicity of OVM removing sialic acid were increased and the secondary structure tended to shift to random coil. This indicated that OVM molecules were in an unfolded state and spatial conformation disorder raising weakly. Remarkably, free sialic acid strongly promoted OVM binding to HA and thereby enhanced the interaction. It may contribute to the inhibition of host cell infection, agglutinate viruses. This study can be extended to the deepening of passive immunization field., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In order to broaden the antimicrobial action spectrum of lysozyme against Gram-negative bacteria, different partially reduced lysozyme derivatives were obtained by reducing the R-S-S-R bonds of lysozyme using the reducing agent Na2SO3. The circular dichroism behavior analysis showed that the tertiary structure of the partially reduced lysozyme molecules became more flexible, leading to an obvious increase in the surface hydrophobicity and the tryptophan fluorescence intensity. Zeta potential analysis indicated that the introduction of SO32- led to a decrease in the surface charges of the reduced lysozyme molecules. Compared with the native lysozyme, the reduced lysozymes not only showed a 1 log increase in the antimicrobial activity against Escherichia coli ATCC 25922 and Salmonella enteritidis ATCC 13076 (P <0.05), but also maintained nearly the same antimicrobial activity against Staphylococcus aureus ATCC 29213 (P >0.05). Overall, the reductive modification with the food-friendly, compatible, and safe reducing agent Na2SO3 has broadened the antimicrobial action spectrum of the modified lysozymes against Gram-negative bacteria, with the enhancement extent depending on the reduction degree and the type of bacterial strains. The integrated results suggest that the Na2SO3-reduced lysozyme can be used as a novel safe potential bactericidal additive for food-processing industry.

This study investigated the effects of phosvitin (PV), one of the major proteins from egg yolk, with different degree of phosphorylation on the physiology of an osteoblast (MC3T3-E1) cell line. The proliferation and differentiation of MC3T3-E1 were analyzed using the CCK-8 and the alkaline phosphatase (ALP) assay, respectively. The effect of PV on the mineralization of MC3T3-E1 was monitored using the Alizarin-red staining. PV at 100 μg/mL increased the ALP activity by 145% of the control after 7 days of incubation. PV also stimulated the proliferation and differentiation of MC3T3-E1 in a phosphorylation level-dependent manner. The RT-PCR reactions indicated that PV stimulated the expression of BMP-2 and OPG mRNA in a phosphorylation-dependent manner, but inhibited RANKL mRNA expression in MC3T3-E1. This result suggested that the phosphate groups in PV not only stimulated the proliferation and differentiation of MC3T3-E1, but also controlled the mineralization by regulating the expression of BMP-2, RANKL and OPG mRNA in the osteoblast cell., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Phosphorylation of phosvitin has been proved to play an important role in the mineralization, but the active region of phosvitin is still not known yet. Four phosvitin phosphopeptides (PPPs) were obtained after separating from ion exchange column and desalting from gel filtration, and named as PPP0, PPP1, PPP3 and PPP4, respectively. The effect of PPP on the mineralization was investigated by pH-stat system, Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscope. SDS-PAGE and circular dichroism were applied to study the composition and the structure of PPP. Results showed that the order of promoting mineralization was as follows: PPP3 > phosvitin > PPP4 > PPP1 > control > PPP0. PPP0 and PPP1 was not involved in the mineralization, while the structure of PPP4 was too compact to promote mineralization because of its high β-sheet conformation. PPP3, which contained a 10 kDa peptide, is the most effective promoter for mineralization. LTQ-MS/MS results indicated that the phosphorylated serine clusters of phosvitin was the active region for promoting mineralization., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Immunoglobulin Y (IgY) is a new therapeutic antibody that exists in hen egg yolk. It is a glycoprotein, not much is known about its N-glycan structures, site occupancy and site-specific N-glycosylation. In this study, purified protein from hen egg yolk was identified as IgY based on SDS-PAGE and MALDI-TOF/TOF MS. N-glycan was released from IgY using peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine-amidase treatment, and the molecular weight of IgY was calculated using the difference between the molecular weight of IgY and deglycosylated IgY. Two potential N-Glycosylation sites (ASN 308 and ASN 409 ) were detected on IgY by nanoLC-ESI MS. Sugar chains were separated using normal phase liquid chromatography after fluorescence labeling, and 17 N-glycan structures were confirmed using ESI-MS. The sugar chain pattern contained high-mannose oligosaccharide, hybrid oligosaccharide and complex oligosaccharide. These results could lead to other important information regarding IgY glycosylation., (Copyright © 2017 Elsevier B.V. All rights reserved.)

It is important to detect lysozyme (LYZ) in a simple and rapid manner because of its potential application in the treatment of diseases and in the food industry. In this study, it was observed that the strong fluorescence of LYZ-modified Quantum Dots (QDs-LYZ) could be effectively quenched by gold nanoparticle(AuNPs) modified with antibodies against LYZ (anti-LYZ) due to fluorescence resonance energy transfer (FRET) between QDs-LYZ and anti-LYZ-AuNPs. The fluorescence can be reversibly recovered by LYZ (on state) owing to specific competitive interactions between LYZ, QDs-LYZ and anti-LYZ-AuNPs. The interaction of QDs-LYZ with anti-LYZ-AuNPs was studied by absorption, fluorescence spectroscopy and transmission electron microscopy (TEM). Under optimal conditions, LYZ can be detected with a linear range of 50-1000ng/mL and a detection limit (LOD) of 33.43ng/mL. This rapid and selective QD-based sensor was successfully applied for quantitation of LYZ in actual egg products. Furthermore, the strategy described in this report could be followed conveniently to establish similar immunosensors for the rapid detection of other proteins using corresponding antibodies., (Copyright © 2017 Elsevier B.V. All rights reserved.)

An efficient one-step grafting approach was developed to modify ovalbumin (OVA) by phosphorylation through selective reaction with the hydroxyl group of Ser and Thr residues present in OVA. The site-specific phosphorylated conjugates were characterized by Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF/MS) and the results indicated that the Ser residue could be more readily phosphorylated, and the typical phosphopeptides 264 LTEWTSSNVMEER 276 and 340 EVVGSAEAGVDAASVSEEFR 359 demonstrated the formation of monophosphoester. Moreover, 13 C NMR analysis showed that the βCH 2 of Ser acted as a hydroxyl donor to react with sodium tripolyphosphate (STPP), and the conjugates with variable phosphorylation sites could improve the weak network and the resulting poor mechanical properties of ovalbumin-based hydrogels. Furthermore, small-amplitude oscillatory measurements, creep recovery tests and texture profile analysis of hardness and stickiness indicated that phosphorylation can strengthen the intermolecular cross-linking of protein molecules and produce significant influence on the rheological behavior and texture properties, suggesting that a suitable conjugation site is essential for the best gelation properties at a different pH. The integrated results indicate that phosphorylation change significantly modify the viscoelastic and mechanical properties of OVA-based hydrogels by changing molecular dynamics upon heating., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Phosvitin is a unique highly phosphorylated protein that plays a role in the regulation of mineralization. This study investigated the role of phosphorylation of phosvitin in the phase transformation of calcium phosphate in the mineralization solution. Partially dephosphorylated phosvitins (T1, T2, T3 and T4) were prepared with 2.98, 19.46, 43.39 and 71.07% of phosphate released from native phosvitin, respectively. And their effect on regulating the phase transformation was investigated, the characterization and composition analysis was performed by circular dichroism, Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. Results showed that phosvitin in the acceleration effect of phase transformation was dose-concentration effect by pH-stat titration. With lower dephosphorylation degree of phosvitin (<20%), the acceleration effect was weaker than native phosvitin, since phosphorylation and random structure of phosvitin were reduced. However, with higher dephosphorylation degree of phosvitin (>40%), the acceleration effect was enhanced compared to native phosvitin, in which the β-sheet structure was increased and phosvitin was partially hydrolyzed to phosphopeptides. The acceleration effect of phase transformation was as follows: T4>T3>phosvitin>T1>T2> Control. This study clearly demonstrated that phosphorylation of phosvitin played an important role in the regulation of mineralization., (Copyright © 2017 Elsevier B.V. All rights reserved.)

To improve the interfacial properties, a phosphorylation modification of OVA was performed through dry-heating at three different pH values (5.0, 7.0 and 9.0) in the presence of sodium tripolyphosphate. X-ray photoelectron and Raman spectroscopies confirmed that phosphate groups were successfully grafted onto the ovalbumin backbone through covalent interaction to form OP bond. Additionally, 23, 21 and 18 phosphorylation sites were identified in the OVA that had been phosphorylated at pH 5.0, 7.0 and 9.0 (P-OVA5, P-OVA7 and P-OVA9) respectively by MALDI-TOF mass spectroscopy. More phosphorylated peptides and possible phosphorylation sites were found here than in previous studies with the reaction time reduced to 12h. As a result, the iso-electric point (pI) of P-OVA shifted to lower pH, improving the stability of the P-OVA-included system over a wider pH range. The dynamic interfacial tension, which depends on the phosphorylation-induced conformational change, was explored by Fourier-transform Raman and circular dichroism spectroscopies, and the equilibrium interfacial tension decreased from 17.359mNm -1 for natural OVA (N-OVA) to 15.969mNm -1 for P-OVA9. Furthermore, P-OVA was applied to O/W emulsions, resulting in a narrower size distribution with a smaller particle size in P-OVA-stabilized emulsions than in N-OVA-stabilized emulsions. The increase rate of mean particle diameter after 60-min storage decreased from 72.37% for N-OVA to 7.97% for P-OVA5, implying a significant improvement of emulsion stability by preventing aggregation and coalescence. The results from this work demonstrated that the natural biopolymer can be applied to O/W emulsions by enhancing interfacial properties with phosphorylation., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Immunoglobulin Y (IgY) is a new therapeutic antibody, and its applications in industry are very broad. To provide insight into the effects of N-glycosylation on IgY, its conformation and stability were studied. In this research, IgY was extracted from egg yolk and then digested by peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine-amidase. SDS-PAGE and infrared absorption spectrum showed that carbohydrates were distinctly reduced after enzymolysis. The circular dichroism spectrum indicated that the IgY molecule became more flexible and disordered after removal of N-glycan. The fluorescence intensity revealed that Trp residues were buried in a more hydrophobic environment after disposal of N-glycan. Storage stability decreased with the removal of oligosaccharide chains based on size-exclusion chromatography analysis. Deglycosylated IgY exhibited less resistance to guanidine hydrochloride-induced unfolding. After deglycosylation, IgY was more sensitive to pepsin. Therefore, N-glycosylation played an important role in the maintenance of the structure and stability of IgY., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Chicken IgY has been applied in the food industry as an important supplement. Glycation of IgY is of special interest due to its possible influence on the structure and functionality of IgY. IgY was subjected to in vitro glycation with 4 different monosaccharides, including glucose (Glu), mannose (Man), fucose (Fuc), and fructose (Fru). The objective of this paper was to characterize the formation of IgY-sugar conjugates using ultraviolet spectra, fluorescence spectra, circular dichroism spectra, Fourier transform infrared spectra, and SDS-PAGE and differential scanning calorimetry analysis. The antigen epitopes of native and glycated IgY was determined by enzyme-linked immunosorbent assay (ELISA). The existence of broad bands in stacking gel and sample well demonstrated that reducing monosaccharides covalently bound to IgY. The secondary structure of IgY was altered from a well-defined β-sheet structure to a random coil structure. Fluorescence spectra showed that IgY was more hydrophilic after glycation. Thermal stability of glycated IgY was remarkably increased over that of native IgY. However, ELISA results would suggest that the antigen epitopes recognized by the polyclonal antibody and overall conformation changed in the IgY molecule due to a decrease in polyclonal antibody binding to glycated IgY. Data suggested that glycation induced by reducing sugars significantly affects the structure and antigen-binding ability of IgY, which could reduce the utility of IgY in certain applications., (© 2016 Poultry Science Association Inc.)

The changes of lysozyme structure during egg storage were investigated by Fluorescence spectroscopy, Circular Dichroism spectroscopy and Fourier Transform-Raman spectroscopy, and the relationships between lysozyme properties (enzyme activity, emulsibility and foamability) and secondary structure were also discussed. During the storage, the percentages of α-helix and β-turn declined, conversely the β-sheet and random coil increased, the polarity of microenvironment around tryptophan residue gradually decreased. The results suggested that the conformation of lysozyme became more flexible during egg storage. Lysozyme activity was decreased but ESI and FA of lysozyme rose up with the storage duration. Correlation analysis revealed that second structure of lysozyme significantly affected lysozyme properties during egg storage. These findings would certainly be useful for further study of food storage and production., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This paper studies the metabolic pathway of sucrose in pullulan fermentation by Aureobasidium pullulans. Because of its high pullulan production, sucrose proved to be the best carbon source for pullulan synthesis by A. pullulans CGMCC1234 (36.3g/L). Compared to other carbon sources, A. pullulans cells reached the stationary phase more quickly in the presence of sucrose. The specific sugar types and concentrations occurring during pullulan fermentation were detected using High Performance Liquid Chromatography (HPLC). HPLC results revealed that sucrose did not simply break down into glucose and fructose in the medium employed. Kestose (22.69g/L) also accumulated during early stages of fermentation (24h), which reduced the osmotic pressure of the extracellular fluid and diminished the inhibition of cell growth and pullulan production. β-Fructofuranosidase activity strongly depended on the carbon source. Sucrose was the best inducer of β-fructofuranosidase production. However, β-fructofuranosidase production did not directly and/or proportionally correlate with the growth of A. pullulans cells., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Avidin is a glycoprotein with antinutritional property, which should be limited in daily food. We developed an affinity biosensor system based on resonance Rayleigh scattering (RRS) and using affinity biotin labeling Au nanoparticles (AuNPs). This method was selective and sensitive for quick avidin detection due to the avidin-biotin affinitive interaction. Under optimal conditions, RRS intensity of biotin-AuNPs increase linearly with an increasing concentration of avidin from 5 to 160 ng/mL. The lower limit of detection was 0.59 ng/mL. This rapid and selective avidin detection method was used in synthetic samples and egg products with recoveries of between 102.97 and 107.92%, thereby demonstrating the feasible and practical application of this assay., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Phosvitin is a unique highly phosphorylated protein that plays a role in the regulation of calcification. We conducted a comprehensive study of the chemical, thermodynamic and structural aspects of the interaction of phosvitin with calcium ions using a calcium ion selective electrode (ISE), isothermal titration calorimetry (ITC), circular dichroism spectrum (CD) and fluorescence spectroscopy, respectively. The results showed that under neutral and alkaline conditions, distinct high affinity and low affinity binding modes existed in the interaction between phosvitin and calcium. The high affinity association constant was approximately 10(4)mol(-1), while the binding sites contained nearly 30mol of calcium per mole of phosvitin. This reaction was driven by enthalpy. The unordered and β-turn conformations of phosvitin increased, while the β-sheet conformation decreased. The main interaction forces were electrostatic force, hydrogen bonds or van der Waals force. The low affinity association constant and binding sites were not constant, as many calcium ions were sequestered by phosvitin. The binding reaction was driven by entropy, and the β-sheet conformation of phosvitin increased while the unordered conformation decreased. The main interaction force was hydrophobic force. However, under acidic conditions, the interaction between phosvitin and calcium was an entropy-driven endothermic reaction, and the main interaction force was weak hydrophobic force. This calcium-binding characteristic of phosvitin may play a specific role in its biological function., (Copyright © 2016 Elsevier Inc. All rights reserved.)

A novel strategy for ovotransferrin (OVT) detection by tracing the "on-off-on" fluorescence signals of quantum dots (QDs) and gold nanoparticles (AuNPs) utilizing fluorescence measurements were established in this article. The immune interaction between QDs-OVT and anti-OVT-AuNPs leads to drastic quenching (turning off) of the donor by a fluorescence resonance energy transfer (FRET) process. After the addition of free OVT, anti-OVT-AuNPs peel off from the QDs-OVT surface and bind to free OVT due to competitive immunoreactions, resulting in the restoration of the fluorescence intensity of QDs (turning on). Consequently, this process can be utilized for the selective detection of OVT via optical responses. Under optimal conditions, the fluorescence intensity of the system increased linearly with increasing concentrations of OVT from 0.05 to 3.8 μg/mL. The limit of detection of OVT was 23.55 ng/mL. This method was applied to the analysis of OVT in egg powder samples. Furthermore, the strategy provided in this work could be conveniently followed to establish similar immunosensors for the rapid detection of other proteins with corresponding antibodies., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Egg white proteins provide essential nutrients and antimicrobial protection during embryonic development. Although various biological functions of major egg white proteins have been investigated via embryogenesis, understanding of global changes in low-abundance proteins has been limited. In the current study, a proteomic analysis of low-abundance egg white proteins was conducted using combinatorial peptide ligand libraries (CPLL), two-dimensional gel electrophoresis (2-DE), and matrix-assisted laser desorption/ionization-time-of-flight with two mass analyzers for tandem mass spectrometry (MALDI-TOF MS/MS) during the rapid embryonic growth period. Significant increases in the relative abundance of 88 protein spots (P ≤ 0.05), of which 47 spots were found to correspond to 10 proteins from 8 protein families were identified over 16 d incubation. During this developmental process, the protein concentration increased and the amount of albumin solid material decreased in the residual egg white. Clusterin precursors were observed over a wide range of pH values and the tenp protein increased continuously during embryonic development. Low-abundance proteins were identified in a comparison of optimal incubation conditions to the altered conditions of 2 control groups to better understand the function of these proteins in egg whites. Collectively, these findings provide insight into the supportive role of the egg white during embryonic development, enabling a broader understanding of chick embryogenesis., (© 2015 Poultry Science Association Inc.)

In this paper, we constructed the fluorescence resonance energy transfer (FRET) system between two multi-color quantum dots (QDs) of two sizes for rapid and sensitive detection of Staphylococcus aureus. In this system, green-emitting QDs conjugated with rabbit anti-S. aureus antibodies were used as energy donors while orange-emitting QDs conjugated with goat-anti-rabbit IgG were used as energy acceptors to form FRET system. Pre-binding of Staphylococcus aureus (S. aureus) on the donor occupied the binding sites and thus blocked resonance energy transfer between two colors QDs, leading to the quenching fluorescence of the acceptor. The fluorescence of acceptor has a linear calibration graph with the concentrations of S. aureus from 52 to 2.6×10(5) CFU mL(-1). The low detection limit was 10 CFU/mL. It was worth mentioning that the detection method of S. aureus had been applied to the analysis of apple juice and milk samples, which could potentially be developed into a sensor in the further study., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Chicken egg yolk immunoglobulin (IgY) is a superior alternative to mammalian immunoglobulin. However, the practical application of IgY in research, diagnostics, and functional food is limited due to complex or time-consuming purification procedures. The objective of this study was to develop a simple, safe, large-scale separation method for IgY from egg yolk. Egg yolk was diluted with 6-fold delipidation solutions made of different types (pectin, λ-carrageenan, carboxymethylcellulose, methylcellulose, and dextran sulfate) and concentrations (0.01, 0.05, 0.1, 0.15, and 0.2%) of polysaccharides, respectively. The yolk solution was adjusted to pH 5.0, and then kept overnight at 4°C before being centrifuged at 4°C. The resulting supernatant was added to 35% (w/v) (NH4)2SO4 and then centrifuged. The precipitant, which contained IgY, was dissolved in distilled water and then dialyzed. SDS-PAGE and Western blotting were utilized to conduct qualitative analysis of IgY; high-performance liquid chromatography (HPLC) was used for quantitative analysis. The immunoreactivity of IgY was measured by ELISA. The results showed that yield, purity, and immunoreactivity varied with types and concentrations of polysaccharides. The optimal isolation of IgY for pectin, λ-carrageenan, dextran sulfate, and carboxymethylcellulose was at the concentration of 0.1%; for methylcellulose, optimal isolation was at 0.15%. The best results were obtained in the presence of 0.1% pectin. In this condition, yield and purity can reach 8.36 mg/mL egg yolk and 83.3%, respectively, and the negative effect of IgY on immunoreactivity can be minimized. The procedure of isolation was simplified to 2 steps with a higher yield of IgY, avoiding energy- and time-consuming methods. Therefore, the isolation condition under study has a great potential for food industry production of IgY on a large scale., (© 2014 Poultry Science Association Inc.)

The aim of this study was to investigate the role of phosvitin in bone formation in chicken embryos. The yolk P content, P/N ratio and secondary structure of phosvitin, alkaline phosphatase (ALP) activity of the tibia, and body length were determined during incubation. A high correlation was found between the phosphate group content of phosvitin and both secondary structure and bone metabolism (ALP activity in the tibia, body length). The ALP activity and body length growth slightly lagged behind changes in the P/N ratio and the secondary structure of phosvitin. The phosphate content of phosvitin decreased, the γ-random coil and β-turn gradually transformed into α-helixes, and the secondary structure of protein tended to become more orderly; these changes mainly occurred on d 13 to 16. Bone formation of the chicken embryos occurred primarily on d 14 to 18, whereas ALP activity and body length growth increased substantially. The results indicate that phosvitin P is involved in chicken embryo bone formation through dephosphorylation., (©2014 Poultry Science Association Inc.)

The characteristic of Listeria monocytogenes' pyrolysis product was found by fingerprint analysis of high resolution pyrolysis gas chromatography and mass spectrometry (HRPGC/MS), which hold a great potential to rapidly detect L. monocytogenes with the application of selected ion monitoring (SIM). Food products (beef and milk) contaminated by L. monocytogenes and uncontaminated were evaluated. The retention time of the characteristic peak of pyrolysis product was 19.056min, the ion of m/z were 54, 98. The results showed that the peak at retention time 19.056min was detected in agricultural products that contaminated by L. monocytogenes, while the result of the uncontaminated food, there is no peak at the retention time 19.056min. Qualified by the retention time of chromatographic and mass spectrometry, it can eliminate the interference induced by different types of agricultural products. The results prove united technologies of HRPGC/MS and SIM is not only reliable, reproducible, but also a new method for rapid detecting L. monocytogenes in food products., (Copyright © 2014. Published by Elsevier B.V.)

Metal-protein interaction for regulating the function and structure of proteins is of major interest. We demonstrate here that the addition of 9 μmol Mg2+ per mg ovomucin resulted in a 2.0-fold increase in the adhesion capacity of ovomucin to New Disease Virus (NDV) using ELISA method. The hemagglutinin inhibition rate of 100 μg/mL ovomucin-Mg2+ mixture (9 μmol Mg2+ per mg ovomucin) to NDV increased to 55.61%, which is significantly higher than that of the pure ovomucin (P<0.01). Binding characteristics of ovomucin to Mg2+ were then evident by fluorescence and FT-IR spectroscopy as well as dynamic light scattering (DLS) technology. Fluorescence and FT-IR spectroscopy results suggest that Mg2+ prefers to interact with the carbohydrate moiety of ovomucin without significant changes in the secondary structure when Mg2+ concentration is less than 9 μmol/mg ovomucin. When Mg2+ increases to 16 μmol/mg ovomucin, it gives rise to changes in secondary structure, and forms a more compact configuration. This is supported by the hydrodynamic radius of ovomucin with and without Mg2+ binding as examined by DLS. The Mg2+ bound in regulating the structure and activity of ovomucin provided important insight into the effect of metal ions on ovomucin binding to pathogens., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Little is known regarding the diversification of relative low-abundance proteins in hen egg white that underlie the process of chicken embryonic development. The purpose of this study was to identify changes that may be involved in the development of chick embryos. Comparative proteomic analysis was conducive to revealing the potential biological function of low-abundance proteins and embryonic development demand. In addition, those proteins that are increased in abundance seem to have advantages to be targeted as new biomarkers for animal disease or animal production. However, the huge disparity in abundance in chicken egg white and poor performance of affinity depletion methods were specific challenges. This study applied combinatorial peptide ligand library for expanding the deep proteomics. Two-dimensional gel electrophoresis (2-DE) was performed with the hen embryo egg white, which was obtained from embryos at d 0 and 7. The protein spots showing significant increases were selected for identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry/mass spectrometry (2 mass analyzers for tandem mass spectrometry). Many precursors were identified as strongly increased after 7 d of incubation. They were ovoinhibitor precursor, clusterin precursor, apolipoprotein D precursor, and extracellular fatty acid-binding protein precursor. Moreover, clusterin precursor were observed concentrated in 2 regions: one is the range of molecular weight increase and the other is the range of high pH. In addition, ovalbumin and ovotransferrin were observed in high pH area in a 2-DE map. These findings will give insight into the changes in fertilized egg white proteins during hatching and provide a better understanding of the biochemical changes in the egg development process.

The egg white protein alterations during the early phase of chicken embryonic development were recently reported by our laboratory. Nevertheless, the original albumen differences between fresh unfertilized and fertilized chicken eggs have not been investigated. By using 2-dimensional gel electrophoresis (2-DE), coupled with matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF MS/MS) method, 1 ovalbumin protein spot as well as 6 ovalbumin-related protein Y spots were identified showing more than 10-fold differences (P < 0.01) in abundance between fresh unfertilized and fertilized chicken egg whites. Six of these protein spots represented higher intensity in fertilized eggs through 2-DE analysis. It was thus concluded that ovalbumin protein family, especially ovalbumin-related protein Y, may play an important role in embryonic development, which still needs to be validated. This finding will provide insight into embryogenesis to improve our understanding of the functions of ovalbumin family proteins in regulating or supporting embryonic development.

Water-soluble and high luminescent l-glutathione-capped-ZnSe quantum dots (QDs) were applied for ultrasensitive Pb(II) detection. l-glutathione-capped-ZnSe QDs were synthesized by a facile colloid aqueous phase route. It is characterized by transmission electron microscopy, X-ray powder diffraction spectrometry, Fourier transform infrared spectrometry, Ultraviolet-visible spectrometry and fluorescence spectrometry. Quantum yields of l-glutathione-capped-ZnSe QDs could reach 50.1% without post irradiation. The fluorescence quenching of the l-glutathione-capped-ZnSe QDs depended on the concentration, pH and reaction time of the Pb(II) solution. The possible mechanism of fluorescence of l-glutathione-capped-ZnSe QDs quenched by Pb(II) was discussed in detail. Under optimal conditions, the quenched fluorescence intensity increased linearly with the concentration of Pb(II) in the range of 1.0×10(-8)∼8.0×10(-7)mol/L. The limit of detection for Pb(II) was 0.71 nmol/L. This developed method is demonstrated to contain improved sensitive and selective characteristics for the detection of trace Pb(II) in water., (Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.)

The avidin-biotin interaction was evaluated systematically by fluorescence spectroscopy under different conditions of temperature, pressure, pH, metal ions, incubation time and initial avidin concentration. The binding constant was calculated according to the modified Stern-Volmer equation, which deduced the existence of static quenching mechanism. The data obtained revealed that avidin-biotin interaction exhibited temperature, pH, metal ions, incubation time and initial avidin concentration sensitivity. The binding constants decreased with increase in temperature, while the binding sites were independent of temperature. The values of thermodynamic parameter ΔH (-149.85 kJ mol(-1)) and ΔS (-284.26 J mol(-1) K(-1)) suggested hydrogen bonds and van der Waals played a major role in the reaction. The binding constants between avidin and biotin increased firstly and then decreased gradually with the increase of pH values. Metal ions can also affected the binding constants between avidin and biotin. The association kinetics firstly acquired by the combination of the change in fluorescence per unit time and the modified Stern-Volmer equation indicated that the reaction time required to reach equilibrium was 2200 s, and the average reaction rate for the binding process was very high in the first 180 s. Reaction of the avidin in the first 180 s was more than 40% of the total avidin involved in the whole process., (Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.)

Avian egg albumen participates in embryonic development by providing essential nutrients as well as antimicrobial protection. Although various biological functions of egg white proteins were suggested during embryogenesis, global changes of these proteins under incubation conditions remained uninvestigated. This study presents a proteomic analysis on the change of egg white proteins during the first week of embryonic development. By using 2-DE, together with MALDI-TOF MS/MS, thirty protein spots representing eight proteins were identified showing significant changes in abundance during incubation. An accelerating degradation of ovalbumin was observed in a wide range of molecular weight. In addition, four protein complexes were predicted according to the detected molecular weight increase. Among these speculated protein complexes, an ovalbumin spot coupled with RNA-binding protein was detected. The absence of these protein complexes before incubation, followed by the constant increase in abundance during incubation indicates conceivable pivotal roles in embryonic development. To better understand the function of the proteins identified in this study, discrepancies of egg white protein changes between fertilized and unfertilized chicken eggs were additionally demonstrated. These findings will provide insight into the embryogenesis process to improve our knowledge of egg white proteins in regulating and supporting early embryonic development., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Purification of ovomucin is still an empirical technique and sometimes insufficient quantities of ovomucin are purified to allow characterization. Here we aimed to investigate the effect of MgCl(2) on the purity and bioactivity of ovomucin during isoelectric precipitation process and to develop an effective protocol to prepare pure ovomucin with high bioactivity. It was found that addition of MgCl(2) is an alternative approach to remove lysozyme from ovomucin, and that the hemagglutination inhibition (HI) activity of ovomucin with MgCl(2) against New Disease Virus (NDV) was about two times higher than the protein without salts. Thus, an improved procedure comprises a precipitation with 0.05 mol/L CaCl(2) followed by precipitation with 0.05 mol/L MgCl(2) was developed for the isolation of ovomucin. Better adhesion property of ovomucin was observed when low concentration of MgCl(2) was added in the designed ELASA test, whereas the adhesion property of the pure ovomucin without salts to NDV was lower. Thus, magnesium (II) plays an important role in the activity of ovomucin, and the alternative method developed in this study may significantly facilitate the further research on the mechanism of ovomucin activity., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Knowing the adsorption behavior of target proteins on biofunctional magnetic nanoparticles is of great importance for the separation and purification of proteins. Adsorption behaviors of avidin on biofunctional magnetic nanoparticles binding to iminobiotin were investigated under different conditions of temperature, pH, ionic strength, and feed avidin concentration. Biofunctionalization of the non-functional nanoparticles was performed, coupled with iminobiotin. Characterization of the particles was carried out using transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The results showed the avidin adsorption behaviors were mainly dependent on affinity interaction between avidin and iminobiotin coupled with the nanoparticles, which exhibited temperature, pH, ionic strength, and feed avidin concentration sensitivity. Maximum avidin adsorption capacity was achieved as 225 mg avidin/g biofunctional nanoparticles. Results were well fitted to the Langmuir isotherm model with the feed avidin concentration of less than 45 μg/ml. Based on the experiments above, the biofunctional magnetic nanoparticles were used to separate avidin from treated egg-white solution containing large amounts of other proteins. The avidin was isolated in 92% yield with an optical purity of more than 98.5% according to the HPSEC data. The regeneration of these nanoparticles was also studied and almost 87.3% of avidin could still be recovered by these regenerated nanoparticles., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A new method for determination of lysozyme with high sensitivity based on Resonance Rayleigh scattering (RRS) by using Au nanoparticles as a probe was proposed in this experiment. The RRS spectrum, nonlinear scattering (second-order scattering (SOS), frequency doubling scattering (FDS)) spectra and absorption spectrum of the Au nanoparticles-lysozyme system have been analyzed. In addition, the effects of several factors on scattering intensities were investigated, including pH value of solution, amount of Au nanoparticles, mixing sequence of each reagent and the coexisting substances. The results showed that the coexisting substances have little influence on the RRS intensities of the systems. Moreover, the possible mechanism for the RRS enhancement of Au nanoparticles-lysozyme system was preliminary discussed. The RRS method for determination of lysozyme has good sensitivity and selectivity with the detection limits 30.1 ng/ml. The contents of lysozyme were determined with recoveries of 98.2-105.4% and relativity relative standard deviation (RSD) of 0.3-3.7%, respectively. It proved that the method established in our study is suitable for the determination of lysozyme in synthetic sample and natural chicken egg white sample., (Copyright © 2011 Elsevier B.V. All rights reserved.)