Alpha-to-beta structural transformation of ovalbumin: heat and pH effects

Selective Hydrolysis of Ovalbumin by Zr-Based Lacunary Polyoxotungstate in Surfactant Solutions

This study aims to design an artificial metalloprotease based on a Zr-containing polyoxometalate Na8[Zr(W5O18)2] [Zr(W5)2] for the hydrolysis of ovalbumin (OVA) in the presence of different surfactants, which can be used in many areas of the biological and medical sciences, particularly for targeted proteolytic drug design. For this reason, parameters, including the free energy of binding, the chemical nature of amino acid residues, secondary structures, and electrostatic potentials, of Zr(W5)2-OVA and Zr(W5)2-OVA-surfactant were analyzed by molecular docking simulations. The investigations showed that the presence of surfactants decreases the binding affinity of Zr(W5)2 for OVA amino acids, and hydrogen bonds and van der Waals interactions are formed between Zr(W5)2 and OVA amino acids. Additionally, GROMACS further illustrated the significance of SDS and CTAB surfactants in influencing the conformational changes of the OVA that lead to selective protein hydrolysis. In agreement with molecular dynamics simulation results, the experimental analysis showed more protein hydrolysis for the Zr(W5)2-OVA-surfactant systems. For instance, circular dichroism spectroscopy indicated that Zr(W5)2-OVA-CTAB and Zr(W5)2-OVA-TX-100 were more hydrolytically efficient due to the increased level of β-structures rather than α-chains, which showed that surfactants can facilitate the accessibility of Zr(W5)2 to the cleavage sites by inducing partial unfolding of the OVA structure.

Effect of Protein Surface Hydrophobicity and Surface Amines on Soy Adhesive Strength

Soy is considered one of the most promising natural materials for manufacturing wood adhesives due to its low cost, high protein content, and ready availability. However, more cost-effective ways of improving its wet shear strength are needed to achieve wider market acceptance. Protein adhesive wet strength depends on the use of (typically expensive) crosslinking additives as well as the processing/denaturation of the protein. It has been commonly stated in the literature that protein denaturation leads to higher bond strength by activating the surface and exposing the reactive groups. Therefore, we investigated how differences in surface reactive groups (surface hydrophobicity and reactive amine groups) brought on with different denaturation treatments relate to bonding performance. Fourteen soy protein isolates (SPIs) with different denaturation histories were investigated. Characterization of the SPIs included surface hydrophobicity, surface amine content, extent of protein hydrolysis, and bond strength (wet and dry, with and without polyamidoamine epichlorohydrin (PAE) crosslinking agent) by ASTM D7998. The molecular weight patterns showed that proteins denatured by extensive hydrolysis had very low bond strengths. Adding the crosslinker, PAE, improved all the shear strength values. We found that the number of water-accessible reactive amine groups on protein surfaces had no impact on the adhesive strength, even with the amine-reactive crosslinker, PAE. Conversely, increased surface hydrophobicity was beneficial to adhesive strength in all cases, though this correlation was only statistically significant for wet strength without PAE. While, in general, denatured proteins are typically thought to form better bonds than native state proteins, this work suggests that it matters how proteins are denatured, and what surfaces become exposed. Denaturation by hydrolysis did not improve bond strength, and extensive hydrolysis seemed highly detrimental. Moreover, exposing hydrophobic surface groups was beneficial, but exposing covalent bond-forming reactive amine groups was not.

Unleashing the binding interaction of chrysin-Cu(II) complex with the biomacromolecular targets: further studies of cell cytotoxicity and radical scavenging properties

Flavonoids are significant dietary components and have ability to coordinate with metal ions to produce novel drug discovery leads that are superior to those of the parent flavonoids. Here, in this report, we have synthesized chrysin-Cu(II) complex (as per reported article) and characterized it further with different analytical techniques. The synthesized complex was evaluated for radical scavenging and cell cytotoxicity studies where it exhibited enhanced activity as compared to bare chrysin. The interaction studies of the complex with ct-DNA (Kb ⁓ 105 M-1), human serum albumin (HSA) and ovalbumin (Kb ⁓ 104 M-1) were evaluated using multi-spectroscopic and molecular docking studies. Groove binding mode with ct-DNA was observed as confirmed from competitive displacement studies, viscosity measurement, melting temperature estimation and docking analyses. The complex exhibited comparatively higher affinity towards ct-DNA which indicated it efficient transportation by the carrier proteins and controlled release in the target DNA.Communicated by Ramaswamy H. Sarma.

Spectroscopic Characterization of the Binding and Release of Hydrophilic, Hydrophobic and Amphiphilic Molecules from Ovalbumin Supramolecular Hydrogels

Protein-based hydrogels have attracted growing attention for pharmaceutical and biomedical applications. Ovalbumin (OVA), the hen egg white albumin, possessing good foaming and gelling properties and being widely used in the food industry, has recently been indicated as a potential pharmaceutical vehicle. In this study, the binding and release properties of pure OVA hydrogels were investigated by electron paramagnetic resonance (EPR) spin labeling. The comparative analysis between OVA and serum albumin (SA) hydrogels revealed the same release kinetics of hydrophilic 3-carbamoyl-proxyl and 3-carboxy-proxyl, suggesting the diffusion-dominated release of small probes from both hydrogel types. The results obtained with the amphiphilic 16-doxylstearate (16-DS) indicate that OVA, unlike SAs, does not possess a specific fatty acid binding site. However, the OVA hydrogels were able to accommodate a two-fold excess of 16-DS, resulting from protein thermally induced conformational changes, as confirmed by Raman spectroscopy. Similarly, the hydrophobic modified paullone ligand HL, which was initially free in the OVA solution, was bound in the hydrogel. The hydrogels were found to retain a significant amount of 16-DS and HL after 7-day dialysis in physiological saline. The observed facilitated binding of amphiphilic/hydrophobic molecules in OVA hydrogels compared to the solution, and their sustained release, demonstrate the applicability of OVA hydrogels in pharmaceutics.

Use of Dynamic Shear Rheology to Understand Soy Protein Dispersion Properties

Soy flour dispersions are used as adhesives for bonding interior wood laminates, but the high viscosity of these dispersions requires low solids in the adhesive formulations; the greater water content causes excessive steam pressure during hot press manufacturing. This limits the utility of soy adhesives in replacing urea-formaldehyde adhesives; thus, understanding the cause of high soy viscosities is important. Lack of literature on aqueous soy flour dispersion rheology led to our dynamic rheology studies of these dispersions to understand high viscosity and the effect of various additives. Even at low soy solids, the elastic nature outweighs the viscous properties at low shear, although increasing the shear results in shear-thinning behavior after the yield point. At even higher shear, beyond the flow point where the storage and loss moduli cross, some of the dispersions show an additional shear thinning transition. The comparison of the rheological properties of aqueous dispersions of the soy flour and protein isolate, and another natural protein, ovalbumin from egg whites, led to a better understanding of different types of rheological behaviors. The experimental observations of two observed shear thinning events for soy are consistent with the model of dispersed particles, forming clusters that then form large scale flocculants.

Deciphering the interactions of phytochemicals with ovalbumin, the major food allergen from egg white: spectroscopic and computational studies

Ovalbumin (OVA), the major component of egg white, has been used as a model carrier protein to study the interaction of four bioactive phytochemicals 6-hydroxyflavone, chrysin, naringin, and naringenin. A static quenching mechanism was primarily associated with the complexation of the flavonoids with OVA. Hydrophobic forces play a major part in the stability of the complexes. The structural changes within the protein in response to flavonoid binding revealed a decrease in OVA's α-helical content. The hypothesized binding site for flavonoids in OVA overlaps with one or more immunoglobulin E-binding epitopes that may have some effect in the immunoglobulin E response pathway. The flavonoids remain in the same binding site throughout the simulation time and impart protein stability by forming different noncovalent interactions. This study presents comprehensive information about the interaction of the flavonoids with OVA and the associated structural variations after the binding, which might help researchers better comprehend similar medication pharmacodynamics and provide critical information for future therapeutic development.

Multimodality imaging of nanoparticle-based vaccines: Shedding light on immunology

In recent years, there have been significant innovations in the development of nanoparticle-based vaccines and vaccine delivery systems. For the purposes of both design and evaluation, these nanovaccines are imaged using the wealth of understanding established around medical imaging of nanomaterials. An important insight to the advancement of the field of nanovaccines can be given by an analysis of the design rationale of an imaging platform, as well as the significance of the information provided by imaging. Nanovaccine imaging strategies can be categorized by the imaging modality leveraged, but it is also worth understanding the superiority or convenience of a given modality over others in a given context of a particular nanovaccine. The most important imaging modalities in this endeavor are optical imaging including near-infrared fluorescence imaging (NIRF), emission tomography methods such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) with or without computed tomography (CT) or magnetic resonance (MR), the emerging magnetic particle imaging (MPI), and finally, multimodal applications of imaging which include molecular imaging with magnetic resonance imaging (MRI) and photoacoustic (PA) imaging. One finds that each of these modalities has strengths and weaknesses, but optical and PET imaging tend, in this context, to be currently the most accessible, convenient, and informative modalities. Nevertheless, an important principle is that there is not a one-size-fits-all solution, and that the specific nanovaccine in question must be compatible with a particular imaging modality. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Performance of allergen testing in a survey of frozen meals and meals ready-to-eat (MREs)

A 7-plex immunoassay capable of detecting cashew, egg, hazelnut, milk, peanut, shrimp, and soy allergens was used to screen meals ready-to-eat (MREs) and frozen meals that contained meat or poultry. The same food matrices were also evaluated using single individual allergen immunoassays. Multiplex and single allergen test results were compared with the allergen declared on the food label, which was considered the standard. For both the frozen meals (n = 113) and MREs (n = 24) each analytical method failed to detect allergens that were declared on product labels, but only in frozen meals were allergens detected that were not declared on the label. Undeclared allergens were detected for egg in 1.8% (2/113) and for soy in 7.1% (8/113) of frozen meals. Labelled allergens were not detected in 0.9% (1/113) of milk, 4.4% (5/113) of egg, and 15% (17/113) of soy allergens in frozen meals. Assay performance for evaluating allergens in MREs was poor.

Restricted epitope specificity determined by variable region germline segment pairing in rodent antibody repertoires

Antibodies from B-cell clonal lineages share sequence and structural properties as well as epitope specificity. Clonally unrelated antibodies can similarly share sequence and specificity properties and are said to be convergent. Convergent antibody responses against several antigens have been described in humans and mice and include different classes of shared sequence features. In particular, some antigens and epitopes can induce convergent responses of clonally unrelated antibodies with restricted heavy (V_H) and light (V_L) chain variable region germline segment usage without similarity in the heavy chain third complementarity-determining region (CDR H3), a critical specificity determinant. Whether these V germline segment-restricted responses reflect a general epitope specificity restriction of antibodies with shared V_H/V_L pairing is not known. Here, we investigated this question by determining patterns of antigen binding competition between clonally unrelated antigen-specific rat antibodies from paired-chain deep sequencing datasets selected based solely on V_H/V_L pairing. We found that antibodies with shared V_H/V_L germline segment pairings but divergent CDR H3 sequences almost invariably have restricted epitope specificity indicated by shared binding competition patterns. This epitope restriction included 82 of 85 clonally unrelated antibodies with 13 different V_H/V_L pairings binding in 8 epitope groups in 2 antigens. The corollary that antibodies with shared V_H/V_L pairing and epitope-restricted binding can accommodate widely divergent CDR H3 sequences was confirmed by in vitro selection of variants of anti-human epidermal growth factor receptor 2 antibodies known to mediate critical antigen interactions through CDR H3. Our results show that restricted epitope specificity determined by V_H/V_L germline segment pairing is a general property of rodent antigen-specific antibodies.

Structural and proteomic analyses of vitelline membrane proteins of blackbird (Turdus merula) and song thrush (Turdus philomelos)

In this study, we aimed to perform structural and proteomic analysis of the vitelline membrane (VM) of two species birds belonging to the family Turdidae: blackbird (Turdus merula) and song thrush (Turdus philomelos). We performed structural analyses using scanning electron microscopy. The VM proteins were identified and compared to the best-known chicken VM proteins. According to our results, VM of both species has a typical three-layered structure: the outer layer, inner layer, and the continuous membrane between them. An unusual observation was the finding of “convexity” formed by the inner layer in blackbird. The role of these convex structures is not known, but they can be typical for the species and can be used in their identification. In addition, we identified two proteins in the VM of both species of birds, of which U3KEZ1 FICAL was not previously identified in any other bird species, and the U3JXV8 FICAL protein was confirmed only once in cockatiel parrot VM. The function of these proteins is not exactly known, but their structure shows similarities to the SERPIN proteins that are involved in microbiological defense, i.e., they are immune proteins. This study contributes to the current knowledge about the structure and composition of proteins of VM, especially because similar analyses have never been performed for Turdidae family. Knowledge of the structure and specific proteins of blackbird and song thrush VM can be beneficial in research on ecology and bird biology and also helpful in developing noninvasive and nongenetic identification methods.

Serum protein-based nanoparticles for cancer diagnosis and treatment

Serum protein as naturally essential biomacromolecules has recently emerged as a versatile carrier for diagnostic and therapeutic drug delivery for cancer nanomedicine with superior biocompatibility, improved pharmacokinetics and enhanced targeting capacity. A variety of serum proteins have been utilized for drug delivery, mainly including albumin, ferritin/apoferritin, transferrin, low-density lipoprotein, high-density lipoprotein and hemoglobin. As evidenced by the success of paclitaxel-bound albumin nanoparticles (Abraxane^TM), serum protein-based nanoparticles have gained attractive attentions for precise biological design and potential clinical application. In this review, we summarize the general design strategies, targeting mechanisms and recent development of serum protein-based nanoparticles in the field of cancer nanomedicine. Moreover, we also concisely specify the current challenges to be addressed for a bright future of serum protein-based nanomedicines.

Exploring the potential of infrared spectroscopy in qualitative and quantitative monitoring of ovalbumin amyloid fibrillation

Amyloid fibrils are highly ordered self-assembled (poly)peptide aggregates with cross-β structural pattern. Ovalbumin was used as a model for exploring the potential of infrared spectroscopy in detecting structural transitions and quantitative monitoring of amyloid fibrillation. Low pH (pH 2) and high temperature (90 °C) over the course of 24 h were conditions applied for amyloid formation. Fibrillation of ovalbumin was monitored by ThT and ANS fluorescence, and SDS PAGE. A significant increase in ThT fluorescence with a plateau reached after 4 h of incubation, without the lag phase, was detected. Structural transitions leading to amyloid fibrillation were analysed using all three Amide regions in ATR-FTIR spectra. Significant changes were detected in Amide I and Amide III region (decrease of α-helix and increase of β-sheet peaks). To establish a fast, precise and simple method for quantitative monitoring of amyloid fibrillation, the Amide I/Amide II ratios of aggregation specific β-sheets (1625 and 1695 cm^-1, respectively) with 1540 cm^-1 as internal standard were used, resulting in good correlation (R² = 0.93 and 0.95) with the data observed by monitoring ThT fluorescence. On the other hand, assessing aggregation specific β-sheet contents by self-deconvolution showed lower correlation with ThT fluorescence (R² = 0.75 and 0.64). Here we examined structural transitions during ovalbumin fibrillation in a qualitative and quantitative manner by exploiting the full potential of Amide regions simultaneously. Secondary structure distribution was monitored using second derivative spectra in Amide I region. A novel, simple mathematical calculation for quantitative monitoring of fibrils formation was presented employing that the increase in low and high frequency aggregation specific β-sheet in Amide I region compared to the internal standard in Amide II region is suitable for fibril formation monitoring.

A review on versatile applications of blends and composites of CNC with natural and synthetic polymers with mathematical modeling

Cellulose is world's most abundant, renewable and recyclable polysaccharide on earth. Cellulose is composed of both amorphous and crystalline regions. Cellulose nanocrystals (CNCs) are extracted from crystalline region of cellulose. The most attractive feature of CNC is that it can be used as nanofiller to reinforce several synthetic and natural polymers. In this article, a comprehensive overview of modification of several natural and synthetic polymers using CNCs as reinforcer in respective polymer matrix is given. The immense activities of CNCs are successfully utilized to enhance the mechanical properties and to broaden the field of application of respective polymer. All the technical scientific issues have been discussed highlighting the recent advancement in biomedical and packaging field.

A New Functional Model for Prediction of Chaperone Activity of the Recombinant M. tb Acr (α-Crystallin) Using Insulin as Substrate

Mycobacterium tuberculosis Acr is an important protein expressed in latent tuberculosis which is active as an oligomer in preventing misfolding of cellular proteins. In this study, Mycobacterium alpha crystallin (acr) gene was cloned and expressed in Escherichia coli (E. coli). The recombinant Acr protein was purified by Nickel-NTA resin. The oligomeric state of Acr was confirmed by gel filtration chromatography using Sephacryl S-200 and Native-PAGE. Studies of chaperone activity were performed with insulin as a substrate at different mole ratios of Acr with 2 types of samples, His tag elutes (H) and His tag elutes with gel filtration (G). It was observed that the ratio of different sizes of oligomers (9 to 24 mers) had a significant effect on chaperone activity. Using the mole ratio of Acr for both (H) and (G) samples to insulin B chain and ratio of oligomers, we determined the number of Acr molecules binding to insulin as a model substrate. We found that if 1.5% of the insulin B chains are covered completely by the (G) samples, aggregation is completely inhibited as compared to 6% with (H) samples. Pre-heat treatment studies were carried out at 37°C, 60°C, and 70°C. Far-ultraviolet Circular Dichroism (UV-CD) analysis provided fresh insights into the role of β-sheets and α-helices in chaperone activity, particularly in (H) samples suggesting a reversible conformational transition from helices to sheets. This enabled us to formulate a functional model for binding of Acr to insulin B chains which incorporated 4 types of secondary structure molecules. This might be a useful tool for analyzing in vitro preparations of recombinant Acr and build more consensuses on the structure-activity relationship especially in terms of oligomeric ratios.

Cyclodextrin/chitosan nanoparticles for oral ovalbumin delivery: Preparation, characterization and intestinal mucosal immunity in mice

A novel oral protein delivery system with enhanced intestinal penetration and improved antigen stability based on chitosan (CS) nanoparticles and antigen-cyclodextrin (CD) inclusion complex was prepared by a precipitation/coacervation method. Ovalbumin (OVA) as a model antigen was firstly encapsulated by cyclodextrin, either β-cyclodextrin (β-CD) or carboxymethyl-hydroxypropyl-β-cyclodextrin (CM-HP-β-CD) and formed OVA-CD inclusion complexes, which were then loaded to chitosan nanoparticles to form OVA loaded β-CD/CS or CM-HP-β-CD/CS nanoparticles with uniform particle size (836.3 and 779.2 nm, respectively) and improved OVA loading efficiency (27.6% and 20.4%, respectively). In vitro drug release studies mimicking oral delivery condition of OVA loaded CD/CS nanoparticles showed low initial releases at pH 1.2 for 2 h less than 3.0% and a delayed release which was below to 30% at pH 6.8 for further 72 h. More importantly, after oral administration of OVA loaded β-CD/CS nanoparticles to Balb/c mice, OVA-specific sIgA levels in jejunum of OVA loaded β-CD/CS nanoparticles were 3.6-fold and 1.9-fold higher than that of OVA solution and OVA loaded chitosan nanoparticles, respectively. In vivo evaluation results showed that OVA loaded CD/CS nanoparticles could enhance its efficacy for inducing intestinal mucosal immune response. In conclusion, our data suggested that CD/CS nanoparticles could serve as a promising antigen-delivery system for oral vaccination.

Impact of change of matrix crystallinity and polymorphism on ovalbumin release from lipid-based implants

The objectives of this study were to prepare lipid-based implants by hot melt extrusion (HME) for the prolonged release of ovalbumin (OVA), and to relate protein release to crystallinity and polymorphic changes of the lipid matrix. Two lipids, glycerol tristearate and hydrogenated palm oil, with different composition and degree of crystallinity were studied. Solid OVA was dispersed within the lipid matrixes, which preserved its stability during extrusion. This was partially attributed to a protective effect of the lipidic matrix. The incorporation of OVA decreased the mechanical strength of the implants prepared with the more crystalline matrix, glycerol tristearate, whereas it remained comparable for the hydrogenated palm oil because of stronger physical and non-covalent interactions between the protein and this lipid. This was also the reason for the faster release of OVA from the glycerol tristearate matrix when compared to the hydrogenated palm oil (8 vs. 28 weeks). Curing induced and increased crystallinity, and changes in the release rate, especially for the more crystalline matrix. In this case, both an increase and a decrease in release, were observed depending on the tempering condition. Curing at higher temperatures induced a melt-mediated crystallization and solid state transformation of the glycerol tristearate matrix and led to rearrangements of the inner structure with the formation of larger pores, which accelerated the release. In contrast, changes in the hydrogenated palm oil under the same curing conditions were less noticeable leading to a more robust formulation, because of less polymorphic changes over time. This study helps to understand the effect of lipid matrix composition and crystallinity degree on the performance of protein-loaded implants, and to establish criteria for the selection of a lipid carrier depending on the release profile desired.

Albumin-Mediated Biomineralization of Shape-Controllable and Biocompatible Ceria Nanomaterials

Although ceria-based nanostructures have emerged as fascinating materials with diverse biological activities, developing a facile, rapid, and biocompatible method of their preparation remains a major challenge. Herein we describe bovine serum albumin (BSA) protein-directed synthesis of ceria-based nanostructures, including ceria nanoclusters (CNLs), nanoparticles (CNPs), and nanochains (CNHs). Their preparation is simple, one-pot, and performed in a mild reaction condition with a "green" synthetic approach. Most importantly, these three kinds of ceria-based nanostructures can be synthesized in a shape and size controllable manner by tuning the reaction time, temperature, and molar ratio. The formation mechanism shows that growth of these ceria nanostructures is mediated by Ce³⁺/Ce⁴⁺ switchable redox system, reducible disulfide bonds, and unique spatial structures in albumin proteins. More importantly, these albumin-based ceria nanostructures exhibit high superoxide dismutase (SOD) mimetic activity and good biocompatibility, providing a promising prospect in biomedical application.

pH and heat induced structural changes of chicken ovalbumin in relation with antigenic properties

Ovalbumin is the major egg white protein known to induce allergic reactions in humans. A comprehensive evaluation of the structural and antigenicity features of ovalbumin subjected to different pH and heat treatments was performed by combining fluorescence spectroscopic measurements, ELISA and in silico prediction. The intrinsic fluorescence spectra indicated modification of the ovalbumin tertiary structure depending on pH and applied temperature. The heat treatment caused the alteration of ovalbumin structure, which exhibited gradual hydrophobic exposure. The in depths check of ovalbumin molecular model, after performing molecular dynamics simulations, indicated the slight transition toward a typical β-strand dominant structure with the temperature increase. Moreover the immunoenzymatic test was employed to estimate the effect of the pH and thermal treatment on the stability of ovalbumin epitopes. Only a 5.5% reduction of the residual antigenicity was observed when heat treating the ovalbumin samples at pH 7.0, whereas a significant reduction (over 82%) of the antigenicity was obtained at pH 9.5 and temperatures over 80°C. Both pH and thermal treatment affected the conformation of ovalbumin. The reduced recognition of the modified native ovalbumin by specific antibodies at alkaline pH is most probably a consequence of significant changes in the local conformation of the epitopes.

Protein-Nanoreactor-Assisted Synthesis of Semiconductor Nanocrystals for Efficient Cancer Theranostics

Transition metal sulfide nanocrystals are developed as a theranostic platform through the protein-nanoreactor approach with facile functionalization for multimodal NIRF/PA/SPECT/CT imaging and photothermal tumor ablation.

A Spectroscopy Approach for the Study of the Interaction of Oxovanadium(IV)-Salen Complexes with Proteins

Oxovanadium(IV)-salen complexes bind with bovine serum albumin (BSA) and ovalbumin (OVA) strongly with binding constant in the range 10(4)-10(7) M(-1) at physiological pH (7.4) confirmed using UV-visible absorption, fluorescence spectral and circular dichroism (CD) study. CD results show that the binding of oxovanadium(IV) complexes induces the conformational change with the loss of α-helicity in the proteins. Docking studies indicate that mode of binding of oxovanadium(IV)-salen complexes with proteins is hydrophobic in nature.

Bioactivated protein-based porous microcarriers for tissue engineering applications

Lipoaspirate-derived extracellular matrix enrichment was able to provide the necessary cell adhesion receptors and biological factors for improving cell–material interactions of porous OVA microcarriers.

Combined effect of glycation and sodium carbonate-bicarbonate buffer concentration on IgG binding, IgE binding and conformation of ovalbumin

BACKGROUND

Ovalbumin (OVA) is a major allergen in hen egg. During thermal processing, reducing sugars contained in the hen egg white might easily undergo glycation with OVA, but few studies have been conducted on its corresponding immunoreactivity changes. The aim of the present study was to assess changes of the antigenicity, potential allergenicity and conformation of OVA after glycation in a wet-thermal processing system under different concentrations of sodium carbonate-bicarbonate buffer.

RESULTS

IgE binding of the glycated OVA was increased after glycation, and the higher the sodium carbonate-bicarbonate buffer concentration, the higher the IgE binding capacity. The increase in IgE binding of OVA corresponded well with the disruption of the disulfide bond, which exposed the epitopes initially buried. Antigenicity of the glycated OVA was increased, and the amount of the increase varied among samples treated under different buffer concentrations.

CONCLUSION

Glycation increased the allergenic potential for OVA, with the amount of increase varying with different sodium carbonate-bicarbonate buffer concentrations.