Effect of lectins from Diocleinae subtribe against oral Streptococci

Surface colonization is an essential step in biofilm development. The ability of oral pathogens to adhere to tooth surfaces is directly linked with the presence of specific molecules at the bacterial surface that can interact with enamel acquired pellicle ligands. In light of this, the aim of this study was to verify inhibitory and antibiofilm action of lectins from the Diocleinaesubtribe against Streptococcus mutans and Streptococcus oralis. The inhibitory action against planctonic cells was assessed using lectins from Canavaliaensi formis (ConA), Canavalia brasiliensis (ConBr), Canavalia maritima (ConM), Canavalia gladiata (CGL) and Canavalia boliviana (ConBol). ConBol, ConBr and ConM showed inhibitory activity on S. mutans growth. All lectins, except ConA, stimulated significantly the growth of S. oralis. To evaluate the effect on biofilm formation, clarified saliva was added to 96-well, flat-bottomed polystyrene plates, followed by the addition of solutions containing 100 or 200 μg/mL of the selected lectins. ConBol, ConM and ConA inhibited the S. mutans biofilms. No effects were found on S. oralis biofilms. Structure/function analysis were carried out using bioinformatics tools. The aperture and deepness of the CRD (Carbohydrate Recognition Domain) permit us to distinguish the two groups of Canavalia lectins in accordance to their actions against S. mutans and S. oralis. The results found provide a basis for encouraging the use of plant lectins as biotechnological tools in ecological control and prevention of caries disease.     

基于拟糖蛋白的电化学阻抗生物传感器用于糖与蛋白质相互作用的研究

以D-甘露糖和伴刀豆球蛋白(ConA)的相互作用为研究对象,利用美拉德反应将D-甘露糖共价结合到负载蛋白牛血清蛋白(BSA)的表面形成拟糖蛋白,然后将拟糖蛋白固定到玻碳电极表面,以拟糖蛋白表面的D-甘露糖为分子识别物质,构建了检测伴刀豆球蛋白(ConA)的电化学阻抗传感器。拟糖蛋白制备过程简单,D-甘露糖负载量大,在空间中提供多个结合位点,因此能与ConA形成多价复合物,提高了传感器的灵敏度。该传感器的响应值与ConA浓度的对数在5.0×10-11~5.0×10-9mol/L之间呈良好的线性关系,检出限为1.7×10-11mol/L,D-甘露糖和ConA之间的结合常数为2.6×106L/mol。该方法简单,可适用于不同糖和蛋白质相互作用的研究,为构建高灵敏度的电化学阻抗传感器提供了新思路。     

Lectins and/or xyloglucans/alginate layers as supports for immobilization of dengue virus particles

Formation of stable thin films of mixed xyloglucan (XG) and alginate (ALG) onto Si/SiO(2) wafers was achieved under pH 11.6, 50mM CaCl(2), and at 70 degrees C. XG-ALG films presented mean thickness of (16+/-2)nm and globules rich surface, as evidenced by means of ellipsometry and atomic force microscopy (AFM), respectively. The adsorption of two glucose/mannose-binding seed (Canavalia ensiformis and Dioclea altissima) lectins, coded here as ConA and DAlt, onto XG-ALG surfaces took place under pH 5. Under this condition both lectins present positive net charge. ConA and DAlt adsorbed irreversibly onto XG-ALG forming homogenous monolayers approximately (4+/-1)nm thick. Lectins adsorption was mainly driven by electrostatic interaction between lectins positively charged residues and carboxylated (negatively charged) ALG groups. Adhesion of four serotypes of dengue virus, DENV (1-4), particles to XG-ALG surfaces were observed by ellipsometry and AFM. The attachment of dengue particles onto XG-ALG films might be mediated by (i) H bonding between E protein (located at virus particle surface) polar residues and hydroxyl groups present on XG-ALG surfaces and (ii) electrostatic interaction between E protein positively charged residues and ALG carboxylic groups. DENV-4 serotype presented the weakest adsorption onto XG-ALG surfaces, indicating that E protein on DENV-4 surface presents net charge (amino acid sequence) different from E proteins of other serotypes. All four DENV particles serotypes adsorbed similarly onto lectin films adsorbed. Nevertheless, the addition of 0.005mol/L of mannose prevented dengue particles from adsorbing onto lectin films. XG-ALG and lectin layers serve as potential materials for the development of diagnostic methods for dengue.     

Rim-differentiation vs. mixture of constitutional isomers: A binding study between pillar[5]arene-based glycoclusters and lectins from pathogenic bacteria

Macrocycle-based glycoclusters, on account of their promising anti-adhesive properties against bacteria, are potential therapeutic alternatives to classic antibiotics through the much less explored anti-adhesive strategy. In this study, a series of constitutionally-pure pentavalent glycoclusters was prepared by conjugating assorted azido-carbohydrates onto a penta-propargyl rim-differentiated pillar[5]arene (RD-P[5]) scaffold through Cu(I)-catalyzed azide–alkyne cycloaddition “click” reactions. Their binding towards therapeutically relevant bacterial lectins, such as LecA and LecB from Pseudomonas aeruginosa and concanavalin A (ConA), were evaluated subsequently by isothermal titration calorimetric studies. Most of these isomer-free RD-P[5] pentavalent glycoclusters, except the fucosylated ones, display good affinities to lectins. Nonetheless, the dissociation constants observed are similar to those displayed by an analogous pentavalent glycocluster consisting of four P[5] constitutional isomers, in which the RD-P[5] component merely accounts for 7% in the mixture. Our results revealed that high constitutional purity is not essential for achieving effective multivalent interactions between P[5]-based glycoclusters and lectins, presumably as a result of the conformationally labile nature of the P[5] scaffold. This information provides valuable design principles for low-cost and facile syntheses of glycosylated P[5]s for biomedical applications.     

Dynamic light scattering as an efficient tool to study glyconanoparticle-lectin interactions

Glyconanomaterials, an emerging class of bio-functional nanomaterials, have shown promise in detecting, imaging and targeting proteins, bacteria, and cells. In this article, we report that dynamic light scattering (DLS) can be used as an efficient tool to study glyconanoparticle (GNP)--lectin interactions. Silica and Au nanoparticles (NPs) conjugated with D-mannose (Man) and D-galactose (Gal) were treated with the lectins Concanavalin A (Con A) and Ricinus communis agglutinin (RCA(120)), and the hydrodynamic volumes of the resulting aggregates were measured by DLS. The results showed that the particle size grew with increasing lectin concentration. The limit of detection (LOD) was determined to be 2.9 nM for Con A with Man-conjugated and 6.6 nM for RCA(120) with Gal-conjugated silica NPs (35 nm), respectively. The binding affinity was also determined by DLS and the results showed 3-4 orders of magnitude higher affinity of GNPs than the free ligands with lectins. The assay sensitivity and affinity were particle size dependent and decreased with increasing particle diameter. Because the method relies on the particle size growth, it is therefore general and can be applied to nanomaterials of different compositions.     

Interaction of lectins withYersinia pestis strains

The ability of lectins to interact with Yersinia pestis strains isolated from rodent fleas and human biological fluids, obtained from different geographic areas, was examined. Lectins of Canavalia ensiformis, Ulex europaeus, Phaseolus vulgaris, and Triticum vulgaris, as well as a new autochthonous lectin of Swartzia pickellii of undefined specificity, were used. Most of the Y. pestis strains did not agglutinate with U. europaeus or C. ensiformis lectin. However, P. vulgaris lectin agglutinated suspensions of all the bacillus strains used. Fifteen of the 19 strains tested positive for assays using S. pickellii lectin. It is believed this is the first report of Y. pestis strain agglutination by lectins. A similar agglutination pattern was obtained for lectins with specificity for oligosaccharides containing N-acetylglucosamine and S. pickellii lectin, which did bind to the affinity matrix chitin, a polysaccharide of N-acetylglucosamine. The use of bacterial strains and commercial lectins of defined specificity may be an approach to providing evidence about the lectin binding sites of undefined monosaccharide specificity.     

Electrochemically monitoring the binding of concanavalin A and ovalbumin

To evaluate protein-protein interactions, a new voltammetric method was developed using a protein labeled with an electroactive compound. Concanavalin A (ConA), which is a lectin, recognizes α-mannose residues. Because the ConA was to be bound to ovalbumin (OVA), which has a high-mannose sugar chain, ConA labeled with daunomycin was prepared as the probe to monitor the binding. The binding to OVA was caused by the label modification of the ConA. As a result, the electrode response of the labeled ConA decreased as the OVA concentration increased. The electrode response of the labeled ConA was linearly over the range of 1.5 × 10⁻¹⁰ and 1.5 × 10⁻⁹ M OVA. The relative standard deviation of 1.5 × 10⁻⁸ M labeled ConA and 1.5 × 10⁻¹⁰ M OVA was 6.9% (n = 5). The labeled ConA-OVA binding could then be conveniently monitored based on the change in response. In contrast, interactions between the labeled ConA and a protein with no specific sugar chain also were investigated. Incubation scarcely influenced the peak current of the labeled ConA. When several concentrations of OVA were added to a serum, good recovery determined it. Consequently, this method could be applied to the measurement of protein-protein interactions.     

Determination of the carbohydrate-binding site of Bauhinia purpurea lectin by affinity chromatography.

To determine the carbohydrate-binding site of Bauhinia purpurea lectin (BPA), a D-galactose- and lactose-binding lectin, a peptide which interacts with lactose was purified from endoproteinase Asp-N digests of BPA by chromatography on a lactose-Sepharose column. It consists of nine amino acids and its amino acid sequence is Asp-Thr-Trp-Pro-Asn-Thr-Glu-Trp-Ser. A tryptic fragment with the ability to interact with lactose was also purified and found to contain this sequence, consisting of nine amino acids. This nonapeptide was aligned in a part of the metal-binding region conserved in all legume lectins. The chemical synthesis of the nonapeptide was carried out by a solid-phase method and the synthetic peptide showed a lactose-specific binding activity in the presence of calcium. A chimeric lectin gene was constructed using a cDNA coding BPA in which the nonapeptide sequence was replaced by the corresponding region of the alpha-D-mannose binding Lens culinaris lectins. Although BPA is specific for beta-D-galactose, the chimeric lectin expressed in Escherichia coli was found to bind alpha-D-mannosyl-bovine serum albumin and this binding was inhibited by D-mannose.     

Electrochemical assay of concanavalin A-ovalbumin binding on magnetic beads

To monitor protein-glycoprotein interactions on magnetic beads, the present study developed an electrochemical assay of the binding between concanavalin A (ConA) and ovalbumin (OVA). The system was a powerful model that could be used to evaluate cell junctions. ConA with an electroactive daunomycin was immobilized on 6 different sizes of magnetic beads (diameter: 1.0-8.9 μm) through a cross-linking agent. Six sizes of OVA-beads (diameter: 1.0-8.9 μm) were also prepared using a similar method. The binding was evaluated using an oxidation peak of ConA with daunomycin because ConA recognized OVA with α-mannose residues. When binding took place on the beads' surface, the peak current was decreased due to the electroactive moieties being covered with OVA. When ConA/daunomycin-OVA binding was evaluated, the change of the peak current obtained by the beads (diameter: 8.9 μm) modified with ConA and daunomycin was the greatest in the presence of OVA-modified beads (diameter: 2.5 μm). In contrast, particle agglomeration was observed for the smallest beads (diameter: 1.0 μm) with ConA/daunomycin and OVA. The results suggested that ConA-OVA binding depended on the size of beads. Thus, this method could be applied to measure protein-glycoprotein interactions on the cell surface.     

Influence of the primary structure of enzymes on the formation of CaCO2 polymorphs: a comparison of plant (Canavalia ensiformis) and bacterial (Bacillus pasteurii) ureases

The influence of the primary structures of plant (Canavalia ensiformis) and bacterial (Bacillus pasteurii) ureases on the precipitation of calcium carbonate polymorphs in solutions of calcium salts and urea at room temperature was investigated. Despite a similar catalytic function in the decomposition of urea, these ureases exerted different influences on the crystal phase formation and on the development of unusual morphologies of calcium carbonate polymorphs. Spherical and uniform vaterite particles were precipitated rather than calcite in the presence of Bacillus urease, while the presence of Canavalia urease resulted in the precipitation of calcite only. Vaterite particles were shown to be built up of nanosized crystallites, proving the importance of nanoscale aggregation processes on the formation of colloidal carbonates. Reduction of the concentration of Bacillus urease in the reacting solution results in the formation of calcite crystals with a more complex surface morphology than the ones obtained by Canavalia urease. These differences may be explained by dissimilarities in the amino acid sequences of the two examined ureases and their different roles in nucleation and physicochemical interactions with the surface of the growing crystals, during the precipitation processes. This study exemplifies the diversity of proteins produced by different organisms for the same function, and the drastic effects of subtle differences in their primary structures on crystal phase formation and growth morphology of calcium carbonate precipitates, which occur as inorganic components in a large number of biogenic structures.     

Sequence‐Defined Introduction of Hydrophobic Motifs and Effects in Lectin Binding of Precision Glycomacromolecules

This study investigates the influence of an increasingly hydrophobic backbone of multivalent glycomimetics based on sequence‐defined oligo(amidoamines) on their resulting affinity toward bacterial lectins. Glycomacromolecules are obtained by stepwise assembly of tailor‐made building blocks on solid support, using both hydrophobic aliphatic and aromatic building blocks to enable a gradual change in hydrophobicity of the backbone. Their binding behavior toward model lectin Concanavalin A (ConA) is evaluated using isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) showing higher affinities for glycomacromolecules with higher content of hydrophobic and aromatic moieties in the backbone. Finally, glycomacromolecules are tested in a bacterial adhesion inhibition study against Escherichia coli where more hydrophobic backbones yield higher inhibitory potentials most likely due to additional secondary interactions with hydrophobic regions of the protein receptor as well as a change in conformation exposing carbohydrate ligands for increased binding. Overall, the results highlight the influence and thereby importance of the polymer backbone itself on the resulting properties of polymeric biomimetics.     

Differentiation of human serum samples by surface plasmon resonance monitoring of the integral glycoprotein interaction with a lectin panel

Bacterial infection and inflammation result in massive changes in serum glycoproteins. These changes were investigated by the interaction of the saccharide glycoprotein moiety with lectins. A panel of eight lectins (Canavalia ensiformis, Bandeiraea simplicifolia BS-I, Arachis hypogaea, Phytolacca americana, Phaseolus vulgaris, Artocarpus integrifolia, Triticum vulgaris and Pisum sativum) was used to differentiate human serum glycoproteins obtained from patients with various bacterial infections. Lectin functionalised sensing layers were created on gold-coated wafers and lectin-glycoprotein interactions were monitored by surface plasmon resonance. The interaction of the lectin panel with serum glycoproteins produces unique patterns. Principal component analysis (PCA) was used to analyse the patterns. The actual panel of eight lectins enabled discrimination between sera obtained from patients sick with bacterial infection and healthy patients. Extended lectin panels have the potential to distinguish between types of bacterial infection and identify specific disease state.     

Selectivity among two lectins: probing the effect of topology, multivalency and flexibility of "clicked" multivalent glycoclusters

The design of multivalent glycoconjugates has been developed over the past decades to obtain high-affinity ligands for lectin receptors. While multivalency frequently increases the affinity of a ligand for its lectin through the so-called "glycoside cluster effect", the binding profiles towards different lectins have been much less investigated. We have designed a series of multivalent galactosylated glycoconjugates and studied their binding properties towards two lectins, from plant and bacterial origins, to determine their potential selectivity. The synthesis was achieved through copper(I)-catalysed azide-alkyne cycloaddition (CuAAC) under microwave activation between propargylated multivalent scaffolds and an azido-functionalised carbohydrate derivative. The interactions of two galactose-binding lectins from Pseudomonas aeruginosa (PA-IL) and Erythrina cristagalli (ECA) with the synthesized glycoclusters were studied by hemagglutination inhibition assays (HIA), surface plasmon resonance (SPR) and isothermal titration microcalorimetry (ITC). The results obtained illustrate the influence of the scaffold's geometry on the affinity towards the lectin and also on the relative potency in comparison with a monovalent galactoside reference probe.     

A multiplexed bead assay for profiling glycosylation patterns on serum protein biomarkers of pancreatic cancer

A multiplexed bead-based immunoassay was developed to simultaneously profile glycosylation patterns of serum proteins to investigate their usefulness as biomarkers for pancreatic cancer. The multiplex assay utilized protein-specific capture antibodies chemically coupled individually to beads labeled with specific amounts of fluorescent dye. Captured proteins were detected based on the extent and specific type of glycosylation as determined by successive binding of fluorescent lectin probes. Advantages to this technique include the fact that antibodies coupled to the beads had minimal nonspecific binding to the lectins ConA/SNA, avoiding the step of chemically blocking the antibody glycans and the bead assays were performed in a 96-well filter plate enabling high-throughput screening applications with improved reproducibility. The assay was tested with ConA and SNA lectins to examine the glycosylation patterns of α-1-β glycoprotein (A1BG) and serum amyloid p (SAP) component for use as potential biomarkers for the detection of pancreatic cancer based on the results from prior biomarker studies. The results showed that the SNA response on the captured A1BG protein could distinguish chronic pancreatitis samples from pancreatic cancer with a p-value of 0.035 and for the SAP protein with SNA, a p-value of 0.026 was found between the signal of normal controls and the pancreatic cancer samples. For the ConA response, a decline in the signal for both proteins in the serum samples was found to distinguish pancreatic cancer from normal controls and renal cell carnoma samples (A1BG, p<0.05; and SAP, p<0.0001).     

Novel Approaches To Design Glycan-Based Antibacterial Inhibitors

The interactions between bacterial lectins and carbohydrates on the host cell surface can mediate bacterial adhesion, invasion, and immune evasion. Multivalency plays a key role in these binding events. However, additional molecular mechanisms greatly impact multivalent binding recognition. To develop specific and effective bacterial inhibitors, a deeper understanding of the complex underlying mechanisms of bacterial adhesion processes is necessary. By interfering with bacterial adhesion, synthetic multivalent glycoconjugates do not only have the potential to improve or replace antibiotic treatments, but also represent useful tools to study carbohydrate-pathogen interactions. In this review, we highlight a few recent advances in the synthesis and application of synthetic glycan-based scaffolds to uncover the nature of glycan-bacteria interactions and to design efficient bacterial inhibitors.     

Binding evaluation of isoform 1 fromCratylia mollis lectin to human mammary tissues

The phenomenon of altered carbohydrates in transformed cell surfaces has been studied through histochemical techniques using lectins. Specific binding patterns to normal and transformed mammary tissues were evaluated by Isoform 1 fromCratylia mollis lectin (Cra Iso 1). Protocols using a direct method, incubation of Cra Iso I conjugated to peroxidase (Cra Iso 1-Per) with mammary tissues, followed by diaminobenzidine and hydrogen peroxidase interaction, were performed. Neoplastic tissues, marked by Cra Iso 1, showed a higher intensity of staining than normal ones, in comparison withCanavalia ensiformis lectin, Concanavalin A (Con A), conjugated to peroxidase (Con A-Per). The assay with Cra Iso 1 also indicated a possible utilization of this lectin to characterize normal and transformed mammary cells.     

Purification,Partial Characterization,and CNBr-Sepharose Immobilization of a Vasorelaxant Glucose/Mannose Lectin from Canavalia virosa Seeds

A novel mannose/glucose-binding lectin from Canavalia virosa (designated as ConV) has been purified from seeds of C. virosa by affinity chromatography on a mannose-Sepharose 4B column. ConV strongly agglutinates rabbit erythrocytes and was inhibited by monosaccharides (D-mannose, D-glucose, and α-methyl-D-mannoside) and glycoproteins (ovalbumin and fetuin). SDS-PAGE revealed three bands corresponding to three subunits (α, β, and γ) confirmed by ESI mass spectrometry with exact mass of 25,480?±?2 Da, 12,864?±?1 Da, and 12,633?±?1 Da, respectively. The purified lectin was more stable in pH ranging from 7.0 to 9.0, supported up to 80?ºC without any loss in activity and unaffected by EDTA. ConV showed no toxicity against Artemia sp. nauplii and relaxed endothelized rat aorta, with the participation of the lectin domain. In our tests, the lectin immobilized on CNBr-Sepharose was capable of binding 0.8 mg of ovalbumin per chromatography, allowing the use of ConV as a tool for capture and purification of glycoproteins.     

Vesicle formed by amphiphilc cucurbit[6]uril: versatile, noncovalent modification of the vesicle surface, and multivalent binding of sugar-decorated vesicles to lectin

We report a novel vesicle formed by an amphiphilic CB[6] derivative, the surface of which can be easily modified via host-guest interactions by taking advantage of molecular cavities, readily accessible at the vesicle surface, and their strong affinity toward polyamines. Amphiphilic CB[6] derivative 1 synthesized by reaction between (allyloxy)12CB[6] and 2-[2-(2-methoxyethoxy)ethoxy]ethanethiol affords a vesicle that has been characterized by TEM, light scattering, and fluorescent dye entrapment experiments. Treatment of vesicle 1 with FITC (fluorescein isothiocyanate)-spermine conjugate ligand 2, in which spermine serves as a binding motif to CB[6] and FITC as a fluorescent tag, produced a surface-modified vesicle, which can be easily visualized by a confocal microscope. This result provides us with a new noncovalent, modular approach to the modification of vesicle surfaces. By treating the vesicle derived from the amphiphilic CB[6] with a tag-attached polyamine, we can easily decorate the surface of the vesicle with the tag. Sugar-decorated vesicles were prepared by this noncovalent method, and their interactions with concanavalin A (ConA) were studied. The binding constant of the vesicle decorated with mannose-spermidine conjugate 3 to ConA was measured to be approximately 3 x 104 M-1, which is almost 3 orders of magnitude higher than that of free ligand 3 to ConA (K = approximately 50 M-1). On the other hand, the binding constant of the vesicle coated with galactose-spermidine conjugate 4 to ConA was too small to be measured. These results illustrate the specific and multivalent interactions between the mannose-decorated vesicle and ConA. The ability for facile surface modification suggests many practical applications, including its use in targeted drug delivery and immunization.     

Detection of isoforms of recombinant human erythropoietin by various plant lectins after isoelectric focusing

A screening method to determine the binding behavior of lectins toward recombinant human erythropoietin (rHuEPO) was developed. Twenty-three different lectins were tested for this purpose. rHuEPO isoforms were separated by isoelectric focusing using the International Olympic Committee (IOC) and World Anti-Doping Agency (WADA) accredited method for the direct detection of the prohibited doping substance erythropoietin (EPO). For the visualization of the rHuEPO isoforms lectins were used instead of antibodies. Optimization of the screening protocol enabled the detection of a maximum number of rHuEPO isoforms. By means of this protocol information about the binding properties of a lectin toward each individual rHuEPO isoform was accessible. All evaluated lectins showed significant differences in their binding behavior. The most intense response was obtained with WGA, DSL, PHA-E, LEL, PSA, and LCA. While WGA, DSL, PHA-E, and LEL were able to bind all isoforms detected by the standard antibody, LCA and PSA demonstrated a clear preference for rHuEPO isoforms located in the more basic region of the electropherogram. Further lectins tested were ConA, succWGA, PHA-L, RCA, SNA, MAA, STL, ECL, GSL-II, SJA, SBA, UEA-I, Jacalin, PNA, DBA, GSL-I, and VVA. Compared to the lectins mentioned above, they showed reduced sensitivity. Endogenous and recombinant EPO only differ in the composition of their N- and O-glycan moieties. As lectins possess the unique ability to recognize subtle differences in glycan substructures, they represent an interesting approach for their structural characterization. Furthermore, they might be useful for affinity enrichment/purification of rHuEPO in doping control.     

Differential staining of western blots of avian egg white glycoproteins using diverse lectins

Avian egg white glycoproteins which differ in structure and carbohydrate composition, vary in their interactions with diverse lectins. Generally, wheat germ agglutinin (WGA) and concanavalin A (Con A) are used for the identification and separation of those of the chicken. In the present study, interactions of a battery of lectins, including: the above two, several galactophilic lectins (from Aplysia gonad (AGL), Erythrina corallodendron (ECorL), peanut (PNA) and Pseudomonas aeruginosa (PA-IL)), and fucose-binding lectins (from Ulex europaeus (UEA-I), Ulva lactuca (ULL) and P. aeruginosa (PA-IlL), which also binds mannose) with chicken, quail and pigeon egg white glycoproteins, were examined using both hemagglutination inhibition and Western blot analyses. The chicken egg white glycoproteins interacted most strongly with WGA, followed by Con A > AGL = PA-IlL. The quail glycoprotein order of affinities was: Con A > WGA = AGL = PA-IlL, while that of the pigeon was: AGL > PA-IL > WGA > Con A = PA-IlL. The blocking of the other lectins by the egg whites were insignificant. The results demonstrated the selectivity and efficiency of the five most reactive lectins for differential tagging of avian egg white glycoproteins and unveiled the profound heterogeneity of the latter, as well as the possible potential lectin usage for improving purification and quality control of the desired glycoproteins.