Studies on the specificity of the binding site of Vicia graminea anti-N lectin

Detection of Lectin Protein Allergen of Kidney Beans (Phaseolus vulgaris L.) and Desensitization Food Processing Technology

With the increase of food allergy events related to not properly cooked kidney beans (Phaseolus vulgaris L.), more and more researchers are paying attention to the sensitization potential of lectin, one of the major storage and defensive proteins with the specific carbohydrate-binding activity. The immunoglobulin E (IgE), non-IgE, and mixed allergic reactions induced by the lectins were inducted in the current paper, and the detection methods of kidney bean lectin, including the purification strategies, hemagglutination activity, specific polysaccharide or glycoprotein interactions, antibody combinations, mass spectrometry methods, and allergomics strategies, were summarized, while various food processing aspects, such as the physical thermal processing, physical non-thermal processing, chemical modifications, and biological treatments, were reviewed in the potential of sensitization reduction. It might be the first comprehensive review on lectin allergen detection from kidney bean and the desensitization strategy in food processing and will provide a basis for food safety control.

Identification of Glycoproteins Isolated from Extracellular Polymeric Substances of Full-Scale Anammox Granular Sludge

ANaerobic AMMonium OXidation (anammox) is an established process for efficient nitrogen removal from wastewater, relying on anammox bacteria to form stable biofilms or granules. To understand the formation, structure, and stability of anammox granules, it is important to determine the composition of the extracellular polymeric substances (EPS). The aim of this research was to elucidate the nature of the proteins, which are the major fraction of the EPS and were suspected to be glycosylated. EPS were extracted from full-scale anammox granular sludge, dominated by " Candidatus Brocadia", and subjected to denaturing polyacrylamide gel electrophoresis. By further analysis with mass spectrometry, a high abundant glycoprotein, carrying a heterogeneous O-glycan structure, was identified. The potential glycosylation sequence motif was identical to that proposed for the surface layer protein of " Candidatus Kuenenia stuttgartiensis". The heavily glycosylated protein forms a large fraction of the EPS and was also located by lectin staining. Therefore, we hypothesize an important role of glycoproteins in the structuring of anammox granules, comparable to the importance of glycans in the extracellular matrix of multicellular organisms. Furthermore, different glycoconjugates may have distinct roles in the matrix of granular sludge, which requires more in-depth characterization of different glycoconjugates in future EPS studies.

Analytical Application of Lectins

This review is devoted to the analytical application of carbohydrate-binding proteins called lectins. The nature of lectins and the regularities of their specificity with respect to simple sugars and complex carbohydrate-containing biomolecules are discussed. The main areas of the modern analytical application of lectins are described. Lectin-affinity chromatography, histo- and cytochemical approaches, lectin blotting, microarray, and biosensor technologies as well as microplate analysis are considered in detail. Data on the use of lectins for the detection of cells and microorganisms as well as the study of protein glycosylation are summarized. The large potential of lectins as components of analytical systems used for the identification of glycans and the characteristics of their structure are substantiated.

Plant as a plenteous reserve of lectin

Lectins are clusters of glycoproteins of nonimmune foundation that combine specifically and reversibly to carbohydrates, mainly the sugar moiety of glycoconjugates, resulting in cell agglutination and precipitation of glycoconjugates. They are universally distributed in nature, being established in plants, fungi, viruses, bacteria, crustacea, insects, and animals, but leguminacae plants are rich source of lectins. The present review reveals the structure, biological properties, and application of plant lectins.

Lectins as tools in glycoconjugate research

Lectins are ubiquitous proteins of nonimmune origin, present in plants, microorganisms, animals and humans which specifically bind defined monosugars or oligosaccharide structures. Great progress has been made in recent years in understanding crucial roles played by lectins in many biological processes. Elucidation of carbohydrate specificity of human and animal lectins is of great importance for better understanding of these processes. Long before the role of carbohydrate-protein interactions had been explored, many lectins, mostly of plant origin, were identified, characterized and applied as useful tools in studying glycoconjugates. This review focuses on the specificity-based lectin classification and the methods of measuring lectin-carbohydrate interactions, which are used for determination of lectin specificity or for identification and characterization of glycoconjugates with lectins of known specificity. The most frequently used quantitative methods are shortly reviewed and the methods elaborated and used in our laboratories, based on biotinylated lectins, are described. These include the microtiter plate enzyme-linked lectinosorbent assay, lectinoblotting and lectin-glycosphingolipid interaction on thin-layer plates. Some chemical modifications of lectin ligands on the microtiter plates and blots (desialylation, Smith degradation, beta-elimination), which extend the applicability of these methods, are also described.

Carbohydrate-dependent binding of the cell-free hemagglutinin of Vibrio cholerae to glycoprotein and glycolipid

The carbohydrate-binding specificity of the cell-free hemagglutinin (HA) of Vibrio cholerae (K.K. Banerjee, A.N. Ghose, K. Datta-Roy, S.C. Pal, and A.C. Ghose, Infect. Immun.58:3698-3705, 1990) was studied by using glycoconjugates with defined sugar sequences. The HA was not inhibited by simple sugars including glucobiose, galabiose, and their N-acetylated derivatives. The hemagglutination of rabbit erythrocytes by the HA was inhibited moderately by fetuin, calf thyroglobulin, and human alpha 1-acid glycoprotein, all of which contain multiple asparagine-linked complex-type oligosaccharide units alone or in combination with serine/threonine-linked oligosaccharide units. The inhibitory potencies of the glycoproteins increased approximately 10-fold following removal of the terminal sialic acid and were completely destroyed by exhausative proteolysis. The HA agglutinated phosphatidylcholine liposomes containing GM1-ganglioside or its asialo-derivative in the presence of Ca2+ ions. The association constants of the complexes of the HA with asialofetuin, asialothyroglobulin, GM1-ganglioside, and asialo-GM1-ganglioside were determined by an enzyme-linked immunosorbent assay-based assay and found to be 1.7 x 10(7) M-1, 1.5 x 10(7) M-1, 1.8 x 10(7) M-1, and 2.4 x 10(7) M-1, respectively. Studies using chemically modified glycoproteins and plant lectins with defined sugar specificity revealed that the HA recognized the terminal beta 1-galactosyl moiety of these glycoconjugates. There was no evidence for the presence of an extended carbohydrate-binding domain in the HA molecule or a preference of the HA for a complex, branched oligosaccharide structure. Similar to the mechanisms proposed for the binding of cholera toxin and Shiga toxin to glycolipids and neoglycoproteins, the strong interaction of V. cholerae cell-free HA with glycoconjugates appeared to be a consequence of multiple weak binding to terminal beta1-galactosyl moieties of the glycoproteins or glycolipids.

Immunochemical studies on the combining site of the A + N blood type specific Moluccella laevis lectin

The specificity of the anti A+N lectin of Moluccella laevis (MLL) was examined by hemagglutination experiments with enzyme-modified human erythrocytes and by inhibition of hemagglutination. In addition, binding to various glycoproteins and inhibition by different sugars and glycoproteins were examined by enzyme immunoassay with antibodies to the lectin. Treatment of AMM erythrocytes with proteolytic enzymes increased their agglutinability by MLL 4-16-fold; similar treatment of ONN cells decreased their agglutinability 8-16-fold. This is in line with the known location and enzyme sensitivity of A and N specificity determinants. Treatment of the erythrocytes with sialidase increased their agglutinability and abolished the distinction between N and M cells. Hapten inhibition of hemagglutination of AMM and ONN erythrocytes by the lectin, and its binding to glycoproteins measured by enzyme immunoassay, confirmed the high specificity of MLL for N-acetyl-D-galactosamine (200-500 times more than for D-galactose) and suggested the presence of hydrophobic interactions around HO-2 of the D-galactose unit. The methyl alpha-glycosides of D-galactose and of N-acetyl-D-galactosamine were better inhibitors than the corresponding beta-glycosides; this preference was abolished, and sometimes reversed, when the p-nitrophenyl glycosides of the same monosaccharides were tested, stressing again the importance of hydrophobic interactions in the binding of carbohydrates to MLL. The lectin reacted well with ONN substance and with glycophorin A of the N phenotype (GPAN), but did not react with OMM substance or GPAM. The strongest inhibitor was asialo ovine submaxillary mucin, which contains many unsubstituted alpha-D-GalpNAc-(1-->3)-Ser/Thr residues; calculated per N-acetyl-D-galactosamine residue, it was 1500 stronger than free N-acetyl-D-galactosamine. In accordance with this result, it was found that the lectin strongly agglutinates Tn cells. The specificity of MLL can, thus, be defined as anti-Tn, crossreactive with blood types A and N, and with sialosyl-Tn. The N-specificity can best be explained by assuming that GPAN contains a small number of unsubstituted or partially sialylated alpha-D-GalpNAc-(1-->3)-Ser/Thr residues, which are present in smaller proportions, if at all, in GPAM.

Specificity of Amaranthus leucocarpus lectin

We have demonstrated that Amaranthus leucocarpus lectin hemagglutinating activity was powerfully inhibited by the T-antigen, containing Gal(beta 1-3)GalNAc(alpha 1-3)Ser/Thr, and the Tn-antigen, which contains GalNAc(alpha 1-3)Ser/Thr. This suggests that the acetamido group at C-2 and the axial -OH at C-4 of the N-acetyl-D-galactopyranosylamine ring are important for lectin binding. The hemagglutination assays also established that desialylated and Pronase-treated human type O erythrocytes with an M phenotype were better recognized than erythrocytes from all other blood groups. The recognition was dependent on pH and ionic strength.

Isolation, by affinity chromatography and gel filtration in 8 M-urea, of an active subunit from the anti-(blood-group A+N)-specific lectin of Moluccella laevis

The lectin from Moluccella laevis seeds agglutinates specifically blood-type-A and -N erythrocytes, and both activities are inhibited by micromolar concentrations of N-acetyl-D-galactosamine. The lectin consists of three subunits: a 67 kDa heterodimer, made up of two S-S-linked polypeptides of 28 and 46 kDa, and two non-covalently linked moieties of 26 and 42 kDa, the latter migrating after reduction with an apparent molecular mass of 46 kDa. Here we demonstrate that affinity chromatography of a crude protein fraction from M. laevis seeds on immobilized D-galactose in the presence of 8 M-urea affords a fully active lectin practically devoid of the 42 kDa subunit. We also present data showing that the 26 kDa subunit is devoid of cysteine residues, that the 28 kDa subunit contains two cysteine residues engaged in S-S bonds with the 46 kDa subunit, and that the latter has, in addition, two intramolecular cystine residues. Gel filtration on Sephadex G-150 in 8 M-urea/0.2 M-D-galactose of the lectin, affinity-purified in the presence of urea, afforded a pure 26 kDa subunit which exhibited both anti-A and anti-N activity, as well as high specificity for N-acetyl-D-galactosamine. In addition to demonstrating that the lectin is unusually stable and retains its carbohydrate-binding activity in 8 M-urea, our findings also show that the activity for different blood groups resides in the same subunit.

Separation and biochemical characterization of blood group N antigen precursor glycoproteins with Thomsen-Friedenreich (T) activity, T-active glycoproteins and N antigen precursor glycoproteins from ascites of primary ovarian cancer patients

1. Three perchloric acid-soluble fractions from ascites of three primary ovarian cancer patients were subjected to Sephacryl S-300 gel filtration, respectively, and three Fr. 1 which were eluted in the vicinity of void volume as minor fractions, were then separated by a systematic affinity chromatography using Vicia unijuga lectin-Sepharose CL-4B column and Arachis hypogaea lectin-Sepharose CL-4B column into three glycoproteins, blood group N antigen precursor glycoprotein with Thomsen-Friedenreich (T) activity, T-active glycoprotein and N antigen precursor glycoprotein, respectively. 2. These nine glycoproteins separated in yields of 0.1-1.3 mg per 100 ml of ascites, were demonstrated to be mucin-type glycoproteins with Mw of 1,791,000-4,921,000 and contained 33.8-56.1% carbohydrates.

Purification and partial characterization of two lectins from the cactus Machaerocereus eruca

Two lectins (MEAI and MEAII) were isolated from the cactus Machaerocereus eruca by affinity chromatography on mucin-Sepharose and partially characterized with respect to their biochemical and carbohydrate binding properties. Both are oligomeric glycoproteins consisting of 35 kDa monomers. Amino acid analysis indicates that both lectins have similar composition with high amounts of glycine, glutamic acid and serine. MEAI and MEAII contain approximately 36 and 24% (w/w) of carbohydrates, respectively. They agglutinate erythrocytes from several animal species. Binding specificity was directed to galactose-containing oligosaccharides and glycopeptides. The M. eruca lectins are the first lectins to be isolated from a species belonging to the plant family of Cactaceae.

The Dantu erythrocyte phenotype of the NE variety. II. Serology, immunochemistry, genetics, and frequency

Red cells (RBC) possessing the low-frequency MNSs antigen Dantu from 36 Black individuals (21 propositi) were found to exhibit the NE variety of this phenotype, as judged from the electrophoretic glycophorin (GP) pattern, described in an accompanying article, and/or from the polybrene test which detects the decreased NeuAc level of these RBC. All known DantuNE RBC (53) exhibit the phenotype M+N+. This finding as well as family studies and immunochemical investigations demonstrate that the DantuNE allele encodes a blood group M-specific GP A. Thus, the strongly decreased GP A level of RBC from DantuNE heterozygotes represents the product of the Dantu allele and its normal counterpart. It is suggested that the formation of a complex with the anion channel protein (band 3) represents the prerequisite for optimum incorporation of GP A into normal RBC membranes. The hybrid GP in DantuNE RBC, produced in large quantity, might suppress the incorporation of GP A in a cis and trans manner via the formation of a complex with band 3. The hybrid GP in DantuNE RBC lacks U activity, but expresses N activity and a qualitatively altered s antigen, thus proving its GP B-GP A hybrid nature in conjunction with data described in the accompanying article. Screening of ficin-treated RBC with Vicia lectin revealed that the Dantu phenotype exhibits a frequency of about 0.005 in American Blacks and less than 0.001 in Germans.

A monoclonal anti-glycophorin A antibody recognizing the blood group M determinant: studies on the subspecificity

A mouse monoclonal antibody (425/2B, IgM) was obtained which shows specificity for blood group M determinant of glycophorin A. The antibody is pH-dependent. At pH 6-7 it reacted strongly with blood group M antigen, but also cross-reacted distinctly with N antigen. At pH 8.3 the antibody showed moderately decreased reactivity with M antigen, but no interaction with N antigen was detectable by hemagglutination, immunoblotting, or microplate ELISA. The direct binding studies and inhibition of 425/B antibody by untreated or modified blood group M and N glycoproteins or tryptic glycopeptides showed that the binding to the antigens was not affected by acetylation of their amino groups, or removal of amino-terminal amino acid residue. Desialylation of the antigens decreased their reactivity with the antibody and this effect was distinctly stronger at pH 7 than 8.3. The antibody reacted strongly at pH 7 and 8.3 with glycophorin B of Henshaw phenotype, whereas its reactivity with normal glycophorin B was weak or undetectable at these pH values, respectively. The results obtained indicated that anti-M specificity of 425/2B antibody is related to the 5th amino acid residue of glycophorin A (anti-Mgly specificity) and that pH shift from 7 to 8.3 changes the fine specificity of the antibody. At pH 8.3 the reactivity of the antibody is more dependent on glycine residue (higher anti-M specificity) and less dependent on sialic acid residues in the antigen.

A new agglutinin from the Tulipa gesneriana bulbs

Two agglutinins with different agglutinating activity exist in Tulipa gesneriana bulbs. One is the T. gesneriana lectin which agglutinates yeasts as reported previously [Oda, Y. and Minami, K. (1986) Eur. J. Biochem. 159, 239-245]. The other agglutinin is a new one which agglutinates animal erythrocytes and was purified from the tulip bulbs using affinity chromatography on thyroglobulin-Sepharose 4B. The agglutinin agglutinated mouse and rat erythrocytes at a minimum concentration of 2 micrograms/ml and 30 micrograms/ml respectively, but did not agglutinate erythrocytes from other animals and yeasts even at a concentration of 1000 micrograms/ml. The agglutinin appeared homogeneous by disc gel electrophoresis at pH 4.3 and gel filtration. Its relative molecular mass was determined by gel filtration to be approximately 40,000. It was suggested that the agglutinin was composed of two different subunits of 26 kDa and 14 kDa by sodium dodecyl sulfate/polyacrylamide gel electrophoresis analysis. Binding of radioiodinated agglutinin to mouse erythrocytes indicated that the presence of a high-affinity site with a dissociation constant of 2.00 X 10(-9) M. In inhibition experiments thyroglobulin glycopeptides were the most potent inhibitors; thyroglobulin was also a potent inhibitor. Orosomucoid and mucin showed weak inhibition. The other glycoproteins, glycopeptides and sugars examined showed no inhibition.

Evidence for the presence of an N-acetyllactosamine-type chain in epiglycanin

Mannose-labeled epiglycanin was prepared by incubation of TA3-Ha ascites cells with [2-3H]mannose, removal of the epiglycanin by incubation of viable cells with L-1-p-tosylamino-2-phenylethyl chloromethyl ketone-trypsin, and isolation of the large epiglycanin glycopeptides by gel filtration. Purification of epiglycanin glycopeptides was performed by wheat germ agglutinin affinity chromatography. Extensive incubation of epiglycanin with Pronase, followed by passage through a calibrated column of Bio-Gel P-4 (Column P-4), gave three fractions. The fraction of lowest apparent molecular weight, about 5000, upon incubation with a purified extract from F. meningosepticum containing an N-glycosyl hydrolase and an endo-N-acetyl-beta-D-glucosaminidase (T.H. Plummer et. al. (1984) J. Biol. Chem. 259, 10700-10704) and passage through Column P-4 gave a peak of radioactivity at apparent Mr 3000. Incubation of nonlabeled epiglycanin under similar conditions with the same enzyme preparation followed by passage through Column P-4, gave two peaks, based upon total mannose content. One of these, partially deglycosylated epiglycanin, was present in the void volume. Its composition indicated that approximately 80% of the mannose content of epiglycanin had been removed by the enzyme treatment, whereas no change was noted in the proportion of the other carbohydrate components. The effluent volume of the second peak coincided precisely with the peak obtained from the Pronase-cleaved fraction. Its composition and apparent Mr were consistent with those of an N-lactosamine-type chain with four antennae, Man3Gal4GlcNAc5NeuAc2-3.

Location of an epitopic site on epiglycanin by molecular immunoelectron microscopy

Antibodies of the IgM type present in rabbit anti-epiglycanin antiserum were purified by (NH4)2SO4 precipitation and by ion-exchange, affinity and gel-filtration chromatography. After papain treatment of this fraction, followed by gel filtration, the fraction with highest apparent Mr was incubated with epiglycanin, and the antigen-antibody complexes separated by gel filtration. These were examined by electron microscopy, using rotational shadow casting, and the photographs of the complexes were mapped for the locations of the antibody molecules on the extended epiglycanin molecules. Distribution of the frequency of attachment of immunoglobulin showed a strong tendency toward binding at one end of epiglycanin, suggesting the probable presence of only one epitope, probably a glycopeptide structure containing a beta-D-galactopyranosyl-(1----3)-2-acetamido-2-deoxy-D-galactose chain.

Effect of pH on the binding of Vicia graminea lectin to erythrocytes. Dependence on the chemical character of red-cell receptors

Binding of the radioactive Vicia graminea lectin to human blood-group M and N erythrocytes and to horse erythrocytes was studied at pH 6-10. Binding of the lectin to untreated human erythrocytes and to those treated with Vibrio cholerae neuraminidase increased severalfold from pH 6 to pH 8 and was maintained at the maximal level up to pH 9/9.5. On the other hand, interaction of V. graminea lectin with native or desialylated horse erythrocytes was not significantly affected by pH and small differences in the binding were opposite to those found with human erythrocytes: the binding decreased when pH increased from 6 to 9.5. Binding of the lectin to all erythrocytes tested at pH 10 was lowered to about 80% of the maximal values. The differences in pH dependence of V. graminea lectin binding to human and horse erythrocytes most probably resulted from the presence of amino groups in human red-cell receptors and their absence from receptors of horse erythrocytes. The earlier data on the enhancing effect of amino group modification on the interaction of human red-cell glycopeptides with V. graminea lectin support the conclusion that an increase in the lectin binding to human erythrocytes at pH 6-8 is confined to the decreased protonization of the receptor amino groups. V. graminea lectin was irreversibly inactivated at pH 3 and was inactivated by EDTA at pH 7.4 and reactivated by Ca2+ or Mn2+. This suggested that the lectin is a metaloprotein, requiring bivalent cations for the full binding activity. Some quantitative differences between the binding properties of V. graminea lectin, prepared from different batches of seeds, are reported.

Miltenberger Class I and II erythrocytes carry a variant of glycophorin A

The membranes from Miltenberger Class I (Mi I) and II (Mi II) erythrocytes, two rare variants at the blood group MNSs locus, exhibited an abnormal glycoprotein of 32 kDa apparent molecular mass sharply stained by the periodic acid/Schiff procedure and a decreased content of glycoprotein alpha (synonym glycophorin A, glycoprotein MN) as seen on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Purified 125I-labelled Vicia graminea lectin binds to the unusual 32 kDa glycoprotein separated from Mi I and Mi II erythrocyte membrane of blood group NN or MN, but no significant labelling of this band was observed with Mi samples typed MM. On the basis of such lectin-labelling experiments we have described two heterozygous MN, Mi I individuals that carry one copy of an M gene producing a normal alpha-glycoprotein with M-specificity and one copy of a MiI gene producing a 32 kDa glycoprotein with N-specificity. Further investigations have shown that the 32 kDa glycoprotein was immunoprecipitated by two mouse monoclonal antibodies (R18 and R10) reacting specifically with the external domain of glycoprotein alpha. These results demonstrate that Mi I and Mi II erythrocytes carry an unusual variant of glycoprotein alpha.