A major stress-inducible Mr-42000 wall glycoprotein of French bean (Phaseolus vulgaris L.)

A major wall protein of suspension-cultured cells of French bean has been isolated and characterised. It can be prepared from walls or the culture filtrate and in composition it is particularly rich in proline, valine and glutamic acid/glutamine and contains appreciable amounts of hydroxyproline. The N-terminus shows some glycosylation, while following chemical deglycosylation the first 38 residues were found to be identical to those of proline-rich proteins from soybean. However, the composition of the highly purified Mr-42000 bean protein differs considerably from the soybean proteins and must contain its own specific domains. An antibody was raised and used to demonstrate the inducibility of the Mr-42000 bean protein in response to elicitor action. The protein was found to be mainly localised in the intercellular spaces of the cortical cells of bean hypocotyls and at the wall-plasmalemma interface of xylem vessels, another potentially accessible compartment for pathogens. Following wounding, the protein was found to be generally distributed in the wall of epidermal and cortical cells of the hypocotyls. The Mr-42000 protein is cross reactive with antibodies raised to glycoproteins of the Rhizobium infection thread and the chitin-binding hydroxyproline-rich glycoprotein, potato lectin. These common epitopes together with the previously demonstrated chitin-binding properties of the bean protein indicate a role in host-microbial interactions. Furthermore, the Mr-42000 protein itself bound to the growing hyphal tips of the bean pathogen, Colletotrichum lindemuthianum.

Chitin-binding proteins in potato (Solanum tuberosum L.) tuber. Characterization, immunolocalization and effects of wounding

Tubers of potato (Solanum tuberosum L.) contain a number of chitin-binding proteins which have possible functions in defence against pathogens. A major protein of the tuber is the chitin-binding lectin which has been further characterized with respect to its antigenicity and N-terminal amino acid sequence. By using an antiserum monospecific for tuber lectin in unwounded potato the protein was found in the cytoplasm and vacuole, unusually for a hydroxyproline-rich glycoprotein, but consistent with its soluble nature in subcellular extracts. Little increased synthesis of the lectin precursor or the post-translationally modified form could be demonstrated in excised potato tuber discs. However, after wounding there is increased synthesis of another hydroxyproline-containing glycoprotein of Mr 57,000, which binds to chitin and shares common epitopes with the lectin. In comparison with the tuber lectin, this novel glycoprotein contains less hydroxyproline, but from its overall composition it is clearly not an underhydroxylated form of the tuber lectin. It differed in its N-terminal amino acid sequence and was much less glycosylated, although arabinose was still present. Synthesis of the Mr-57,000 polypeptide began after the initial burst of protein synthesis and increased, reaching a peak at 24 h after wounding. The protein was produced with its enzymes of post-translational modification, prolyl hydroxylase and arabinosyltransferase, concomitantly with the marker enzymes for wounding, phenylalanine ammonia-lyase and membrane-bound phenol oxidase and peroxidase.

The presence of glycoproteins in the cell membrane complex of a variety of keratin fibres

Cell membrane complex preparations have been extracted using formic acid from human hair and nail, and from the hair of sheep, alpaca, rabbit, rat, cat, and dog. On analysis they were found to have similar amino acid compositions and they all contained carbohydrate. The sugars were typical of those found in membrane glycoproteins and all preparations reacted with peroxidase-conjugated lectins.

Isolation and characterization of a seed lectin from elderberry (Sambucus nigra L.) and its relationship to the bark lectins

A third elderberry (Sambucus nigra L.) lectin (SNA-III) has been isolated from dry seeds by affinity chromatography on immobilized 2-acetamido-2-deoxy-D-galactose. This lectin is a blood-group, nonspecific glycoprotein containing 21% of carbohydrate, and is rich in asparagine (or aspartic acid), serine, glutamine (or glutamic acid), and glycine. Gel filtration on Superose 12 yielded a single symmetrical peak corresponding to mol. wt. 50,000, SDS-poly(acrylamide) gel (SDS-PAGE) electrophoresis showed a single polypeptide band of 33 kDa, indicating that the native protein is a dimer of identical subunits. Hapten-inhibition assays of the agglutination of red blood cells showed that 2-acetamido-2-deoxy-D-galactose is the best inhibitor, being twice as potent as D-galactose, melibiose, and 2-amino-2-deoxy-D-galactose. A comparison of SNA-III to the previously described elderberry-bark lectins, SNA-I and SNA-II, indicated that the seed lectin is well distinct from them.

Bleeding disorder (von Willebrand disease) in a quarter horse

Bleeding diathesis in a Quarter Horse filly was caused by von Willebrand disease. Hemorrhage occurred mainly from mucosal surfaces and after trauma. Quantitative and qualitative measurements of plasma von Willebrand factor (vWF) documented a specific deficiency of vWF high molecular weight multimers, and concurrently greater than expected deficiency of vWF activity relative to vWF concentration. These findings are characteristic of type-II von Willebrand disease in human beings. Application of vWF assays used in human and small animal medicine now permits evaluation of vWF and diagnosis of von Willebrand disease in horses with bleeding disorders.

A comparison of the lectin-binding properties of glycoconjugates from a range of Leishmania species

Constituent glycoconjugates of promastigotes of 14 different Leishmania strains from 6 different species were separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and subsequently stained with 14 125I-labelled lectins of different specificities. Autoradiography of the gels revealed lectin-specific glycoproteins and other glycoconjugates of known molecular weight. Similarities and differences in antigens and glycoproteins present in the strains are described. The possibility of identification or characterisation of Leishmania species from their electrophoretic behaviour and lectin-binding patterns is unlikely, but these results should be an aid to purification of glycoconjugates from particular strains by lectin-affinity chromatography.

Chemical composition and tissue distribution of the human CDw44 glycoprotein

The CDw44 glycoprotein was purified from 2.3 x 10(11) CD3+ CD4+ CD8- T-chronic lymphocytic leukaemia (CLL) cells using F10-44-2 monoclonal antibody affinity chromatography, DEAE-Sepharose anion-exchange chromatography, passage down carboxymethyl (CM)-Sepharose cation-exchange columns, wheat germ lectin affinity chromatography and gel-permeation chromatography. On elution in non-ionic detergents from the DEAE column, two distinct peaks of antigen activity were obtained. The CDw44 glycoprotein in each peak was a glycoprotein of 85,000 MW, but the amino acid composition of the peaks was noticeably different. Carbohydrate compositions showed that each peak contained approximately 30% (w/w) carbohydrate, the composition suggesting both O-linked and complex N-linked glycans. Modulation studies with the F10-44-2 antibody on normal peripheral blood mononuclear cells (PBMC) demonstrated that the CDw44 glycoprotein of T cells consisted of one fraction that was readily modulated, and the other which was resistant to modulation. Detailed tissue distribution studies for CDw44 were performed using the F10-44-2 antibody on frozen sections of human tissues. CDw44 has a restricted tissue distribution, but is found on many highly diverse cell types (e.g. T lymphocytes, smooth muscle cells, some secretory glands, skin epithelial cells).

Purification and characterization of an agglutinin from mucus of the snail Achatina fulica

The mucus of the snail Achatina fulica shows the presence of an agglutinin that nonspecifically agglutinates human erythrocytes. The agglutinin has been purified by affinity chromatography using Sepharose 4B-hog gastric mucin as the affinity matrix. Homogeneity was checked by polyacrylamide gel electrophoresis, immunodiffusion, immunoelectrophoresis, and gel filtration. The agglutinin is a glycoprotein of native molecular weight 70,000. The isoelectric point of the protein was found to be 8.0. The predominant amino acids are aspartic acid and glutamic acid (or amides) and serine, which account for 32% of the total amino acid residues. The agglutinin has 10% carbohydrate (wt/wt) and the most abundant sugar is N-acetylglucosamine. The cd spectra of the agglutinin show the presence of random coil conformation. The inhibition of hemagglutination data indicates that the agglutinin is specific for beta glycosides of D-Gal and D-GalNAc.

Trypanosoma cruzi: studies on the interactions of lectins with glycoconjugates of different zymodemes

Detergent extracts were made of eight strains of Trypanosoma cruzi which were representative of the principal zymodemes. The extracts were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the glycoproteins were reacted with 21 different 125I-labeled lectins and autoradiographed. The staining patterns with particular lectins varied considerably between strains. Concanavalin A stained up to 17 distinct bands in some strains. Other lectins such as peanut lectin only stained two bands in zymodeme 1 strains and none in the other zymodemes. The reaction of N-acetylgalactosamine-specific lectins with some bands indicated the presence of this sugar and this was confirmed by analysis of the extracts. The lectin staining patterns provided an insight into the glycoprotein composition of the bands and should indicate whether combinations of lectins can be used in affinity chromatography systems to purify the glycoproteins.

Chemical-modification studies of a unique sialic acid-binding lectin from the snail Achatina fulica. Involvement of tryptophan and histidine residues in biological activity

A unique sialic acid-binding lectin, achatininH (ATNH) was purified in single step from the haemolymph of the snail Achatina fulica by affinity chromatography on sheep submaxillary-gland mucin coupled to Sepharose 4B. The homogeneity was checked by alkaline gel electrophoresis, immunodiffusion and immunoelectrophoresis. Amino acid analysis showed that the lectin has a fairly high content of acidic amino acid residues (22% of the total). About 1.3% of the residues are half-cystine. The glycoprotein contains 21% carbohydrate. The unusually high content of xylose (6%) and fucose (2.7%) in this snail lectin is quite interesting. The protein was subjected to various chemical modifications in order to detect the amino acid residues and carbohydrate residues present in its binding sites. Modification of tyrosine and arginine residues did not affect the binding activity of ATNH; however, modification of tryptophan and histidine residues led to a complete loss of its biological activity. A marked decrease in the fluorescence emission was found as the tryptophan residues of ATNH were modified. The c.d. data showed the presence of an identical type of conformation in the native and modified agglutinin. The modification of lysine and carboxy residues partially diminished the biological activity. The activity was completely lost after a beta-elimination reaction, indicating that the sugars are O-glycosidically linked to the glycoprotein's protein moiety. This result confirms that the carbohydrate moiety also plays an important role in the agglutination property of this lectin.

Leaves of the Orchid Twayblade (Listera ovata) Contain a Mannose-Specific Lectin

A new lectin was isolated from leaves of the twayblade (Listera ovata). It is a dimeric protein built up of two subunits of M(r) 12,500. This lectin, which is the first to be isolated from a species of the family Orchidaceae, exhibits exclusive specificity towards mannose.

Further characterization of the cold agglutinin from the snail Achatina fulica

The cold agglutinin from the albumin gland of the snail Achatina fulica was purified to homogeneity by using sheep gastric mucin-Sepharose 4B as affinity column followed by gel filtration on Bio-Gel P-300. The homogeneity was checked by alkaline gel electrophoresis, immunodiffusion and immunoelectrophoresis. The purified cold agglutinin is a glycoprotein of native M2 220,000 consisting of three non-covalently bound subunits of Mr 84,000, 74,000 and 62,000 and having a pI value of 4.5. The predominant amino acids are aspartic acid and glutamic acid (or amides) and serine, which account for 39% of the residues. About 3% of the residues are half-cystine. The lectin is a glycoprotein with about 30.7% carbohydrate, the most abundant sugars being galactose, N-acetylgalactosamine and N-acetylglucosamine. Mannose, xylose and fucose are also present. The inhibition of agglutination of human umbilical-cord erythrocytes by the cold agglutinin is specific for methyl beta-D-galactoside and also for glycolipids present on cord erythrocytes. The c.d. data show only negative ellipticity values in the far-u.v. region for the protein at various concentrations and temperatures and also in the presence of the hapten lactose (at different concentrations), indicating the presence of a random-coil conformation in the agglutinin that varies according to temperature.

A New Lectin from Meadow Saffron (Colchicum automnale)

A lectin has been isolated from tubers of the meadow saffron (Colchicum autumnale). It is an octameric protein (M(r) 100,000) composed of 4A- and 4B-subunits of M(r) 15,000 and 10,000, respectively. It is a glycoprotein with 4.4% carbohydrate, the main sugars are (N-acetyl-) glucosamine, mannose, fucose, and xylose. Although the Colchicum autumnale agglutinin (CAA) agglutinates human red blood cells, it has a much higher activity with rabbit erythrocytes. With respect to its carbohydrate-binding specificity CAA behaves rather unusually as it is inhibited by lactose, galactose, N-acetylgalactosamine and related sugars when assayed with human red blood cells but not in assays with rabbit erythrocytes.

Prevalence of antibodies to 72-kilodalton glycoprotein (GP72) in patients with Chagas' disease and further evidence of zymodeme-associated expression of GP72 carbohydrate epitopes

Three competitive inhibition enzyme-linked immunosorbent assays were developed to examine the expression of the 72-kilodalton glycoprotein (GP72) and of a GP72 carbohydrate epitope in Trypanosoma cruzi strains and clones. A total of 148 strains and clones of known isozyme phenotype (principal zymodeme, Z) were tested. With monoclonal antibody 8G2B9 the enzyme-linked immunosorbent assay confirmed that the majority of Z1 strains and clones derived from them had undetectable levels of the carbohydrate epitope identified by antibody 8G2B9. This epitope was, however, readily detectable in all Z2, Z2(h), and Z3 strains and clones (P less than 0.001; 148 strains and clones tested). Zymodeme-associated differences in GP72 expression were not apparent from the enzyme-linked immunosorbent assay with monoclonal antibody WIC 226.4 (raised against periodate-treated GP72) or from that with rabbit anti-GP72 antiserum (84 or 119 strains and clones tested, respectively). Mice infected with culture-form metacyclic trypomastigotes of Z1, Z29, and Z3 or with blood-form trypomastigotes of Z1 and Z3 developed antibodies to affinity-purified GP72, showing that at least some GP72 epitopes are neither zymodeme specific nor stage specific. A total of 128 serum samples from patients with acute or clinically classified chronic Chagas' disease were assayed for immunoglobulin G (IgG) or IgM anti-GP72 antibodies. During the acute phase anti-GP72 IgM antibodies were elevated, whereas anti-GP72 IgG antibodies were low. There were no significant differences in anti-GP72 antibody levels among chronic-phase patient groups. Anti-GP72 antibodies were detected irrespective of the geographical origin of patients and irrespective of whether acute-phase blood parasitemias were due to Z1 (four patients) or Z2 (two patients).

Isolation and characterization of glycoprotein lectins from the bark of three species of elder, Sambucus ebulus, S. nigra and S. racemosa

Lectins have been isolated from the bark of three members of the family Caprifoliaceae, Sambucus nigra (elder), S. racemosa (red-berried elder) and S. ebulus (dwarf elder), by affinity chromatography on fetuin-agarose, ion-exchange and gel-filtration chromatography. They are all glycoproteins of M r 140 000 made up of at least four subunits. The lectin have similar but not identical amino-acid compositions and the carbohydrate content varies between 12% and 19% (w/w), the main sugars being (N-acetyl)glucosamine, mannose, fucose and xylose. Inhibition studies of hemagglutination with various mono- and oligosaccharides have shown that N-acetylgalactosamine and galactose together with galactose-containing oligosaccharides are the most effective inhibitors. There are some differences in specificity, in particular S. ebulus agglutinin is inhibited to the same degree by galactosamine, N-acetylgalactosamine and by galactose.

Trypanosoma brucei brucei variant surface glycoprotein contains non-N-acetylated glucosamine

The C-terminal amino acid of the variant surface glycoprotein of the parasitic protozoan Trypanosoma brucei brucei is glycosylated and the oligosaccharide has been shown to contain glucosamine. By acid hydrolysis, HNO2 deamination and 1H-n.m.r. studies we have demonstrated that the amino group of this glucosamine is not N-acetylated and is most probably unmodified.

Protein conformation of potato (Solanum tuberosum) lectin determined by circular dichroism

The structure of potato (Solanum tuberosum) lectin, which is a hydroxyproline-rich glycoprotein, has been investigated by circular dichroism. The spectra of the native lectin, and of the oxidized, reduced and carboxymethylated and deglycosylated derivatives were examined, as was a hydroxyproline-rich glycopeptide and its deglycosylated derivative. It is concluded that the lectin contains about 35% polyproline II conformation, 34% type II beta-turn and 31% irregular conformation. No indications were found for the presence of alpha-helix or beta-sheet conformations. The polyproline II conformation is heat-stable, but is markedly destabilized by deglycosylation. The type II beta-turn is destabilized by cleavage of disulphide bonds.

Comparative compositions of cell surface glycoconjugates isolated from Trypanosoma cruzi epimastigotes

Cell surface glycoconjugates of epimastigotes of Trypanosoma cruzi have been isolated and analyzed to give their amino acid and carbohydrate compositions. Those which have been investigated are a complex of three closely associated glycoproteins, GP24, GP31, GP37, and a lipopeptidophosphoglycan. The GP24-GP31-GP37 complex has an unusual amino acid composition with very low levels of hydrophobic amino acids, it contains 56% (w/w) carbohydrate, with mannose, galactose and glucosamine (presumably N-acetyl) being present in approximately equal quantities. The lipopeptidophosphoglycan also has low levels of hydrophobic amino acids and contains equal levels of mannose and galactose together with lesser amounts of (N-acetyl) glucosamine. The glycoconjugates are contrasted and compared with two other previously characterised cell surface glycoproteins (GP25 and GP72) from T. cruzi.

A comparison of tomato (Lycopersicon esculentum) lectin with its deglycosylated derivative

A deglycosylated derivative of tomato (Lycopersicon esculentum) lectin was prepared with the use of trifluoromethanesulphonic acid. Its properties were generally similar to those of the native lectin, but differences were evident in terms of relative agglutinating activity towards sheep, (untreated) human and trypsin-treated human erythrocytes. The two forms of tomato lectin were used in conjunction with a battery of specific antisera to investigate structural relatedness among solanaceous lectins. Immunological cross-reactivity between tomato, potato and Datura lectins depends on the integrity of the glycosylated region of those lectins; that between Datura lectin and other seed lectins, however, has a separate structural basis.