Purification and characterization of a lectin (plant hemagglutinin) with N blood group specificity from Vicia graminea seeds

Perineuronal net in the extrinsic innervation of the distal colon of mice and its remodeling in ulcerative colitis

The perineuronal net (PNN) is a well-described highly specialized extracellular matrix structure found in the central nervous system. Thus far, no reports of its presence or connection to pathological processes have been described in the peripheral nervous system. Our study demonstrates the presence of a PNN in the spinal afferent innervation of the distal colon of mice and characterizes structural and morphological alterations induced in an ulcerative colitis (UC) model. C57Bl/6 mice were given 3% dextran sulfate sodium (DSS) to induce acute or chronic UC. L6/S1 dorsal root ganglia (DRG) were collected. PNNs were labeled using fluorescein-conjugated Wisteria Floribunda (WFA) l lectin, and calcitonin gene-related peptide (CGRP) immunofluorescence was used to detect DRG neurons. Most DRG cell bodies and their extensions toward peripheral nerves were found surrounded by the PNN-like structure (WFA+), labeling neurons' cytoplasm and the pericellular surfaces. The amount of WFA+ neuronal cell bodies was increased in both acute and chronic UC, and the PNN-like structure around cell bodies was thicker in UC groups. In conclusion, a PNN-like structure around DRG neuronal cell bodies was described and found modulated by UC, as changes in quantity, morphology, and expression profile of the PNN were detected, suggesting a potential role in sensory neuron peripheral sensitization, possibly modulating the pain profile of ulcerative colitis.

A review of Vicieae lectins studies: End of the book or a story in the writing?

Vicieae tribe, Leguminosae family (Fabaceae), has been extensively studied. In particular, the study of lectins. The purification, physicochemical and structural characterizations of the various purified lectins and the analysis of their relevant biological activities are ongoing. In this review, several works already published about Vicieae lectins are addressed. Initially, we presented the purification protocols and the physicochemical aspects, such as specificity for carbohydrates, optimal activity in the face of variations in temperature and pH, as well metals-dependence. Following, structural characterization studies are highlighted and, finally, various biological activities already reported are summarized. Studies on lectins in almost all genera (Lathyrus, Lens, Pisum and Vicia) are considered, with the exception of Vavilovia which studies of lectins have not yet been reported. Like other leguminous lectins, Vicieae lectins present heterogeneous profiles of agglutination profiles for erythrocytes and other cells of the immune system, and glycoproteins. Most Vicieae lectins consist of two subunits, α and β, products of a single precursor protein derived from a single gene. The differences between the isoforms result from varying degrees of proteolytic processing. Along with the identification of these molecules and their characteristics, biological activities become very relevant and robust for both basic and applied research.

A lectin from the liverwort Marchantia polymorpha L

Bryophytes have been screened for lectins. From the liverwort Marchantia polymorpha (Marchiantiales) a lectin could be purified to homogeneity using a combination of ultrafiltration, size exclusion chromatography and ion exchange chromatography. SDS polyacrylamide gel electrophoresis, size exclusion chromatography and electrospray mass spectroscopy showed that the lectin is a monomeric protein with a M(r) of 16,134.64 +/- 2.93. Marchantia polymorpha lectin agglutinates erythrocytes of different mammalia and exhibits carbohydrate specificity against complex carbohydrate structures. This is the first report of a lectin isolated from liverworts.

Purification and characterization of anti-N lectin from Vicia unijuga leaves

1. An anti-N lectin was extracted from Vicia unijuga leaves with phosphate-buffered saline (PBS). Purification of the lectin was achieved, after pretreatment of the PBS extract by ammonium sulfate fractionation and absorption with human M erythrocytes, by using a combination of conventional chromatographic techniques with asialoglycophorin AN-Sepharose CL-4B affinity chromatography. Purification steps were followed by increase of specific activity. 2. Homogeneity of the purified lectin was demonstrated by HPLC and SDS-PAGE. The purified lectin was a glycoprotein with 11.4% carbohydrate and relatively high percentages of serine, threonine and aspartic acid residues and had a Mw of 120,000 Da. 3. This lectin agglutinated human N and MN erythrocytes, but did not agglutinate M erythrocytes. Hemagglutination of the lectin was inhibited by glycophorin AN and N-active sialoglycopeptide released from human N erythrocytes by treatment with Pronase or trypsin. However, it was not inhibited by any of mono- and di-saccharides, ABH-active glycoproteins, glycophorin AM and M-active sialoglycopeptide liberated from human M erythrocytes by treatment with Pronase or trypsin.

Number and distribution density of ABH and MN antigen sites on young and old human erythrocyte surfaces

There were no differences in the number of A and M antigen sites between young and old human erythrocyte surfaces. No essential differences in the number of A1, N and Vicia graminea N antigen sites could be observed between young and old erythrocytes. The number of B and H antigen sites on cell surface was significantly higher in young erythrocytes than in old ones. The distribution density of A and M antigen sites on young erythrocyte was remarkably higher than that on old ones. Compared with young erythrocytes, significant increases in the distribution density of A1, B, H, N and Vicia graminea N antigen sites were observed in aged erythrocytes. It is suggested from these and other observations that human erythrocyte aging is accompanied by elimination of a small amount of B and H antigens from cell membranes, while A, A1, M, N and Vicia graminea N antigens are not released from cell membranes during in vivo aging.

Preliminary investigation of the structure of the carbohydrate component of Vicia graminea lectin, a plant glycoprotein

Purified Vicia graminea lectin, isolated from seeds, was found to contain D-mannose, 2-acetamido-2-deoxy-D-glucose, L-fucose, D-galactose, and D-xylose in the molar ratios approximately 3.9:1.5:1.2:1.1:1.0. The oligosaccharides, obtained after hydrazinolysis of Vg-lectin, were N-reacetylated, reduced with sodium borohydride, and fractionated into two peaks. The first peak contained D-galactose, D-mannose, 2-acetamido-2-deoxy-D-glucose, and 2-acetamido-2-deoxy-D-glucitol in the molar ratios 6:3:2:0.7. After h.p.l.c. fractionation into five oligosaccharides, the second peak contained D-mannose, D-xylose, L-fucose, 2-acetamido-2-deoxy-D-glucose, and 2-acetamido-2-deoxy-D-glucitol. Methylation analysis suggested the following general structure for these oligosaccharides: (formula; see text).

The stimulation of human B and T lymphocytes by various lectins

The response of human peripheral blood lymphocytes to different lectins was tested in vitro by monitoring DNA synthesis, blast transformation, and mitotic activity. One group of lectins - RCA, VGA, HPA, PNA, and UEA - showed no stimulating effects at all. WGA and VVA induced DNA synthesis and blast transformation but failed in stimulating mitosis. The mitogens PHA, ConA, LCA, and PWM showed peaks of mitotic activity at 50-60 hours for PHA, 70 hours for ConA, 80 hours for LCA, and between days 4 and 5 for PWM. The stimulation of different subpopulations of lymphocytes was investigated by immunological methods for the detection of B- and T-cell-specific surface structures during the whole incubation period. PHA proved to be a predominantly T cell stimulating agent, whereas ConA seemed to activate a higher proportion of B cells than yet known. PWM and the so-called T cell mitogen LCA turned up to stimulate a large number of B cells, but lead also to a T cell activation. The analysis of SCE events in stimulation experiments with these two lectins showed the early proliferation of a cell population with low SCE frequencies and the late propagation of a cell population with higher SCE rates. It could be assumed that the first population is represented by B- and the second by T-cells.

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.

Isolation and characterization of a lectin from garden cress (Lepidium sativuum)

A lectin has been isolated from extracts of garden cress (Lepidium sativum) by affinity chromatography on human immunoglobulin-Sepharose. The lectin reacts with human erythrocytes without specificity for the A, B and 0 blood group. Erythrocytes of animal origin are also agglutinated by the lectin. The hemagglutinating activity is abolished by heating the lectin solution at 70 degrees C or by dialysis against strong acid buffers. The hemagglutination reaction is not inhibited by monosaccharides. Lectin-glycoprotein interactions are described and discussed.

Vicia graminea anti-N lectin: partial characterization of the purified lectin and its binding to erythrocytes

Vicia graminea lectin, purified by affinity chromatography, was homogeneous in sodium dodecylsulphate/polyacrylamide gel electrophoresis and migrated with a velocity corresponding to a molecular weight of 125 000. Heating of 0.1% sodium dodecylsulphate at 100 degrees C caused dissociation of the lectin into subunits with an apparent molecular weight of 31 000. The results of isoelectric focusing suggested non-identity of the lectin subunits and existence of several molecular forms of the lectin. The lectin was neither dissociated nor activated by succinylation, but was irreversibly inactivated by 8 M urea. The lectin was totally bound to concanavalin-A-Sepharose and could be eluted with alpha-D-mannopyranoside. Binding of the 125I-labeled Vicia graminea lectin to untreated and desialylated human erythrocytes of blood groups M and N, horse and bovine erythrocytes was characterized. The lectin was bound specifically to sites specific for blood group N on untreated human erythrocytes with an uniform affinity, and association constant Ka = 1.5 X 10(8) M-1. Desialylated human NN and MM erythrocytes bound more lectin, with a distinctly higher, but non-uniform affinity. Vicia graminea lectin bound weakly to horse erythrocytes, and the effect of their desialylation was similar to that obtained with human erythrocytes. The lectin was not bound either to untreated or to desialylated bovine erythrocytes. Binding of the labeled lectin to human NN erythrocytes was inhibited by desialylated glycoproteins of the M and N blood groups, by untreated N glycoprotein, and weakly by untreated M glycoprotein.

Isolation and properties of a lectin from the seeds of hairy vetch (Vicia villosa Roth)

The lectin of the seeds of hairy vetch (Vicia villosa Roth), which selectively binds murine cytotoxic T-lymphocytes, was purified by simple affinity-chromatographic procedures on two different N-acetyl-alpha-D-galactosaminyl-carriers. The lectin thus obtained is homogeneous on polyacrylamide-gel electrophoresis both in acid and alkaline media and has a mol. wt. of approx. 120000. The lectin molecule appears to comprise four subunits of equal electrophoretic mobility, contains 4.3% of covalently bound neutral sugar and 0.72 Mn and 0.94 Zn atoms respectively. The anti-(blood-group A1) specific erythroagglutinating activity of the lectin can be detected at a limit concentration of 15 microgram/ml and is inhibitable most effectively by N-acetyl-D-galactosamine.

Subunit structure of Vicia graminea anti-(blood-group N) lectin

The subunit of the Vicia graminea lectin with blood-group-N specificity was examined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and gel filtration in 6M-guanidinium chloride, and its molecular weights was found to be 25 000. The unique N-terminal sequence fof the first nine residues of the lectin confirmed that Vicia lectin consists of four identical chains non-covalently linked. Finally the microheterogeneity of the lectin shown by analytical isoelectric focusing is discussed.

Purification and partial characterization of a mitogenic lectin from Vicia sativa

From the seeds of Vicia sativa a lectin has been purified by affinity chromatography on Sephadex G-100, followed by specific elution with D-glucose. The lectin is a glycoprotein with a molecular weight of 70 000. The aminoacid composition and the total sugar content have been determined. This lectin agglutinates horse, rabbit and human erythrocytes, with no specificity for human blood groups, but does not agglutinate calf and sheep erythrocytes. The agglutinating activity is inhibited by mono-, di-, and trisaccharides with a pyranosyl residue whose free hydroxyl group in position 4 has the configuration of glucose, and by fructose. The lectin has mitogenic activity on human peripheral blood lymphocytes.