Purification and characterization of structural and functional properties of two lectins from a marine sponge Spheciospongia vesparia.

The purification, structural and functional characterization of two different lectins (named Svl-1 and Svl-2) has been reported from the marine sponge Spheciospongia vesparia. Purification procedure includes ammonium sulfate precipitation, combined with chromatography including Octyl-Sepharose-(NH4)SO4 hydrophobic column and DEAE-Toyopearl anion-exchange column using a high performance liquid chromatography. The similarities in function, specificity for saccharides, molecular weight, amino acid content and the N-terminal sequence of two lectins suggest that these proteins are isolectins. Amino acid composition and fluorescence analyses reveal that they contain an intrachain disulfide bridge, which might contribute to their high thermal stability. Furthermore, the purified lectins exhibit antibacterial activity against the gram-negative bacteria Pseudomonas aeruginosa and E. coli, indicating that they may be involved in a recognition strategy and may play a role in the defense response function of the sponge. This is the first report on the isolation of lectins from the S. vesparia. The purified lectins represent a potential possible candidate for future application in the recognition or treatment of cancer cells.

Antifungal activity of lectins against yeast of vaginal secretion

Lectins are carbohydrate-binding proteins of non-imune origin. This group of proteins is distributed widely in nature and they have been found in viruses, microorganisms, plants and animals. Lectins of plants have been isolated and characterized according to their chemical, physical-chemical, structural and biological properties. Among their biological activities, we can stress its fungicidal action. It has been previously described the effect of the lectins Dviol, DRL, ConBr and LSL obtained from the seeds of leguminous plants on the growth of yeasts isolated from vaginal secretions. In the present work the experiments were carried out in microtiter plates and the results interpreted by both methods: visual observations and a microplate reader at 530nm. The lectin concentrations varied from 0.5 to 256µg/mL, and the inoculum was established between 65-70% of trammitance. All yeast samples isolated from vaginal secretion were evaluated taxonomically, where were observed macroscopic and microscopic characteristics to each species. The LSL lectin did not demonstrate any antifungal activity to any isolate studied. The other lectins DRL, ConBr and DvioL, showed antifungal potential against yeast isolated from vaginal secretion. These findings offering offer a promising field of investigation to develop new therapeutic strategies against vaginal yeast infections, collaborating to improve women's health.

Effects of plant lectin from cobra lily, Arisaema curvatum Kunth on development of melon fruit fly, Bactrocera cucurbitae (Coq.).

The lectin from tubers of cobra lily, Arisaema curvatum Kunth was purified by affinity chromatography using asialofetuin-linked amino activated porous silica beads. The concentration dependent effect of lectin was studied on second instar larvae (64-72 hr) of Bactrocera cucurbitae (Coq.). The treatment not only resulted in a significant reduction in the percentage pupation and emergence of the adults from treated larvae but it also prolonged the remaining larval development period. A very low LC50 value, 39 mgl(-1) of lectin was obtained on the basis of adult emergence using probit analysis. The activity of three hydrolase enzymes (esterases, acid and alkaline phosphatases), one oxidoreductase (catalase) and one group transfer enzyme (GSTs: Glutathione S-transferases) was assayed in second instar larvae under the influence of the LC50 of lectin at increasing exposure intervals (0, 24, 48 and 72 hr). The Arisaema curvatum lectin significantly decreased the activity of all the enzymes except for esterases, where the activity increased as compared to control at all exposure intervals. The decrease in pupation and emergence as well as significant suppression in the activities of two hydrolases, one oxidoreductase and one GST enzyme in treated larvae of B. cucurbitae indicated that this lectin has anti-metabolic effect on the melon fruit fly larvae.

Lectin staining patterns in human gastric mucosae with and without exposure to Helicobacter pylori / Padrões de ligação de lectinas em mucosa gástrica humana com e sem exposição a Helicobacter pylori

The aim of the present study was to evaluate qualitative changes in the glycoconjugate expression in human gastric tissue of positive and negative patients for Helicobacter pylori, through lectins: Wheat Germ Agglutinin (WGA) and Concanavalin A (Con A). The lectins recognized differently the glycoconjugates in the superficial mucous layer at the gastric tissues. The results suggest a significant change in the carbohydrate moieties present on the surface of the gastric cells during infection.

O objetivo do presente estudo foi avaliar as mudanças qualitativas na expressão de glicoconjugados em tecidos gástrico humano de pacientes infectados ou não pelo Helicobacter pylori, através das lectinas: Wheat germ agglutinin (WGA) e Concanavalina A (Con A). As lectinas reconheceram diferentemente os glicoconjugados nas camadas mucosas superficiais do tecido gástrico. Os resultados sugerem mudanças significantes nas porções de carboidratos presentes nas células gástricas durante a infecção.

Differential activity of a lectin from Solieria filiformis against human pathogenic bacteria

A lectin isolated from the red alga Solieria filiformis was evaluated for its effect on the growth of 8 gram-negative and 3 gram-positive bacteria cultivated in liquid medium (three independent experiments/bacterium). The lectin (500 æg/mL) stimulated the growth of the gram-positive species Bacillus cereus and inhibited the growth of the gram-negative species Serratia marcescens, Salmonella typhi, Klebsiella pneumoniae, Enterobacter aerogenes, Proteus sp, and Pseudomonas aeruginosa at 1000 æg/mL but the lectin (10-1000 æg/mL) had no effect on the growth of the gram-positive bacteria Staphylococcus aureus and B. subtilis, or on the gram-negative bacteria Escherichia coli and Salmonella typhimurium. The purified lectin significantly reduced the cell density of gram-negative bacteria, although no changes in growth phases (log, exponential and of decline) were observed. It is possible that the interaction of S. filiformis lectin with the cell surface receptors of gram-negative bacteria promotes alterations in the flow of nutrients, which would explain the bacteriostatic effect. Growth stimulation of the gram-positive bacterium B. cereus was more marked in the presence of the lectin at a concentration of 1000 æg/mL. The stimulation of the growth of B. cereus was not observed when the lectin was previously incubated with mannan (125 æg/mL), its hapten. Thus, we suggest the involvement of the binding site of the lectin in this effect. The present study reports the first data on the inhibition and stimulation of pathogenic bacterial cells by marine alga lectins.

Hemagglutination pattern of galactose specific lectin from Pedilanthus tithymaloides in diabetes mellitus.

The usefulness of a galactose specific lectin from P. tithymaloides was examined to study the hemagglutination pattern in 193 patients with diabetes mellitus out of which 34 cases were of insulin dependent. A control of 72 normal subjects was also included. The hemagglutination titre against a partially purified lectin from P. tithymaloides of control group ranged from 9.1 to 170 units per mg protein with a mean value of 54 units per mg protein. Significantly low titre was observed in the cases with insulin dependent diabetes mellitus, while non-insulin dependent diabetes mellitus cases did not show any significant change. Further significant reduction in the titre in insulin dependent diabetes mellitus group was shown to occur along with the increased duration of the diabetic condition, reflecting measurable erythrocyte surface alterations.

Inhibition of bacterial respiration by a low-molecular weight lectin, scyllin, from Scylla serrata crab hemolymph.

Interaction of plant and/or invertebrate lectins with mammalian cells and different microorganisms is well known. In the present study, we have demonstrated that scyllin, a low molecular weight (MW 4000) lectin from the edible crab Scylla serrata hemolymph, purified by GalNAc-Sepharon affinity column followed by Mono-Q ion exchanger in FPLC exhibits antimicrobial activity against Bacillus cereus and Escherichia coli by inhibiting endogenous respiration as well as exogenous glucose oxidation. In both the cases oxygen consumption has been measured in an oxygraph. Scyllin has produced 50% inhibition of endogenous respiration at a concentration of 110 micrograms/ml and 125 micrograms/ml in B. cereus and E. coli respectively. It also reduced the exogenous glucose oxidation by 50% at a concentration of 12 micrograms/ml and 80 micrograms/ml respectively in B. cereus and E. coli. From the above study the mechanism of bacterial growth inhibitory property of scyllin is suggested though the other studies such as inhibition of nucleic acid biosynthesis, cell wall biosynthesis etc. to evaluate its total mode of inhibitory action are not yet obtained.

Further studies on vertebrate S-type lectins: cross-reactivity between toad and human lectins

Galectins (S-type or S-Lac lectins) are a well-defined family of beta-galactoside animal lectins characterized by a high sequence homology in the carbohydrate-binding domain. We have previously purified and characterized the S-type lectin from the ovary of the toad Bufo arenarum. In this study, we purified the S-type lectins from Bufo arenarum ovary and human spleen by an improved method which included ion exchange and affinity chromatography. Antibody cross-reactivities between both lectins and some other S-type lectins showed that they share epitopes. Glycosylation studies carried out with detection/differentiation kits suggested that both lectins are not glycosylated

Purification, physicochemical characterization and biological properties of a lectin from Erythrina velutina forma aurantiaca seeds

A lectin was purified from seeds of Erythrina velutina forma aurantiaca by affinity chromatography on cross-linked guargum. The lectin is a potent agglutinin for human (minimal concentration of protein able to cause visible agglutination of a 2 per cent erythrocyte suspension varying from 1 to 4 mug/ml), rabbit(4 mug/ml) and chicken erythrocytes (8 mug/ml) but presented low activity against cow (250 mug/ml) or sheep (333 mug/ml) blood cells. Hemagglutination of human O+ erythrocytes was inhibited by D-lactose (0.2 mM) > D-galactose(0.8 mM) > D-raffinose (2.1 mM). At pH 7.5, chromatography on a Superose 12 HR 10/30 column showed that the lectin was primarily a dimer (56.0 kDa) composed of two identical subunits (31.6 kDa each). A small amount of a tetrameric form was also apparently present. The lectin is a glycoprotein (7.3 per cent carbohydrate), has a pI of 4.5, contains high levels of acidic (Asp and Glu, 64.2 and 51.6 residues/mol, respectively) and hydroxy amino acids (Ser and Thr, 42.9 and 38.5 residues/mol, respectively) but relatively low amounts of sulfur amino acids (Cys and Met, 1.0 and 5.0 residues/mol, respectively) and has an N-terminal sequence of Val-Glu-Thr-Ile/Leu-Pro-Phe-Ser. Its hemagglutinating activity was abolished by heating at 70 degrees Celsius for 10 min. The activation energy (delta G') required for denaturation measured by loss of hemagglutination activity was 24.87 kcal/mol. In rats, the purified lectin (100 mug) induced neutrophil migration into the peritoneal cavity (3.7 ñ 0.6 x 10(6) neutrophils/ml) or into the air pouch (2.75 ñ 0.25 x 10(6) neutrophils/ml), 8 and 10 times greater than the negative control, respectively.

Isolation of the lectin and an L4 isolectin from Phaseolus vulgaris by affinity chromatography on insoluble ovomucoid

Lectins from extracts of Phaseolus vulgaris seeds have potent cell-agglutinating and lymphocyte-stimulating activity. An affinity adsorbent for lectins with specificity for the oligosaccharide structure was prpared by transforming ovomucoid, an oligosaccharide-rich glycoprotein, into an insoluble and stable gel. The ovomucoid was made insoluble by boiling a 20 per cent solution (200 mg/ml) in 0.1 M Tris-HCl, pH 8.9, for 20 min. This insoluble gel was desialylated by treatment with 50 mN sulfuric acid for 1h at 90ºC and fixed with 1 per cent glutaraldehyde, pH 7,4, for 10 min. The Phaseólus lectin and the L4 isolectin could be isolated essentially in a single-step procedure, using different eluting conditions: 50 mM sodium formate buffer, pH 3,0, was used for PHA elutions; a different column was eluted with 15 mM sodium tetraborate, pH 8.0, for desorbed L4 isolectin. Polyacrylamide gel electrophoresis of the lectin showed five distinct bands, whereas the L4 isolectin only presented one band. From 250 mg of saturated column, 8.25 mg of PHA was isolated. This adsorbent could be used several times with little change in binding capacity or selectivity

Diagnostic parameters of vascular neoplasms by immunohistochemistry.

Immunohistochemical identification of Factor VIII-related antigen and Ulex Europaeus A-I lectin as endothelial markers were studied in a series of 103 cases, comprising of benign and malignant vascular tumours, and few undifferentiated sarcomas. The results are correlated with that of others in this area and emphasizes the utility of these markers in surgical pathological diagnosis, especially to confirm the difficult diagnosis of angiosarcoma from other poorly differentiated sarcomas.

Aislamiento, purificación y caracterización de una lectina de la semilla del poró, Erythrina costaricensis (Leguminosae) / Isolation, purification and characterization of a lectin from the seed of Erythrina costaricensis (Leguminosae)

La lectina de la semilla de E. costaricensis se purificó a partir del extracto crudo mediante filtración por Sephadex G-100 y cromatografía por DEAE-Sephadex A-50. La electroforesis en gel de acrilamida (PAGE) demostró la presencia de una única banda proteica. El isoelectroenfoque analítico demostró la presencia de cuatro isolectinas. La masa relativa obtenida por filtración en Sephadex fue de 58 KDa y por PAGE en condiciones reductoras de 29.5 KDa. La proteína es fundamentalmente un dímero no unido por enlaces disulfuro, con un contenido de 6.5% de azúcares neutros. Es estable hasta 70-C y en un àmbito de pH de 2 a 10. Aglutina indistintamente los eritrocitos humanos y diferencia entre eritrocitos de origen animal, aglutinando los de conejo y pollo y no los de caballo, cabra, carnero ni rata. La galactosa N-acetil-galactosamina, lactosa y el EDTA inhiben su acción aglutinante, los iones calcio y mangneso son activadores. No se encontró efecto vasopresor al inyectar la lectina itravenosamente en ratas

Studies on the effect of various parameters on crotalarin-fetuin interaction.

With a view to optimise the interaction of crotalarin, a blood group A-specific lectin from the seeds of Crotalaria striata with fetuin the effect of various parameters on the reaction has been studied turbidimetrically. The formation of crotalarin-fetuin complex was dependent on time, temperature, pH and the ionic strength of the medium. The maximum turbidity appeared in 30 min at 20 degrees C and the pH optimum was 3.5. The binding constant (Ka) for crotalarin-fetuin interaction was 5.58 x 10(4) M-1 (pH 3.5) at 20 degrees C. Among the different inorganic salts tested, the cations with increasing concentrations had pronounced effect on binding. KCNS and KI, however, were noninhibitory. The turbidity slightly increased in presence of different sodium salts, whereas periodate and urea reduced the interaction. The different alcohols had no remarkable effect on the above reaction.

Plant lectins, chemical and biological aspects

Lectins, carbohydrate-binding proteins of non-immune origin, that agglutinate cells or precipitate polysaccharides and glycoconjugates, are well distributed in nature, mainly in the Plant Kingdom. The great majority of the plante lectins are present in seed cotyledons where they are found in the cytoplasm or int he protein bodies, although they have also been found in roots, stems and leaves. Due to their peculiar properties, the lectins are used as a tool both for analytical and preparative purposes in biochemistry, cellular biology, immunology and related areas. In agriculture and medicine the use of lectins greatly improved in the last few years. The lextins, with few exceptions, are glycoproteins, need divalent cations to display full activity and are, in general, oligomers with variable molecular weight. Although the studies on lectins have completed a century, their role in nature is yet ynknown . Several hypotheses on their physiological functions have been suggested. Thus, lectins could play important roles in defense against pathogens, plant-microorganism symbiosis, cell organization, embryo morphogenesis, phagocytosis, cell wall elongation, pollen recognition and as reserve proteins. A brief review on the general properties and roles of the lectins is given.

Lectinas, agentes antihemostáticos y compuestos positivos al reactivo de Dragendorff en algas marinas de Venezuela y Túnez / Lectins, antihaemostatic agents and dragendorff positive compounds in marine algae from Venezuela and Tunibia

Las algas marinas recolectadas en Túnez y Venezuela han sido analizadas buscando la presencia de lectinas, agentes antihemostáticos y compuestos Dragendorff positivo. De 34 especies estudiadas, la actividad de las lectinas fue demostrada en los extractos de 14 de ellas. De éstas, las especies consideradas de más valor para estudios posteriores fueron Halimeda tuna, H.opuntia, Bryotamnion triquetum, B. seaforthii, Codium isthmocladum y Centroceras clavulatum. La actividad anticoagulante fue detectada en extractos de 26 de las especies analizadas. El extracto con más actividad de potencia inhibidora fue el de Centroceras clavulatum, pero el de Codium isthmocladum también se consideró interesante. Once especies fueron estudiadas por su contenido de compuestos Drangendorff positivo. Tanto las betainas como el compuesto de sulfonio terciario del tipo 3-dimetilsulfoniopropinato (DMSP) o una mezcla de DMSP y una betaina fueron aisladas y caracterizadas en todas las especies analizadas

Isolation of a lectin from the marine sponge Desmapsama anchorata by affinity chromatography on raffinose-sepharose 6B

A mitogenic lectin for human lymphocytes is present in the marine sponge Desmapsama anchorata. The protein hemagglutinates red blood cells irrespective of ABO group antigens. We now report the isolation of this lectin, by affinity chromatography on a column of raffinose conjugated to epoxy-activated Sepharose 6B, in 8.3% yield and with a purification index of 27 based on hemagglutinating activity. The isolated lectin is a glycoprotein with two subunits with molecular weights of about 18 and 36 kDa which display carbohydrate combining sites of similar specificities and can be associated in different forms

Alpha-galactoside-binding isolectins from wild jack fruit seed (Artocarpus hirsuta): purification and properties.

Five isolectins with marked specificity for alpha-linked galactose were purified from the wild jack (Artocarpus hirsuta) seeds by affinity chromatography on cross-linked guar gum. They were composed of a glycosylated subunit A (Mr = 16 kDa) and a nonglycosylated subunit B (Mr = 11 kDa) in noncovalent association. The isolectins which eluted as a single peak of Mr 45 kDa on gel filtration in Biogel P-100 and in a TSK G-3000 SW high pressure column, were resolved into five peaks on electrophoresis at pH 4.5. Sodium dodecyl sulphate polyacrylamide gel electrophoreogram of the major isolectin band suggested that the isolectins may be the five possible tetrameric combinations of A and B subunits. The combined isolectins bound only two molecules of 4-methyl umbelliferyl alpha-D-galactoside with a binding constant of 4.75 x 10(4) M-1. The pH optimum of sugar binding was 7.0. The isolectins specifically bound to human IgG and IgA but not to IgM.

Isolation and funectional characterization of a mitogenic lection from the marine sponge Cinachyrella alloclada

1. A D-galactose-specific lectin was isolated from crude extracts of the marine sponge Cinachyrella alloclada by affinity chromatography on sepharose 4B. 2. The lectin agglutinated human erythrocytes irrespective of ther ABO group antigens. 3. Hemagglutination inhibition tests indicated that the lectin binds D-galactose or carbohydrates having a terminal nonreducing D-galactosyl group. 4. C. alloclada lectin was mitogenic for human periheral blood lymphocytes when AB serum was omitted during the first 24 h of culture. 5 Human serum apparently contains substances which bind or inactivate this lectin