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.     

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.     

Purification and characterization of a lectin from rice bran

A rice bran lectin was purified to homogeneity by precipitation with ammonium sulfate and chromatography on ovomucoid-Sepharose and CM-cellulose. The molecular weight of the dimer lectin was estimated to be around 37,000 by ultracentrifugation studies. The sedimentation coefficient was 3.8S. On Sepharose 6B gel filtration in the presence of 6 M guanidine-HCl, the lectin showed a molecular weight of 19,000. On reduction and carboxymethylation, the lectin further dissociated into two nonidentical subunits, with molecular weights of about 11,000 and 8,000. These subunits did not show hemagglutinating activity. Equilibrium dialysis experiments using N-acetyl-[1-14C]glucosamine indicated that about 1.8 mol of the sugar was bound to 19,000 g of the lectin. The lectin was mitogenic against mouse splenic lymphocytes and human peripheral lymphocytes. The lectin enhanced the rate of glucose oxidation and inhibited epinephrine-stimulated lipolysis in mouse adipocytes. Some characteristics of the lectin are compared with those of wheat germ agglutinin.     

Purification and partial characterization of a mitogenic protein released from preadipocytes of massively obese subjects

A protein released into the culture medium by omental preadipocytes of massively obese persons, which stimulates the replication of rat perirenal preadipocytes, has been purified to a high degree. By gel filtration chromatography, the molecular mass of the mitogenic protein was approximately 66,000 daltons (Da), while on sodium dodecyl sulfate - polyacrylamide gel electrophoresis, two subunits were obtained, relative masses (Mr) of approximately 31,000 and approximately 35,000. The isoelectric point of the approximately 66,000 Da entity was 5.6 +/- 0.2. By specific radioreceptor assay, the purified protein was related to epidermal growth factor and transforming growth factor alpha. It was not related to insulin-like growth factors I and II by radioimmunoassay and radioreceptor assay. We propose that the approximately 66,000 Mr protein, and other mitogenic proteins released by preadipocytes from massively obese persons, act through paracrine-autocrine mechanisms and may play a role in the development of the hyperplasia of enlarged fat cells characteristic of massive corpulence.     

Purification and characterization of lectins from Vicia hirsuta

The presence of three lectins in the seeds of Vicia hirsuta (L.) S. F. Gray, a wild-growing vetch, was shown. The main lectin was purified to homogeneity by buffer extraction, ammonium sulfate precipitation, affinity chromatography on Sephadex G-100 and isoelectric focusing in granulated gel. By chromatofocusing instead of isoelectric focusing the yield was increased 5-fold. The lectin has a pi of 6.4. It is composed of large β-subunits (M_r 19.200) and small α-subunits (M_r 12.800) in a 1:1 ratio. The subunits can be separated on Sephadex G-75 when equilibrated with 6 M guanidine-HCl. The amino acid composition of the two different subunits has been determined. No sulfur-containing amino acids are present. The lectin resembles the lectins from legumes from the same cross-inoculation group, i.e. Lens culinaris, Lens esculenta, Pisum satiyum and several Vicia spp. by the same type of sugar specificity and amino acid composition.     

Purification and characterization of a lectin from Annona coriacea seeds

A novel lectin, denominated ACLEC, was isolated from Annona coriacea seeds, belonging to the Annonaceae family. The lectin presented one protein band in SDS-PAGE of 14 kDa. Of the sugars tested, Dglucose and D-mannose were the best inhibitors. A search sequence database showed that ACLEC had homology with other plant lectins, belonging to leguminous lectin family.     

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

A lectin with N blood group specificity was isolated from Vicia graminea seeds. This lectin was purified from a crude extract by precipitation with ammonium sulfate, DEAE-cellulose chromatography and Sephadex G-150 gel filtration. Purification steps were followed by increase of specific activity. Its homogeneity was demonstrated by polyacrylamide gel electrophoresis, immunoelectrophoresis, electrofocusing and ultracentrifugation. This lectin is an acid glycoprotein with 7.3% carbohydrate, a high percentage of serine and contains no sialic acid. The native lectin has a molecular weight about 100 000 and dissociates into four subunits of 25 000 as shown by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Preliminary hemagglutination inhibition has shown that the lectin was not inhibited by any of the monosaccharides contained in N blood group substances; however it was inhibited by the erythrocyte membrane major glycoprotein and the tryptic fragments obtained from erythrocytes.     

Purification and physicochemical characterization of a cotyledonary lectin from Luetzelburgia auriculata

A lectin was purified from the cotyledons of Luetzelburgia auriculata (Fr. All) Ducke by affinity chromatography on agarose-N-acetyl-D-galactosamine. The lectin is a potent agglutinin for rabbit erythrocytes, reacts with human red cells, but is inactive against cow, sheep, and goat erythrocytes. Hemagglutination of rabbit erythrocytes was inhibited by either 0.39 mM N-acetyl-neuraminic acid or N-acetyl-D-galactosamin, 12.5 mM D-lactose or D-melibiose, 50 mM D-galactose or raffinose. Its hemagglutinating activity was lost at 80 degrees C, 5 min, and the activation energy required for denaturation was 104.75 kJ mol(-1). Chromatography on Sephadex G-100, at pH 7.6, showed that at this hydrogenic ionic concentration the native lectin was a homotetramer (123.5 kDa). By denaturing SDS-PAGE, LAA seemed to be composed of a mixture of 29 and 15 kDa polypeptide subunits. At acidic and basic pHs it assumed different conformations, as demonstrated by exclusion chromatography on Superdex 200 HR 10/30. The N-terminal sequence of the 29 kDa band was SEVVSFSFTKFNPNQKDII and the 15 kDa band contained a mixture of SEVVSFSFTKFNPNQKDII and KFNQIVAVEEDTDXESQPQ sequences, indicating that these bands may represent full-length and its endogenous fragments, respectively. The lectin is a glycoprotein having 3.2% neutral carbohydrate, with a pI of 5.8, containing high levels of Asp+Asn and Glu+Gln and hydroxy amino acids, and low amount or absence of sulfur amino acids. Its absorption spectrum showed a maximum at 280 nm and a epsilon (1%) x (1cm) of 5.2. Its CD spectrum was characterized by minima near 228 nm, maxima near 196 nm and a negative to positive crossover at 210 nm. The secondary structure content was 6% alpha-helix, 8% parallel beta-sheet, 38% antiparallel beta-sheet, 17% beta-turn, 31% unordered and others contribution, and 1% RMS (root mean square). In the fluorescence spectroscopy, excitation of the lectin solution at 280 nm gave an emission spectrum in the 285-445 nm range. The wavelength maximum emission was in 334.5 nm, typical for tryptophan residues buried inside the protein.     

Preliminary characterization of the repeated DNA sequence from Vicia sativa

We have identified a family of interspersed repeated sequences present in about 40,000 copies in the genomes of Vicia sativa and its near relative Vicia faba. The element vif is at least 6 kb in length, and members of the repeat family display a degree of heterogeneity in restriction pattern. Homologous elements in V. faba are much more heterogeneous than their V. sativa counterparts; however, analysis of five different V. faba lines revealed substantially the same patterns, suggesting that this family was reamplified prior to the divergence of the lines studied.     

The chemical characterization of favin, a lectin isolated from Vicia faba.

We have determined the subunit structure of the glucose- and mannose-binding lectin favin, from Vicia faba. The molecule is composed of two nonidentical polypeptide chains held together by noncovalent interactions. We have determined the complete amino acid sequence of the smaller alpha chain (Mr = 5,571) and shown that it is homologous to the alpha chain of the lectins from lentil and pea and to residues 72 to 120 of concanavalin A (Con A). The larger beta chain (Mr = 20,000) contains carbohydrate and is homologous to the beta chain of lentil, pea, soybean, peanut, and red kidney bean lectins and is homologous to a portion of the Con A molecule beginning at residue 122. Favin also contains a minor component, beta' (Mr = 18,700), that closely resembles the beta chain but lacks carbohydrate and may, on the basis of apparent molecular weight, lack some part of the COOH-terminal region of the polypeptide chain. Although favin is similar to Con A, it, like the lentil and pea lectins, appears to lack residues corresponding to positions 1 to 71 of Con A. Because these residues contribute significantly to the carbohydrate binding site of Con A, the lack of this region in the otherwise homologous lectin favin suggests that the carbohydrate binding site of favin differs from that of Con A or that the region represented by residues 1 to 71 of Con A is located in a different portion (i.e. in the beta chain) of the favin molecule.     

Purification and characterization of N-acetyl-D-galactosamine-binding lectin from Falcata japonica

An N-acetyl-D-galactosamine-binding lectin from Falcata japonica seeds was purified by affinity column chromatography of N-acetyl-D-galactosamine coupled to epoxy-activated Sepharose 6B. A 1000-fold purification of lectin was obtained from the crude extracts. The purified lectin agglutinated blood group A red cells, but neither blood group B nor O red cells. Polyacrylamide gel electrophoresis of the lectin showed one diffuse band. Molecular weights of 125,000 and 117,000 were estimated by gel filtration and ultracentrifugal analysis, respectively. SDS-polyacrylamide gel electrophoresis of the lectin also showed a single band which has a molecular weight of 34,000. Therefore, the lectin molecule was estimated to be a tetramer composed of four identical non-covalently bound subunits. F. japonica lectin was a glycoprotein containing 5% total carbohydrate, and the amino acid composition was characterized by a high content of aspartic acid, serine and glycine, a low content of methionine and the absence of cysteine.     

棘托竹荪凝集素的纯化及其生化特性

棘托竹荪(Dictyophora echinovolvata Zang, Zheng et Hu)子实体经生理盐水抽提、硫酸铵沉淀、DEAE-Sepharose和Sephadex G-100柱层析纯化得到棘托竹荪凝集素(DEL).经PAGE显示单一条带,相对分子质量为38 000, 其亚基相对分子质量为18 900; 不含中性糖,IEF-PAGE测得其等电点为4.21.该凝集素对供试的4种血型人血和6种动物血的红细胞具有凝集作用,也能凝集小鼠淋巴细胞和小鼠S180肉瘤细胞,对兔红细胞的凝集作用可被乳糖和果糖所抑制.DEL含有15种氨基酸,其中天冬氨酸、谷氨酸、甘氨酸和缬氨酸含量较高; N-末端为丙氨酸.DEL对热不稳定,经50℃处理10 min,活性明显降低; 在pH 4.00～pH 10.14范围内较稳定; 其凝血活性依赖于Mn2 和Ca2 ,Mg2 和Zn2 则无影响.DEL对小鼠腹腔注射的半致死量为1 180 mg·kg-1.     

Purification and characterization of potato lectin

Potato lectin (Solanum tuberosum agglutinin, STA), purified by affinity chromatography on tri-N-acetylchitotriose-Sepharose 6B, has Mr approximately 100,000, as estimated by gel filtration on Sephadex G-150 and is an aggregating system with a monomer Mr = 54,000, as estimated by sedimentation equilibrium analysis. Equilibrium dialysis showed that STA (dimer) has two binding sites for a specific sugar per molecule. STA has a high content of sugar, most of which is L-arabinose, and is rich in Hyp and Cys. On interaction with specific sugars, STA induced a UV difference spectrum having positive peaks at 292 and 285 nm characteristic of tryptophyl residues. The association constants with chitin oligosaccharides, determined from the intensities of the difference spectra at various concentrations of sugars, increased with increasing chain length of the sugar. Association constants obtained by frontal affinity chromatography of chitin oligosaccharides with STA-Sepharose were in good agreement with those obtained by difference spectra, whereas the association constants obtained by frontal affinity chromatography of STA with di- and tri-N-acetylchitotriose-Sepharose were much higher, presumably owing to the effect of multivalency of ligands. The CD spectra of STA in the far UV region indicate the presence of 40% of beta- and 60% of unordered form, and no alpha-helix conformation, which supports the structure suggested by the amino acid composition and the high content of sugar.     

Purification and characterization of a lectin from the mushroom, Flammulina veltipes

A lectin was purified to homogeneity from the mushroom, Flammulina veltipes, by zinc acetate treatment and CM-cellulose column chromatography. Its molecular weight was estimated to be 20,000 by gel filtration and polyacrylamide gel electrophoresis. The lectin does not contain carbohydrate, half-cystine, methionine, or histidine. On gel filtration sith Sepharose 6B in the presence of 6M guanidine-HCl, the purified lectin dissociated into two nonidentical subunits, FVA-L (molecular weight, 12,000) and FVA-S (8,000). The hemagglutinating activity was retained only in the FVA-L subunit. The lectin is mitogenic with respect to mouse spleen lymphocytes.     

Purification and characterization of a lectin from Phaseolus acutifolius var. latifolius

The lectin from Phaseolus acutifolius var. latifolius has been purified to homogeneity by affinity chromatography using stroma-sephadex, gel filtration and electrofocusing. The purified lectin consists of four subunits of 21 Kd molecular mass each one with 7.4% w/w total carbohydrate. Red cells of human and animal species, are agglutinated but are not inhibited by a series of sugars. Mitogenicity and immunosuppressive activities were demonstrated. Agglutination requires magnesium and calcium ions.     

Purification and characterization of a thermostable mycelial lectin from basidiomycete Lentinus squarrosulus

Lectins are non-immune carbohydrate-binding proteins or glycoproteins with specific binding sites for certain glycoconjugates. Fungal lectins have been documented for their antitumour, antiproliferative, immunomodulatory, hypotensive and insecticidal effects. In the present study, a mycelial lectin having molecular mass 55 kDa has been purified and characterized from Lentinus squarrosulus. Biological action spectrum of the lectin revealed agglutination of all human blood types (A, B, O, AB), goat, sheep, rabbit and pig erythrocytes. Neuraminidase treatment of blood type O erythrocytes considerably augmented hemagglutination titre. Carbohydrate inhibition studies showed its high affinity to mucin and asialofetuin. Lectin was purified by a combination of ammonium sulphate precipitation, dialysis, ion exchange chromatography and gel filtration chromatography. Optimum pH for lectin activity was observed to be 6.5–8.0 and optimum temperature was 25–30°C. Lectin showed poor pH stability and was stable within pH 7.0–7.5. It was highly thermostable and could withstand temperature upto 70°C. Lectin activity was sensitive to ethylenediaminetetraacetic acid and denaturants.     

Purification and characterization of a new mannose-specific lectin from Sternbergia lutea bulbs

A new mannose-binding lectin was isolated from Sternbergia lutea bulbs by affinity chromatography on an α(1-2)mannobiose-Synsorb column and purified further by gel filtration. This lectin (S. lutea agglutinin; SLA) appeared homogeneous by native-gel electrophoresis at pH 4.3, gel filtration chromatography on a Sephadex G-75 column, and SDS-polyacrylamide gel electrophoresis, These data indicate that SLA is a dimeric protein (20 kDa) composed of two identical subunits of 10 kDa which are linked by non-covalent interactions. The carbohydrate binding specificity of the lectin was investigated by quantitative precipitation and hapten inhibition assays. It is an α-D-mannose-specific lectin that interacts to form precipitates with various α-mannans, galactomannan and asialo-thyroglobulin, but not with α-glucans and thyroglobulin. Of the monosaccharides tested only D-mannose was a hapten inhibitor of the SLA-asialothryroglobulin precipitation system, whereas D-glucose, D-galactose and L-arabinose were not. The lectin appears to be highly specific for terminal α(1-3)-mannooligosaccharides. The primary structure of SLA appears to be quite similar to that of the snow drop (Galanthus nivalis) bulb lectin which is a mannose-binding lectin from the same plant family Amaryllidaceae. The N-terminal 46 amino acid sequence SLA showed 7% homology with that of GNA. Abbreviations: AAA, Allium ascalonicum agglutinin (shallot lectin); ASA, Allium sativum agglutinin (garlic lectin); AUA, Allium ursinum agglutinin (ramsons lectin); DAP, 1,3-diaminopropane; GNA, Galanthus nivalis agglutinin (snowdrop lectin); HHA, Hippeastrum hybr. agglutinin (amaryllis lectin); LOA, Listera ovata agglutinin (orchid twayblade lectin); NPA, Narcissus pseudonarcissus agglutinin (daffodil lectin); PAGE, polyacrylamide gel electrophoresis; PBS, phosphate-buffered saline, SLA, Sternbergia lutea agglutinin; SDS, sodium dodecyl sulfate; Me, methyl; Bn, benzyl; PNP, p-nitrophenyl. This revised version was published online in August 2006 with corrections to the Cover Date.