Isolation and characterization of a mannose-binding lectin from leaves of the Chinese daffodil Narcissus tazetta.

A mannose-binding lectin was isolated from leaves of the Chinese daffodil Narcissus tazetta (family Amaryllidaceae) using a procedure that comprised extraction with aqueous buffer, ammonium sulfate precipitation, ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel Blue gel and mannose-agarose, and FPLC-gel filtration on Superose 12. The lectin was adsorbed on mannose-agarose and unadsorbed on DEAE-cellulose and Affi-gel Blue gel. It was an unglycosylated homodimer with a molecular mass of 26 kDa. Analysis of the N-terminal sequence of the N. tazetta lectin revealed considerable homology to lectins from the daffodil Narcissus pseudonarcissus, the snowdrop Galanthus nivalis (family Amaryllidaceae), the tulip Tulipa, and Kidachi aloe Aloe arborescens (family Liliaceae), and the orchid lectins (family Orchidaceae). The most striking likeness exists among the Amaryllidaceae lectins. The N. tazetta lectin exhibits hemagglutinating activity toward rabbit erythrocytes.     

Detection and characterization of a lectin from non-seed tissue ofPhaseolus vulgaris

The distribution of lectin in various tissues ofPhaseolus vulgaris L. (cv. red) has been investigated using a sensitive solid-phase enzyme immunoassay. Roots, leaves and stems from 3- to 4-week-old plants were screened for their lectin content; low levels could be detected in all organs, with a relative distribution of 37% in roots, 20% in leaves and 43% in stems. The lectin from stemsleaves and roots was then isolated from 5- to 6-week-old plants using extraction, salt fractionation and affinity chromatography on immobilized porcine thyroglobulin. A comparative study of the seed lectin and the lectin isolated from 5- to 6-week-old plants was made using hemagglutination, inhibition of hemagglutination, immunodiffusion, polyacrylamide and agarose electrophoresis. The results showed that lectin isolated from the different tissues was immunologically identical and exhibited the same subunit structure and similar isolectin composition as the seed lectin.Abbreviations EDTA ethylenediaminetetraacetic acid - PHA phytohemagglutinin - SDS sodium dodecyl sulfate     

Isolation and Partial Characterization of a Seed Lectin from Tepary Bean that Delays Bruchid Beetle Development

Four isolectin forms of a seed lectin from mature seed of tepary bean (Phaseolus acutifolius) were isolated using solubility fractionation, affinity chromatography, and high performance liquid chromatography. The subunits are polypeptides with an apparent molecular mass of 30,000 daltons. The 30 kilodalton subunits are produced starting approximately 13 days after flowering and subsequently comprise a major fraction of the proteins found in the mature seed. The amino terminus of each isolectin fraction was determined to be highly homologous with that of the subunits of common bean (Phaseolus vulgaris L.) phytohemagglutinin (PHA). The tepary isolectin cross-reacts with both erythroagglutinating and leucoagglutinating subunits of PHA antibodies, although differential cross-reactivity was noted. A seed protein fraction enriched in tepary bean lectin was found to be toxic to bean bruchid beetles (Acanthoscelides obtectus), when incorporated into their diets at incremental concentrations from (1-5% w/w) above that of PHA concentrations in mature seeds of the susceptible common bean variety “Red Kidney.”     

Distribution of Lectins in the Jumbo Virginia and Spanish Varieties of the Peanut, Arachis hypogaea L

Peanut lectin was purified from seed meal of the Spanish and Jumbo Virginia varieties of peanut (Arachis hypogaea L.) by affinity chromatography on lactose coupled to Sepharose 4B. Polyacrylamide gel isoelectric focusing resolved the lectin preparation from Jumbo Virginia seeds into seven isolectins (pI 5.7, 5.9, 6.0, 6.2, 6.3, 6.5, and 6.7). Seed meal from the Spanish variety contained six isolectins which were indistinguishable from the pI 5.7, 5.9, 6.2, 6.3, 6.5, and 6.7 isolectins from Jumbo Virginia. Quantitative, lactose-specific hemagglutination was used to examine the lectins in tissues of both peanut varieties. In young (3- to 9-day-old) seedlings of each variety, more than 90% of the total amount of lectins detected in the plants was in the cotyledons. Most of the remainder was in hypocotyls, stems, and leaves; young roots contained no more than 4 micrograms of lectin per plant. Lectins were present in all nonroot tissues of 21- to 30-day-old seedlings, except 27-day-old Spanish hypocotyls. As cotyledons of each variety senesced, several of the more basic isolectins decreased to undetectable levels, but the acidic isolectins remained until at least 15 days after planting. Some of the seed isolectins and several apparently new lactose-binding lectins were also identified in affinity-purified extracts of 5-day-old roots and hypocotyls. Rabbit antibodies raised against the Jumbo Virginia seed isolectin preparation reacted with seed, cotyledon, and hypocotyl lectin preparations from both varieties. Analysis of seed lectin preparations from seven varieties of A. hypogaea and of a related species (A. villosulicarpa) indicated that isolectin composition in Arachis may be a characteristic of both the species and the subspecies (botanical type) to which the variety belongs.     

Systematic comparison of oligosaccharide specificity of Ricinus communis agglutinin I and Erythrina lectins: a search by frontal affinity chromatography

Ricinus communis agglutinin I (RCA120) is considered a versatile tool for the detection of galactose-containing oligosaccharides. However, possible contamination by the highly toxic isolectin 'ricin' has become a critical issue for RCA120's continued use. From a practical viewpoint, it is necessary to find an effective substitute for RCA120. For this purpose, we examined by means of frontal affinity chromatography over 100 lectins which have similar sugar-binding specificities to that of RCA120. It was found that Erythrina cristagalli lectin (ECL) showed the closest similarity to RCA120. Both lectins prefer Gal beta1-4GlcNAc (type II) to Gal beta1-3GlcNAc (type I) structures, with increased affinity for highly branched N-acetyllactosamine-containing N-glycans. Their binding strength significantly decreased following modification of the 3-OH, 4-OH and 6-OH of the galactose moiety of the disaccharide, as well as the 3-OH of its N-acetylglucosamine residue. Several differences were also observed in the affinity of the two lectins for various other ligands, as well as effects of bisecting GlcNAc and terminal sialylation. Although six other Erythrina-derived lectins have been reported with different amino acid sequences, all showed quite similar profiles to that of ECL, and thus, to RCA120. Erythrina lectins can therefore serve as effective substitutes for RCA120, taking the above differences into consideration.     

A genetic basis for the origin of six different isolectins in hexaploid wheat

Wheat (Triticum aestivum) germ agglutinin represents a complex mixture of multiple isolectin forms. Upon ion exchange chromatography at pH 3.8, three isolectins can be separated, each of which is composed of two identical subunits. At pH 5.0, however, three additional isolectins can be distinguished, which are built up of two different subunits (heteromeric lectins). Evidence is presented that these heterodimers are normal constituents of the wheat embryo cells. Analyses of the isolectin patterns in extracts from Triticum monococcum, Triticum turgidum dicoccum and Triticum aestivum, provide evidence that each genome, either in simple or complex (polyploid) genomes, directs the synthesis of a single lectin subunit species. In addition, a comparison of the isolectin pattern in these wheat species of increasing ploidy level, made it possible to determine unequivocally the genome by which the individual lectin subunits in polyploid species are coded for. The possible use of lectins in studies on the origin of individual genoms in polyploid species is discussed.Abbreviations CL cereal lectin - PBS phosphate buffered saline - SP Sephadex sulfopropyl Sephadex - WGA wheat germ agglutinin     

Distribution of glucose/mannose-specific isolectins in pea (Pisum sativum L.) seedlings

We report on the distribution and initial characterization of glucose/mannose-specific isolectins of 4- and 7-d-old pea (Pisum sativum L.) seedlings grown with or without nitrate supply. Particular attention was payed to root lectin, which probably functions as a determinant of host-plant specificity during the infection of pea roots by Rhizobium leguminosarum bv. viciae. A pair of seedling cotyledons yielded 545±49 g of affinity-purified lectin, approx. 25% more lectin than did dry seeds. Shoots and roots of 4-d-old seedlings contained 100-fold less lectin than cotyledons, whereas only traces of lectin could be found in shoots and roots from 7-d-old seedlings. Polypeptides with a subunit structure similar to the precursor of the pea seed lectin could be demonstrated in cotyledons, shoots and roots. Chromatofocusing and isoelectric focusing showed that seed and non-seed isolectin differ in composition. An isolectin with an isoelectric point at pH 7.2 appeared to be a typical pea seed isolectin, whereas an isolectin focusing at pH 6.1 was the major non-seed lectin. The latter isolectin was also found in root cell-wall extracts, detached root hairs and root-surface washings. All non-seed isolectins were cross-reactive with rabbit antiserum raised against the seed isolectin with an isolectric point at pH 6.1. A protein similar to this acidic glucose/mannose-specific seed isolectin possibly represents the major lectin to be encountered by Rhizobium leguminosarum bv. viciae in the pea rhizosphere and at the root surface. Growth of pea seedlings in a nitrate-rich medium neither affected the distribution of isolectins nor their hemagglutination activity; however, the yield of affinity-purified root lectin was significantly reduced whereas shoot lectin yield slightly increased. Agglutination-inhibition tests demonstrated an overall similar sugar-binding specificity for pea seed and non-seed lectin. However root lectin from seedlings grown with or without nitrate supplement, and shoot lectin from nitrate-supplied seedlings showed a slightly different spectrum of sugar binding. The absorption spectra obtained by circular dichroism of seed and root lectin in the presence of a hapten also differed. These data indicate that nutritional conditions may affect the sugar-binding activity of non-seed isolectin, and that despite their similarities, seed and non-seed isolectins have different properties that may reflect tissue-specialization.Abbreviations IEF isoelectric focusing - MW molecular weight - pI isoelectric point - Psl1, Psl2 and Psl3 pea isolectins - SDSPAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis The authors wish to thank Professors L. Kanarek and M. van Poucke for helpful discussions.     

Isolectin composition of individual clones of Urtica dioica: Evidence for phenotypic differences

Analysis of the isolectin composition of 102 individual nettle ( Urtica dioica L.) clones by ion-exchange chromatography revealed the occurrence of at least 11 different isolectins, which all had the same molecular structure and exhibited identical carbohydrate-binding specificity and agglutination properties. All 11 isolectins, however, did not occur simultaneously; 34 combinations of either 1, 2, 3, 4 or 5 isolectins were found. Since the occurrence of multiple molecular forms of the nettle agglutinin cannot be explained by the (partial) autotetraploid character of stinging nettle it is postulated to rely on the expression of a family of closely related lectin genes.     

<Emphasis Type="Italic">Narcissus tazetta</Emphasis> lectin shows strong inhibitory effects against respiratory syncytial virus,influenza A (H1N1, H3N2, H5N1) and B viruses

A mannose-binding lectin (Narcissus tazetta lectin [NTL]) with potent antiviral activity was isolated and purified from the bulbs of the Chinese daffodil Narcissus tazetta var. chinensis, using ion exchange chromatography on diethylaminoethyl (DEAE)-cellulose, affinity chromatography on mannose-agarose and fast protein liquid chromatography (FPLC)-gel filtration on Superose 12. The purified lectin was shown to have an apparent molecular mass of 26 kDa by gel filtration and 13 kDa by SDS-PAGE, indicating that it is probably a dimer with two identical subunits. The cDNA-derived amino acid sequence of NTL as determined by molecular cloning also reveals that NTL protein contains a mature polypeptide consisting of 105 amino acids and a C-terminal peptide extension. Three-dimensional modelling study demonstrated that the NTL primary polypeptide contains three subdomains, each with a conserved mannose-binding site. It shows a high homology of about 60%–80% similarity with the existing monocot mannose-binding lectins. NTL could significantly inhibit plaque formation by the human respiratory syncytial virus (RSV) with an IC₅₀ of 2.30 μg/ml and exhibit strong antiviral properties against influenza A (H1N1, H3N2, H5N1) and influenza B viruses with IC₅₀ values ranging from 0.20 μg/ml to 1.33 μg/ml in a dose-dependent manner. It is worth noting that the modes of antiviral action of NTL against RSV and influenza A virus are significantly different. NTL is effective in the inhibition of RSV during the whole viral infection cycle, but the antiviral activity of NTL is mainly expressed at the early stage of the viral cycle of influenza A (H1N1) virus. NTL with a high selective index (SI=CC₅₀/IC₅₀≥141) resulting from its potent antiviral activity and low cytotoxicity demonstrates a potential for biotechnological development as an antiviral agent.     

Lectins from bulbs of the Chinese daffodil Narcissus tazetta (family Amaryllidaceae).

The isolation of three lectins with similar N-terminal amino acid sequences from the bulbs of the Chinese daffodil Narcissus tazetta was achieved. The isolation protocol involved ion exchange chromatography on DEAE-cellulose, affinity chromatography on mannose-agarose, and fast protein liquid chromatography-gel filtration on Superose 12. The lectins were all adsorbed on mannose-agarose and demonstrated a single band with a molecular weight of 13 kDa in SDS-polyacrylamide gel electrophoresis and a single 26 kDa peak in gel filtration, indicating that they were mannose-binding, dimeric proteins. The lectins differed in hemagglutinating activity, with the magnitude of the activity correlating with the ionic strength of the buffer required to elute the lectin from the DEAE-cellulose column. The bulb lectin did not exert potent cytotoxicity against cancer cell lines or fetal bovine lung cells but inhibited syncytium formation in, and reinstated viability of, fetal bovine lung cells infected with bovine immunodeficiency virus.     

Galactoside-binding serum lectin of Xenopus laevis. Estrogen-dependent hepatocyte synthesis and relationship to oocyte lectin

Xenopus laevis serum contains a lectin which binds alpha- and beta-galactosides. It was purified to homogeneity by affinity chromatography and consists of a single subunit with Mr approximately 69,000, associated in a multimer. The lectin is synthesized and secreted by hepatic parenchymal cells, and its synthesis is increased about 2-fold by estrogen treatment, both in vivo and in primary cell cultures. The serum lectin has the same carbohydrate binding properties as an oocyte lectin from X. laevis described previously, is immunologically cross-reactive, and shows similarities in its peptide map. However, marked differences in amino acid composition preclude the possibility that the serum lectin is a precursor of the oocyte lectin.     

Characterization of isolectins inTetracarpidium conophorum seeds (Nigerian walnut)

A lectin preparation obtained fromTetracarpidium conophorum (Nigerian walnut) by affinity chromatography of seed extracts on lactose-agarose has been shown to contain two components by gel filtration on Sephadex G150. The larger componentTetracarpidium conophorum agglutinin I (TCAI) is a disulphide-bonded 70 kDa homodimer whereas the second component TCAII is a 34 kDa monomeric protein. Amino terminal aminoacid sequencing shows identity in TCAI and TCAII for the first fifteen residues after which the sequences diverge. TheN-terminal sequences of TCAI and TCAII show identity with sequences in the B-chains of ricin andRicinus communis agglutinin I (RCAI) in eleven of the initial fifteen residues. Thereafter TCAI appears to be homologous to the ricin B chain whereas TCAII is more homologous with the B chain of RCAI. A limited screening of the carbohydrate-binding specificity of TCAII by affinity chromatography of defined oligosaccharides on TCAII Sepharose columns shows that the binding specificity reported earlier for affinity purifiedTetracarpidium conophorum isolectins (Sato S, Animashaun T, Hughes RC (1991)J Biol Chem 266:11485–94) reflects the binding properties of TCAII which is the major isolectin in unfractionated lectin preparations.     

Mannose-specific isolectins with different hemagglutinating potencies isolated from Chinese daffodil (Narcissus tazetta var. chinensis) leaves

Three mannose-specific lectins exhibiting considerable similarities in NH₂-terminal amino acid sequence were isolated from leaves of the Chinese daffodil Narcissus tazetta (Family Amaryllidaceae). The purification protocol involved extraction with an aqueous buffer, anion exchange chromatography on DEAE-cellulose using stepwise elution with increasing salt concentrations, affinity chromatography on mannose-agarose, and FPLC-gel filtration on Superose 12. From the peak unadsorbed on DEAE-cellulose, and two peaks adsorbed on the ion exchanger and eluted respectively with 0.2 M Tris-HCl buffer and 0.5 M NaCl, were prepared fractions which yielded isolectins 1, 2, and 3 after adsorption on mannose-agarose and FPLC-gel filtraton. All three isolectins were homodimers with a molecular weight of 26 kDa. The lectin unadsorbed on DEAE-cellulose had the lowest, while the most strongly adsorbed lectin had the highest hemagglutinating activity.     

Distribution of cell surface saccharides on pancreatic cells

We describe here a simple, general procedure for the purification of a variety of lectins, and for the preparation of lectin-ferritin conjugates of defined molar composition and binding properties to be used as probes for cell surface saccharides. The technique uses a “universal” affinity column for lectins and their conjugates, which consists of hog sulfated gastric mucin glycopeptides covalently coupled to agarose. The procedure involes: (a) purification of lectins by chromatography of aqueous extracts of seeds or other lectin-containing fluids over the affinity column, followed by desorption of the desired lectin with its hapten suge; (b) iodination of the lectin to serve as a marker during subsequent steps; (c) conjugation of lectin to ferritin with glutaraldehyde; (d) collection of active lectin-ferritin conjugates by affinity chromatography; and (e) separation of monomeric lectin-ferritin conjugates from larger aggregates and unconjugated lectin by gel chromatography. Based on radioactivity and absorbancy at 310 nm for lectin and ferritin, respectively, the conjugates consist of one to two molecules of lectin per ferrritin molecule. Binding studies of native lectins and their ferritin conjugates to dispersed pancreatic acinar cells showed that the conjugation procedure does not significantly alter either the affinity constant of the lectin for its receptor on the cell surface or the number of sites detected.     

Polymorphism and glycoprotein character of Ricinus communis lectins purified by affinity chromatography]

Two lectin fractions (S20W = 6,8 and 4,9 S) were purified from Ricinus communis seeds. The purification was carried out in four steps : ammonium sulfate fractionation, affinity chromatography on Sepharose 4 B, gel filtration on Sephadex G 150 and chromatography on CM celluloes. The purified lectins were glycoproteins whose chemical composition was determined. Amino terminal analysis of the two fractions revealed glycine and serine. Polyacrylamide gel electrophoresis of the higher molecular weight fraction allowed the separation of several components with different affinity for PAS staining.     

Processing, Targeting, and Antifungal Activity of Stinging Nettle Agglutinin in Transgenic Tobacco

The gene encoding the precursor to stinging nettle (Urtica dioica L. ) isolectin I was introduced into tobacco (Nicotiana tabacum). In transgenic plants this precursor was processed to mature-sized lectin. The mature isolectin is deposited intracellularly, most likely in the vacuoles. A gene construct lacking the C-terminal 25 amino acids was also introduced in tobacco to study the role of the C terminus in subcellular trafficking. In tobacco plants that expressed this construct, the mutant precursor was correctly processed and the mature isolectin was targeted to the intercellular space. These results indicate the presence of a C-terminal signal for intracellular retention of stinging nettle lectin and most likely for sorting of the lectin to the vacuoles. In addition, correct processing of this lectin did not depend on vacuolar deposition. Isolectin I purified from tobacco displayed identical biological activities as isolectin I isolated from stinging nettle. In vitro antifungal assays on germinated spores of the fungi Botrytis cinerea, Trichoderma viride, and Colletotrichum lindemuthianum revealed that growth inhibition by stinging nettle isolectin I occurs at a specific phase of fungal growth and is temporal, suggesting that the fungi had an adaptation mechanism.     

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.     

An anti-A1 lectin in the seeds of Amphicarpaea bracteata

An anti-A1 lectin has been isolated from the extract of Amphicarpaea bracteata seeds by affinity chromatography on Epoxy-activated Sepharose 6B coupled to N-acetyl-D-galactosamine. The yield of the purified lectin was 86 microgram/g of seeds. The purified lectin shows one main band on electrophoresis in sodium dodecyl sulfate-polyacrylamide. The amino acid and neutral sugar composition indicate that this lectin is an acidic glycoprotein with a neutral sugar content of approx. 2%. The composition of the lectin is different from that of the Dolichos biflorus lectin but the two lectins have some common characteristics. The most powerful inhibitors of the agglutination of A1 red blood cells by the A. bracteata lectin is N-acetyl-D-galactosamine. Much weaker inhibitors of the agglutination are alpha-lactose, D-fucose, and five other sugars.     

The seed lectins of black locust (robinia pseudoacacia) are encoded by two genes which differ from the bark lectin genes

Two lectins were isolated from Robinia pseudoacacia (black locust) seeds using affinity chromatography on fetuin-agarose, and ion exchange chromatography on a Neobar CS column. The first lectin, R. pseudoacacia seed agglutinin I, referred to as RPsAI, is a homotetramer of four 34 kDa subunits whereas the second lectin, referred to as RPsAII, is composed of four 29 kDa polypeptides. cDNA clones encoding the polypeptides of RPsAI and RPsAII were isolated and their sequences were determined. Both polypeptides are translated from mRNAs of ca. 1.2 kb encoding a precursor carrying a signal peptide. Alignment of the deduced amino acid sequences of the different clones indicates that the 34 and 29 kDa seed lectin polypeptides show 95% sequence identity. In spite of this striking homology, the 29 kDa polypeptide has only one putative glycosylation site whereas the 34 kDa subunit has four of these sites. Carbohydrate analysis revealed that the 34 kDa possesses three carbohydrate chains whereas the 29 kDa polypeptide is only partially glycosylated at one site. A comparison of the deduced amino acid sequences of the two seed and three bark lectin polypeptides demonstrated unambiguously that they are encoded by different genes. This implies that five different genes are involved in the control of the expression of the lectins in black locust.Abbreviations LECRPAs cDNA clone encoding Robinia pseudoacacia seed lectin - LoLI Lathyrus ochrus isolectin I - PsA Pisum sativum agglutinin - RPbAI Robinia pseudoacacia bark agglutinin I - RPbAII Robinia pseudoacacia bark agglutinin II - RPsAI Robinia pseudoacacia seed agglutinin I - RPsAII Robinia pseudoacacia seed agglutinin II     

Isolation and Partial Characterization of a New Lectin from Seeds of the Greater Celandine (Chelidonium majus)

Seeds of the greater celandine (Chelidonium majus L.) contain a lectin which could be isolated using a combination of affinity chromatography on chitin and ion exchange chromatography on sulphopropyl-Sephadex. The purified lectin was partially characterized with respect to its biochemical and physicochemical properties. It is a small dimeric protein composed of two different subunits of M_r 9,500 and 11,500, respectively. Its amino acid composition is typified by high contents of glycine and cysteine. No covalently bound carbohydrate could be detected. Hapten inhibition experiments indicated that the lectin exhibits specificity towards oligomers of N-acetylglucosamine, the potency of inhibition increasing with chain length up to four residues. The greater celandine lectin is the first lectin to be isolated from a species belonging to the plant family Papaveraceae (poppy family). Although it represents a new type of plant lectin, resemblances to phytohemaglutinins from diverse taxonomic origin are obvious.