The bactericidal activity of lectins from nitrogen-fixing bacilli

Lectins I and II isolated from the nitrogen-fixing soil bacterium Paenibacillus polymyxa 1460 were found to be able to suppress the growth of Rhizobium leguminosarum 252 and Bacillus subtilis 36 at nearly all the concentrations tested (from 1 to 10 micrograms/ml). Lectin I was also inhibitory to Azospirillum brasilense 245 and Erwinia carotovora subsp. citrulis 603, while lectin II exerted bactericidal activity against Xanthomonas campestris B-610 and B-611 and A. brasilense 245. The bacillar lectins incubated with Rhizobium and Azospirillum cells caused leakage of low-molecular-weight substances from the cells, presumably resulting from impairment of the membrane barrier function. We believe that one of the possible mechanisms of the bacterial growth inhibition by lectins is mediated by the lectin-specific receptors occurring on the bacterial membrane, whose interaction with the lectin molecules induces conformational alterations in the membrane and concurrent malfunction of the metabolism of bacterial cells.     

The Role of Cell-Surface Lectins in the Aggregation of Azospirilla

The mutant strain Azospirillum brasilenseSp7.2.3 with impaired lectin activity exhibited poorer cell aggregation than its parent strain A. brasilenseSp7(S) both in the exponential and stationary growth phases. The pretreatment of bacterial cells with the specific haptens (L-fucose and D-galactose) of a lectin located at the cell surface of the mutant strain was found to inhibit the aggregation of azospirilla. The specific binding of the A. brasilenseSp7(S) lectin to the extracellular polysaccharide-containing complexes of this strain was revealed by dot immunoblotting on nitrocellulose membrane filters. The interaction of the lectins of A. brasilense75, A. brasilenseSp7, and A. lipoferum59b with the polysaccharide-containing complexes that were isolated from these strains was not specific. No interstrain cross-interaction between the exopolysaccharides and lectins of azospirilla was found. A coflocculation of A. brasilenseSp7 cells with Bacillus polymyxa1460 cells was shown. The involvement of autogenous lectins in the aggregation of bacterial cells is discussed.     

Protection of catheter surfaces from adhesion of Pseudomonas aeruginosa by a combination of silver ions and lectins

A catheter surface was modified by coating a cellulose acetate polymer. Adhesion of Pseudomonas aeruginosa ATCC 27853 to the surface was investigated by exposing bacterial cultures to three treatments: polymer impregnated with silver ions (Ag⁺), polymer surfaces coated with lectins and a combination of Ag⁺ and a lectin coating. The effective concentration of Ag⁺ providing protection against bacterial biofilm development was 100g/ml and higher. Lectins alone at 10% also showed inhibition of bacterial attachment. However, the best result was achieved against bacterial adhesion and growth on surfaces using a combination of 100 g Ag⁺/ml and a lectin coating as a surface treatment. This surface treatment was also effective against both fresh culture and a two-week-old culture containing P. aeruginosa producing exopolymers. Our results suggest that Ag⁺impregnation combined with a lectin coating warrants further investigation as a potential means of protecting catheters.     

Effect of Azospirillum Lectins on the Activities of Wheat-root Hydrolytic Enzymes

This work studied the effect of two cell-surface lectins isolated from the nitrogen-fixing soil bacterium Azospirillum brasilense Sp7 and from its mutant defective in hemagglutinating activity, A. brasilense Sp7.2.3, on the activities of α-glucosidase, β-glucosidase and β-galactosidase in the exocomponent, membrane and apoplast fractions of wheat-seedling roots. Lectin (40 μg mL⁻¹) incubation for 1 h of the plant fractions increased the enzymes’ activities; both wild-type and mutant lectins were most stimulatory to the activities of all the exocomponent-fraction enzymes studied and to the apoplast-fraction β-glucosidase. Pretreatment of the lectins with their carbohydrate hapten, L-fucose, lowered the effect. The observed differences in the lectins’ ability to influence enzyme catalytic activity are explained by change in the antigenic properties of the mutant lectin.     

Investigation of the Relationship between the Lectin Activity of Azospirilla and Their α-Glucosidase, β-Glucosidase,and β-Galactosidase

The activities of -glucosidase, -glucosidase, and -galactosidase were studied during the isolation and purification of lectins from Azospirillum brasilenseSp7 and Azospirillum lipoferum59b cells. These enzymatic activities were revealed in crude extracts of surface proteins, protein fraction precipitated with ammonium sulfate or ethanol–acetone mixture, and protein fraction obtained by gel filtration on Sephadex G-75. The distribution of the enzymes between different protein fractions varied for the azospirilla studied. The cofunction of the A. brasilenseSp7 lectin and -galactosidase on the cell surface is assumed. A strong interaction between the A. lipoferum59b lectin and glucosidases was revealed. The lectin from A. lipoferum59b may possess saccharolytic activity.     

Kinetic sedimentation of Rhizobium-aggregates produced by leguminous lectins

Lectins from Canavalia brasiliensis (CnBr), Cratylia floribunda (CFL), Vatairea macrocarpa (VML) and Phaseolus vulgaris (PHA) aggregate Rhizobiumbacteria. The relationship between specific sedimentation rate, (based on bacterial dry biomass) of bacterial aggregates and lectin concentrations was hyperbolic and showed bacterial surface affinity by lectins. R. tropici (Rt), R. leguminosarum bv. phaseoli (Rlp) and R. etli (Re) surfaces showed predominantly receptors of galactosidic nature. The Rt surfaces showed very high affinities (k _s = ±8.6 × 10^–8 ag lectin protein ml^–1) by Gal-specific lectins (PHA and VML), and very low affinities (k_s=± 4.9 × 10^–6) by Glc-specific lectins (CnBr and CFL). The Rlp surface had intermediate affinities by lectins. The Re surface showed high affinities by PHA (k_s= ±1.26 × 10^–8) and intermediate affinities by VML, CnBr and CFL. The relationship between sedimentation specific (based on lectin weight) and bacterial density was a sigmoid and showed lectin affinity by Rt surfaces. The bacterial sedimentation showed positive cooperative binding of lectins. The V_max induced by Glc-specific lectins was ±20 of that produced by Gal-specific lectins. The PHA affinity (k_s= 1.19 mg dry biomass ml^–1) was larger than VML (k_s = 1.23). The Glc-specific lectin affinities were smaller than those of Gal-specific. The apparent binding site number of lectins (n_app) was: 2.7-PHA; 2.2-VML; 3.2-CFL and 3.2-CnBr. The dissociation constant, k_s, of lectin-binding kinetics decreased with sugar-hapten treatment (10 M). The n_app decreased in PHA and CFL, increasing in VML + sugar-hapten treatment. This study showed that there is a difference in Rhizobium surfaces for lectin binding.     

Lectin binding sites on the surfaces of the pneumonocytes in human neonatal lung

Summary The surface coating of the pneumonocytes in human neonatal lung was studied by means of an electron microscope technique. Slices of aldehyde-fixed lung tissue were labelled with a horseradish peroxidase conjugate of one of the following lectins:Dolichos biflorus lectin,Triticum vulgaris lectin,Canavalia ensiformis lectin (concanavalin A),Limulus polyphemus lectin,Lotus tetragonolobus lectin andArachis hypogaea lectin. The tissue slices were then incubated in a diaminobenzidine—hydrogen peroxide medium and then postfixed in an osmium tetroxide solution. It was found that the type I and type II pneumonocytes were strongly labelled with the lectins ofTriticum vulgaris, Canavalia ensiformis, Limulus polyphemus andArachis hypogaea. The type I pneumonocytes were also strongly labelled withDolichos biflorus lectin but the staining of type II cells was relatively weak with this agent. Neither type of epithelial cell was labelled withLotus tetragonolobus lectin conjugate. These results suggest that the surface coating of the pneumonocytes in human neonatal lung contains the following carbohydrate groups:N-acetylgalactosamine,N-acetylglucosamine,-d-mannose,-d-galactose and sialic acid.     

Respiratory stimulus in Rhizobium sp. by legume lectins

High molecular weight lectins (> 100 kDa) from seeds of the legumes Canavalia brasiliensis (CnBr), Cratylia floribunda (CFL), Phaseolus vulgaris (PHA) and Vatairea macrocarpa (VML), temporarily stimulate the respiration of Rhizobium tropici-CIAT899 and R. etli-CFN42. These stimulants were significant (P < 0.05) in bacterial suspensions (> 2.85 mg dry biomass ml^–1), having at least 6200 molecules of lectins per bacteria. The VML (20 g ml^–1), induced specific O₂ demand of 2.3–2.5 M O₂ min^–1 mg dry biomass^–1, in CFN42 and CIAT899, respectively. However, CnBr, CFL and PHA induced smaller demands of O₂ (5×), in both strains. The order of affinities of the lectins was approximately VML > PHA > CFL > CnBr, with regard to respiratory stimuli in CIAT899 strain. The co-administration of 10 g VML ml^–1 and 9.8 M galactose, in CIAT899 suspensions, reduced the respiratory stimuli significantly in relation to the treatment with VML alone. These respiratory stimuli, induced by the lectins, increase the significance of the interaction lectin × Rhizobium in terms of bacterial physiology. Its understanding could be important in relation to bacterial symbiotic behaviour.     

Effect of lectins from <Emphasis Type="Italic">Azospirillum brasilense</Emphasis> to peroxidase and oxalate oxidase activity regulation in wheat roots

Lectins were extracted from the surface of nitrogen-fixing soil bacteria Azospirillum brasilense Sp7 and from its mutant A. brasilense Sp7.2.3 defective in lectin activity. The ability of lectins to stimulate the rapid formation of hydrogen peroxide related to increase of oxalate oxidase and peroxidase activity in the roots of wheat seedlings has been demonstrated. The most rapid induced pathway of hydrogen peroxide formation in the roots of wheat seedlings was the oxalic acid oxidation by oxalate oxidase which is the effect of lectin in under 10 min in a concentration of 10 μg/ml. The obtained results show that lectins from Azospirillum are capable of inducing the adaptation processes in the roots of wheat seedlings.     

Detection of lectins in nodulated peanut and soybean plants

The direct double-antibody enzymelinked immunosorbent assay system was used in the detection and measurement of seed lectins from peanut (Arachis hypogaea L.) and soybean (Glycine max L.) plants (PSL and SBL, respectively) that had been inoculated with their respective rhizobia. Concentrations of PSL dropped to undetectable levels in peanut roots at 9 d and stems and leaves at 27 d after planting; SBL could no longer be detected in soybean roots at 9 d and in stems and leaves at 12 d. A lectin antigenically similar to PSL was first detected in root nodules of peanuts at 21 d reaching a maximum of 8 g/g at 29 d then decreasing to 2.5 g/g at 60 d. There was no evidence of a corresponding lectin in soybean nodules.Sugar haemagglutination inhibition tests with neuraminidase-treated human blood cells established that PSL and the peanut nodule lectin were both galactose/lactose-specific. Further tests with rabbit blood cells demonstrated a second mannosespecific lectin in peanut nodule extracts that was not detected in root extracts of four-week-old inoculated plants or six-week-old uninoculated plants, although six-week-old root extracts from inoculated plants showed weak lectin activity. The root extracts from both nodulated and uninoculated plants contained another peanut lectin that agglutinated rabbit but not human blood cells. Haemagglutination by this lectin was, however, not inhibited by simple sugars but a glycoprotein, asialothyroglobulin, was effective in this respect.Abbreviations DAS double antibody sandwich - ELISA enzyme-linked immunosorbent assay - PBS phosphate-buffered saline - PSL peanut seed lectin - SBL soybean lectin     

Stabilizing effect of <Emphasis Type="Italic">Azospirillum</Emphasis> lectins on β-glucosidase activity

Lectins from the surface of Azospirillum brasilense Sp7 and Azospirillum brasilense Sp7.2.3 (a mutant with impaired lectin activity) were shown to induce a stabilizing effect on the activity of almond β-glucosidase under conditions of thermoinactivation and proteolytic enzyme treatment. Differences were revealed in the influence of lectins with various antigenic properties. Our results indicate that the effects of lectins on the catalytic activity of the enzyme are mainly associated with conformational changes in lectin molecules during mutagenesis, but not with carbohydrate specificity (general property). These data should be taken into account in evaluating the role of lectins in the formation of nitrogen-fixing associations.     

Influence of divalent cations on the catalytic properties and secondary structure of unadenylylated glutamine synthetase from Azospirillum brasilense

Fully unadenylylated glutamine synthetase (GS) from the endophytic bacterium Azospirillum brasilense Sp245 was isolated and purified. The enzyme was electrophoretically homogeneous and contained strongly bound metal ions, which could not be removed by dialysis. Mn²⁺, Mg²⁺, and Co²⁺ were found to be effective in supporting biosynthetic activity of the A. brasilense GS. Some kinetic properties of Mn²⁺-activated and Mg²⁺-activated unadenylylated GS were characterized. Circular dichroism analysis of the enzyme showed that the A. brasilense GS is a highly structured protein: 59% of its residues form -helices and 13% -strands. Removal of the metal ions from the A. brasilense GS by treatment with EDTA resulted in alterations in the enzyme secondary structure.     

Effects of GNA and other mannose binding lectins on development and fecundity of the peach-potato aphid Myzus persicae

Three mannose-binding lectins were assayed in artificial diets for their toxic and growth-inhibitory effects on nymphal development of the peach-potato aphid Myzus persicae. The snowdrop (Galanthus nivalis) lectin GNA was the most toxic, with an induced nymphal mortality of 42% at 1500 g ml^–1 (30 M) and an IC₅₀ (50% growth inhibition) of 630 g ml^–1 (13 M). The daffodil (Narcissus pseudonarcissus) lectin NPA and a garlic (Allium sativum) lectin ASA induced no significant mortality in the range 10–1500 g ml^–1, but did result in growth inhibition of 59% (NPA) and 26% (ASA) at 1500 g ml^–1 (40 M for NPA, 63 M for ASA). All three lectins were responsible for a slight but significant growth stimulation when ingested at 10 g ml^–1, reaching +26%, +18% and +11% over the control values for the garlic lectin, the daffodil lectin and the snowdrop lectin, respectively. GNA, as well as the glucose/mannose binding lectin Concanavalin A, were also provided at sublethal doses throughout the life cycle of the aphids, and effects on adult performance were monitored. Adult survival was not significantly altered, but both lectins adversely affected total fecundity and the dynamics of reproduction, resulting in significant reduction in calculated r _ms (population intrinsic rate of natural increase) on lectin-containing diets. These effects are discussed in relation to the use of transgenic plants expressing these toxic lectins for potential control of aphid populations.     

Heterogeneity of apical glycoconjugates in kidney collecting ducts: Further studies using simultaneous detection of lectin binding sites and immunocytochemical detection of key transport enzymes

Summary In the search for a functional role for the polarized glycoconjugates of rat collecting duct epithelial cells, the relation between binding of various lectins and expression of cellular transport enzyme profile of the cells was studied. For this purpose, principal and intercalated cells of rat kidney collecting duct were identified by morphological criteria and by their immunocytochemically determined content of (Na⁺+K⁺)-ATPase and carbonic anhydrase (CA II), respectively. VariousN-acetylgalactosamine-specific lectins such as those fromHelix pomatia andMaclura pomifera revealed heterogeneity among both principal and intercalated cells, whereas -N-acetylgalactosa nine-specific lectin fromDolichos biflorus andVicia villosa bound preferentially to principal cells. Still another lectin fromArachis hypogaea reacted with most collecting duct cells in the cortex and outer medulla, but only with a subpopulation of cells in the inner medulla. Interestingly, some lectins reacted exclusively with the apical aspect of the collecting duct epithelial cells, whereas others revealed both an apical and basolateral distribution of lectin reactive glycoconjugates. The results thus show subtle differences in the glycocalyx structure of principal and intercalated cells and differences in the intracellular polarization of glycoconjugates of these cells. Thus, lectins may be useful tools in the study of the molecular mechanisms which establish and maintain the polarized functions of principal and intercalated cells.     

Synthesis, Characterization and Antitumor Studies of Mn(II), Ni(II), Cu(II) and Zn(II) Complexes of N-Nicotinoyl-N′-o-Hydroxythiobenzhydrazide

A new ligand N-Nicotinoyl-N-o-hydroxythiobenzhydrazide (H₂Notbh) forms complexes [Mn(Notbh)(H₂O)], [M(Notbh)] [M=Ni(II) Cu(II) and Zn(II)] which were characterized by various physico-chemical techniques. All the metal complexes were observed to inhibit the growth of tumor in vitro, whereas, ligand did not. In vivo administration of these complexes resulted in prolongation of survival of tumor bearing mice. Tumor bearing mice administered with metal complexes showed reversal of tumor growth associated induction of apoptosis in lymphocytes. The paper discusses the possible mechanisms and therapeutic implication of the H₂Notbh and its metal complexes in tumor regression and tumor growth associated immunosuppression.     

Characterization of theGeosiphon pyriforme symbiosome by affinity techniques: confocal laser scanning microscopy (CLSM) and electron microscopy

Summary Geosiphon pyriforme represents a photoautotrophic endosymbiosis of aGlomus-like fungus with the cyanobacteriumNostoc punctiforme. The fungus forms unicellular bladders of up to 2 mm in length and 0.5 mm in diameter growing on the soil surface and harboring the endosymbioticNostoc filaments. The cyanobacteria are located in a compartment (the symbiosome) bordered by a host membrane. The space between this symbiosome membrane (SM) and theNostoc cell wall is filled with an about 30–40 nm thick layer of amorphous material, which is present also in the regions of the symbiosome where noNostoc filaments are located. At these sites the amorphous material consists of a 20–30 nm thick layer separating the SM. The region between the SM and the cyanobacterium is defined as symbiosome space (SS). Fungal bladders, hyphae and free livingNostoc were analyzed by affinity techniques as well as the material occurring in the SS. FITC-coupled lectins with sugar specificity to -D-mannosyl/-D-glucosyl (Con A), N-acetyl--D-glucosamine oligomers (WGA), -L-fucosyl (UEA-I), -D-galactosyl (RCA-120), -D-galactosyl (BS-I-B₄), N-acetyl--D-galactosamine (HPA), and sialic acid (EBL) residues were tested. WGA binding and calcofluor white staining demonstrated that the bladder wall as well as the SS contain fibrillar chitin. Of the other lectins only Con A clearly labeled the symbiosome. On the contrary, the lectin binding properties of the slime produced by free livingNostoc-colonies indicate the presence of mannose, fucose, GalNAc, sialic acid, and galactose, while chitin or GlucNAc-oligomers could not be detected. The symbiosome was also investigated electron microscopically. WGA-gold binding confirmed the presence of chitin, while a slight PATAg reaction indicated some polysaccharidic molecules within the SS. Our results show that the amorphous material within the SS contains molecules typical of the fungal cell wall and suggest that the SM is related to the fungal plasma membrane. The applied lectins all bind to the hyphal surface, indicating a high molecular complexity. Mannosyl, -galactosyl, and sialic acid residues are strongly exposed at the outer cell wall layer, whereas GlucNAc, GalNAc, and -galactosyl residues seem to be present in smaller amounts. The symbiotic interface established between the fungus andNostoc inGeosiphon shows many similarities to that occurring between fungi and root cells in arbuscular mycorrhizas.Abbreviations AM arbuscular mycorrhiza - BS-I-B₄ Bandeiraea simplicifolia lectin I isolectin B₄ - CLSM confocal laser scanning microscopy - Con A Concanavalin A - EBL elderberry bark lectin I - FITC fluorescein isothiocyanate - HPA Helix pomatia agglutinin - PATAg periodic acid-thiocarbohydrazide-Ag proteinate - SM symbiosome membrane - SS symbiosome space - RCA-120 Ricinus communis agglutinin 120 - UEA-I Ulex europaeus agglutinin I - WGA wheat germ agglutinin Dedicated to Professor Dr. Peter Sitte at the occasion of his 65th birthday     

Characterization of the binding specificity ofAnguilla anguilla agglutinin (AAA) in comparison toUlex europaeus agglutinin I (UEA-I)

Using immunochemical and immunohistochemical methods, the binding site ofAnguilla anguilla agglutinin (AAA) was characterized and compared with the related fucose-specific lectin fromUlex europaeus (UEA-I). In solid-phase enzyme-linked immunoassays, the two lectins recognized Fuc1-2Gal-HSA. AAA additionally cross-reacted with neoglycolipids bearing lacto-N-fucopentaose (LNFP) I [H type 1] and II [Le^a] and lactodifucotetraose (LDFT) as glycan moieties. UEA-I, on the other hand, bound to a LDFT-derived neoglycolipid but not to the other neoglycolipids tested. Binding of AAA to gastric mucin was competitively neutralized by Le^a-specific monoclonal antibodies. UEA-I binding, on the other hand, was reduced after co-incubation with H type 2- and Le^y-specific monoclonal antibodies. According to our results, AAA reacts with fucosylated type 1 chain antigens, whereas UEA-I binds only to the 1-2-fucosylated LDFT-derived neoglycolipid. In immunohistochemical studies, the reactivity of AAA and UEA-I in normal pyloric mucosa from individuals with known Lewis and secretor status was analysed. AAA showed a broad reaction in the superficial pyloric mucosa from secretors and non-secretors, but AAA reactivity was more pronounced in Le^(a+b-) individuals. On the other hand, UEA-I stained the superficial pyloric mucosa only from secretor individuals. A staining of deep mucous glands by the lectins was found in all specimens. Both reacted with most human carcinomas of different origin. Slight differences in their binding pattern were observed and may be explained by the different fine-specificities of the lectins.     

Dynamics of the changes of electrophysical properties of <Emphasis Type="Italic">Azospirillum brasilense</Emphasis> Sp7 cells at their binding with wheat germ agglutinin

The electrooptical properties of Azospirillum brasilense Sp7 cell suspensions, have been studied at a specific interaction with wheat germ agglutinin (WGA), using the dependences between the changes of optical densities of cell suspensions at the electric orientation of cells and the orienting field frequencies of 740, 1000, 1450, 2000, and 2800 kHz. It was shown that the electrooptical (EO) properties of cell suspensions changed at the interaction of A. brasilense Sp7 cells with WGA and that the EO signal value changed irrespective of the cultivation conditions. At the same time, the dynamics of the changes of the EO properties of microbial suspensions was different for microbial cells grown under different conditions. It may be evidence of the differences in the cell surface properties of microbial cells, and of the dependence, between bacterial response to lectin and growth conditions. The possibility of using the EO analysis of bacterial suspensions for the study of the high-specific binding of polypeptide molecular signals with the bacterial target cells and for assessment of the dynamics of this process has been demonstrated.     

The monoclonal antibody,anti-asialoglycophorin from human erythrocytes,specific forβ-d-Gal-1-3-α-d-GalNAc-chains (Thomsen-Friedenreich receptors)

The monoclonal antibody 22.19 of IgM class obtained after immunization of BALB/c mice with asialoglycophorin of human erythrocyte membranes is described. The specificity of this antibody for -d-Gal-1-3--d-GalNAc- disaccharide chains (Thomsen-Friedenreich receptors) was established by studying its reactivity against various erythrocytes, glycoproteins and oligosaccharides and by comparison with two lectins, peanut agglutinin andVicia graminea lectin, which recognize these disaccharide chains.Abbreviations PNA peanut agglutinin - VgL Vicia graminea lectin - TF Thomsen-Friedenreich - HSA human serum albumin - MoAb monoclonal antibody     

Saccharide binding to three Gal/GalNAc specific lectins: Fluorescence,spectroscopic and stopped-flow kinetic studies

Fluorescence and stopped-flow spectrophotometric studies on three plant lectins fromPsophocarpus tetragonolobus (winged bean),Glycine max (soybean) andArtocarpus integrifolia (jack fruit) have been studied usingN-dansylgalactosamine as a fluorescent ligand. The best monosaccharide for the winged bean agglutinin I (WBA I) and soybean (SBA) is Me-GalNAc and for jack fruit agglutinin (JFA) is Me-Gal. Examination of the percentage enhancement and association constants (1.51×10⁶, 6.56×10⁶ and 4.17×10⁵ M^–1 for SBA, WBA I and JFA, respectively) suggests that the combining regions of the lectins SBA and WBA I are apolar whereas that of JFA is polar. Thermodynamic parameters obtained for the binding of several monosaccharides to these lectins are enthalpically favourable. The binding of monosaccharides to these lectins suggests that the-OH groups at C-1, C-2, C-4 and C-6 in thed-galactose configuration are important loci for interaction with these lectins. An important finding is that the JFA binds specifically to Galß1-3GaINAc with much higher affinity than the other disaccharides which are structurally and topographically similar.The results of stopped-flow spectrometry on the binding ofN-dansylgalactosamine to these lectins are consistent with a bimolecular single step mechanism. The association rate constants (2.4×10⁵, 1.3×10⁴, and 11.7×10⁵ M^–1 sec^–1 for SBA, WBA I and JFA, respectively) obtained are several orders of magnitude slower than the ones expected for diffusion controlled reactions. The dissociation rate constants (0.2, 3.2×10^–2, 83.3 sec^–1 for SBA, WBA I and JFA, respectively) obtained for the dissociation ofN-dansylgalactosamine from its lectin complex are slowest for SBA and WBA I when compared with any other lectin-ligand dissociation process.Abbreviations SBA Soybean agglutinin - WBA I Winged bean agglutinin (Basic) - JFA Jack fruit agglutinin - PNA Peanut agglutinin - Con A Concanavalin A - Dansyl (Dns) 5-dimethylaminonaphthalene-I-sulphonyl - 2GaINDns N-dansylgalactosamine - dGal 2-deoxygalactose - l-Ara l-arabinose - d-Fuc d-fucose - l-Rha l-rhamnose - N-acetyllactosamine Galß4GlcNAc - melibiose Gal6Glc