Multivalent ligand binding by serum mannose-binding protein

Mannose-binding lectin conjugated to quantum dots as fluorescent nanotools for carbohydrate tracing

Quantum dots (QDs) have stood out as nanotools for glycobiology due to their photostability and ability to be combined with lectins. Mannose-binding lectin (MBL) is involved in the innate immune system and plays important roles in the activation of the complement cascade, opsonization, and elimination of apoptotic and microbial cells. Herein, adsorption and covalent coupling strategies were evaluated to conjugate QDs to a recombinant human MBL (rhMBL). The most efficient nanoprobe was selected by evaluating the conjugate ability to labelCandida albicansyeasts by flow cytometry. The QDs-rhMBL conjugate obtained by adsorption at pH 6.0 was the most efficient, labelingca.100% of cells with the highest median fluorescence intensity. The conjugation was also supported by Fourier transform infrared spectroscopy, zeta potential, and size analyses.C. albicanslabeling was calcium-dependent; 12% and <1% of cells were labeled in buffers without calcium and containing EDTA, respectively. The conjugate promoted specific labeling (based on cluster effect) since, after inhibition with mannan, there was a reduction of 80% in cell labeling, which did not occur with methyl-α-D-mannopyranoside monosaccharide. Conjugates maintained colloidal stability, bright fluorescence, and biological activity for at least 8 months. Therefore, QDs-rhMBL conjugates are promising nanotools to elucidate the roles of MBL in biological processes.

Association of MBL-2 gene polymorphisms with systemic lupus erythematosus: an updated meta-analysis and trial sequential analysis

OBJECTIVES

Mannose-binding lectin (MBL), an essential innate immune molecule, enhances the opsonization process and activates the complement system. Genetic variations at the promoter and coding region of the MBL-2 gene have been associated with susceptibility to systemic lupus erythematosus (SLE); however, reports remained inconsistent. The present study performs a meta-analysis of published peer-reviewed articles to draw a definitive conclusion.

MATERIALS AND METHODS

Published peer-reviewed articles on the association of MBL-2 gene polymorphisms and SLE were screened on various databases such as PubMed (Medline), ScienceDirect, and Google Scholar. A total of 23 eligible articles were included in the present study, comprising 3074 SLE patients and 3985 controls. Genotype and/or allele data for MBL-2 polymorphisms (A > B, A > C, A > D, A > O, Y > X and H > L) were extracted and analyzed by Comprehensive Meta-Analysis software (CMA V3.1).

RESULTS

The overall analysis revealed a significant association of MBL-2 (A > O) polymorphism with a predisposition to SLE in allele contrast (p = 0.000; OR = 1.261), homozygous (p = 0.005; OR = 1.482), heterozygous (p = 0.004; OR = 1.247), dominant (p = 0.000; OR = 1.303) and recessive (p = 0.025; OR = 1.356) genetic comparison model. Similar results were also observed in the comparison of allele and the dominant genetic model of MBL-2 (A > B) polymorphism in overall (allele: p = 0.000, OR = 1.46, dominant: p = 0.001, OR = 1.31) and in the Asian cohorts (allele: p = 0.007, OR = 1.43, dominant: p = 0.008, OR = 1.32). Interestingly, MBL-2 (Y-221X) polymorphism exhibited protection against the development of SLE in heterozygous (p = 0.005, OR = 0.619) and dominant genetic comparison (p = 0.01, OR = 0.672) models.

CONCLUSIONS

MBL-2 variants (A > O and A > B) are associated with predisposition to SLE. Conversely, promoter polymorphism (Y-221X) offers protection against SLE development.

Mannose-binding lectin 2 (Mbl2) gene polymorphisms are related to protein plasma levels, but not to heart disease and infection by Chlamydia

The presence of the single nucleotide polymorphisms in exon 1 of the mannose-binding lectin 2 (MBL2) gene was evaluated in a sample of 159 patients undergoing coronary artery bypass surgery (71 patients undergoing valve replacement surgery and 300 control subjects) to investigate a possible association between polymorphisms and heart disease with Chlamydia infection. The identification of the alleles B and D was performed using real time polymerase chain reaction (PCR) and of the allele C was accomplished through PCR assays followed by digestion with the restriction enzyme. The comparative analysis of allelic and genotypic frequencies between the three groups did not reveal any significant difference, even when related to previous Chlamydia infection. Variations in the MBL plasma levels were influenced by the presence of polymorphisms, being significantly higher in the group of cardiac patients, but without representing a risk for the disease. The results showed that despite MBL2 gene polymorphisms being associated with the protein plasma levels, the polymorphisms were not enough to predict the development of heart disease, regardless of infection with both species of Chlamydia.

Shape Effect of Glyco-Nanoparticles on Macrophage Cellular Uptake and Immune Response

The shells of various poly(dl-lactide)-b-poly(acrylic acid) (PDLLA-b-PAA) spherical micelles and poly(l-lactide)-b-poly(acrylic acid) (PLLA-b-PAA) cylindrical micelles were functionalized with mannose to yield glyco-nanoparticles (GNPs) with different shapes and dimensions. All of these GNPs were shown to have good biocompatibility (up to 1 mg/mL). Cellular uptake experiments using RAW 264.7 have shown that the spherical GNPs were internalized to a much greater extent than the cylindrical GNPs and such a phenomenon was attributed to their different endocytosis pathways. It was demonstrated that spherical GNPs were internalized based on clathrin- and caveolin-mediated endocytosis while cylindrical GNPs mainly depended on clathrin-mediated endocytosis. We also found that longer cylindrical GNPs (Ln × Wn = 215 × 47 nm) can induce an inflammatory response (specifically interleukin 6) more efficiently than shorter cylindrical GNPs (Ln × Wn = 99 × 50 nm) and spherical GNPs (Dn = 46 nm).

Bi- to tetravalent glycoclusters presenting GlcNAc/GalNAc as inhibitors: from plant agglutinins to human macrophage galactose-type lectin (CD301) and galectins

Emerging insights into the functional spectrum of tissue lectins leads to identification of new targets for the custom-made design of potent inhibitors, providing a challenge for synthetic chemistry. The affinity and selectivity of a carbohydrate ligand for a lectin may immensely be increased by a number of approaches, which includes varying geometrical or topological features. This perspective leads to the design and synthesis of glycoclusters and their testing using assays of physiological relevance. Herein, hydroquinone, resorcinol, benzene-1,3,5-triol and tetra(4-hydroxyphenyl)ethene have been employed as scaffolds and propargyl derivatives obtained. The triazole-containing linker to the α/β-O/S-glycosides of GlcNAc/GalNAc presented on these scaffolds was generated by copper-catalysed azide-alkyne cycloaddition. This strategy was used to give a panel of nine glycoclusters with bi-, tri- and tetravalency. Maintained activity for lectin binding after conjugation was ascertained for both sugars in solid-phase assays with the plant agglutinins WGA (GlcNAc) and DBA (GalNAc). Absence of cross-reactivity excluded any carbohydrate-independent reactivity of the bivalent compounds, allowing us to proceed to further testing with a biomedically relevant lectin specific for GalNAc. Macrophage galactose(-binding C)-type lectin, involved in immune defence by dendritic cells and in virus uptake, was produced as a soluble protein without/with its α-helical coiled-coil stalk region. Binding to ligands presented on a matrix and on cell surfaces was highly susceptible to the presence of the tetravalent inhibitor derived from the tetraphenylethene-containing scaffold, and presentation of GalNAc with an α-thioglycosidic linkage proved favorable. Cross-reactivity of this glycocluster to human galectins-3 and -4, which interact with Tn-antigen-presenting mucins, was rather small. Evidently, the valency and spatial display of α-GalNAc residues is a key factor to design potent and selective inhibitors for this lectin.

Effects of single N-glycosylation site knockout on folding and defibrinogenating activities of acutobin recombinants from HEK293T

Acutobin, the α-fibrinogenase from Deinagkistrodon acutus venom, contains four N-glycosylation sites with disialylated complex-typed glycans. Here, we explore the functional roles of each of the N-glycan by site-directed mutagenesis. The wild-type (ATB-wt) and single glycan-knockout mutants of recombinant acutobin were prepared from HEK293T, demonstrating that mutations at Asn(77), Asn(81) and Asn(100) impaired the folding while the S79A mutant and various Asn(229)-deglycosylated mutants were correctly folded. Based on homology modeling of acutobin and multiple sequence alignment with various venom thrombin-like enzymes, the importance of a hydrophilic environment at each glycosylation site to the enzyme folding could be rationalized. Remarkably, all the mutants showed similar catalytic activities for the chromogenic substrate and similar thermal stabilities as ATB-wt, suggesting that the glycan knockout did not affect the gross conformation and stability of the active sites. Although SDS-PAGE analyses revealed that ATB-wt and the D229-mutant degraded all human fibrinogen subunits faster but less specifically in vitro as compared with other mutants that cleaved only the α-subunit, ATB-wt and D229-mutant were not able to release fibrinogen-peptide A and thus coagulated human plasma slower than the other mutants did. In the mice model, the defibrinogenating effect of ATB-wt was stronger and lasting-longer than those of all the mutants. Taken together, all the glycans contribute to the pharmacokinetics of acutobin and ATB-wt in vivo, and the microenvironment around the Asn(229)-glycan appears to regulate the fibrinogen-chain specificity of acutobin while the N-glycans at positions 77, 81 and 100 are crucial for its folding.

Correlation between the glycan variations and defibrinogenating activities of acutobin and its recombinant glycoforms

Acutobin isolated from Deinagkistrodon acutus venom has been used to prevent or treat stroke in patients. This defibrinogenating serine protease is a 39 kDa glycoprotein containing terminal disialyl-capped N-glycans. After sialidase treatment, the enzyme showed similar catalytic activities toward chromogenic substrate, and cleaved the Aα chain of fibrinogen as efficiently as the native acutobin did. However, the level of fibrinogen degradation products in mice after i.p.-injection of desialylated-acutobin was significantly lower than the level after acutobin injection, suggesting that the disialyl moieties may improve or prolong the half-life of acutobin. Two recombinant enzymes with identical protein structures and similar amidolytic activities to those of native acutobin were expressed from HEK293T and SW1353 cells and designated as HKATB and SWATB, respectively. Mass spectrometric profiling showed that their glycans differed from those of acutobin. In contrast to acutobin, HKATB cleaved not only the Aα chain but also the Bβ and γ chains of human fibrinogens, while SWATB showed a reduced α-fibrinogenase activity. Non-denaturing deglycosylation of these proteases by peptide N-glycosidase F significantly reduced their fibrinogenolytic activities and thermal stabilities. The in vivo defibrinogenating effect of HKATB was inferior to that of acutobin in mice. Taken together, our results suggest that the conjugated glycans of acutobin are involved in its interaction with fibrinogen, and that the selection of cells optimally expressing efficient glycoforms and further glycosylation engineering are desirable before a recombinant product can replace the native enzyme for clinical use.

First evidence of protein G-binding protein in the most primitive vertebrate: serum lectin from lamprey (Lampetra japonica)

The intelectins, a recently identified subgroup of extracellular animal lectins, are glycan-binding receptors that recognize glycan epitopes on foreign pathogens in host systems. Here, we have described NPGBP (novel protein G-binding protein), a novel serum lectin found in the lamprey, Lampetra japonica. RT-PCR yielded a 1005 bp cDNA sequence from the lamprey liver encoding a 334 amino acid secretory protein with homology to mammalian and aquatic organism intelectins. Gene expression analyses showed that the NPGBP gene was expressed in the blood, intestines, kidney, heart, gill, liver, adipose tissue and gonads. NPGBP was isolated by protein G-conjugated agarose immunoprecipitation, and SDS-PAGE analyses showed that NPGBP migrated as a specific band (∼35 and ∼124 kDa under reducing and non-reducing conditions, respectively). These results suggested that NPGBP forms monomers and tetramers. NPGBP gene expression was induced by in vivo bacterial stimulation, and NPGBP showed different agglutination activities against pathogenic Gram-positive bacteria, Gram-negative bacteria and fungi. The induction of NPGBP suggested that it plays an important role in defense against microorganisms in the internal circulation system of the lamprey. When incubated with an unrelated antibody, the specific binding between NPGBP and protein G was competitively inhibited, indicating that NPGBP and the Fc region of Ig bind to the same site on protein G. We thus assume that the tertiary structure of NPGBP is similar to that of the Fc region of Ig. Additionally, NPGBP can effectively promote endothelial cell mitosis. These findings suggest that NPGBP plays a role in the immune defense against microorganisms, and this study represents one of the few examples of the characterization and functional analysis of an aquatic organism intelectin.

Identification and Characterization of a Novel Human Collectin CL-K1

Collectins are a family of C-type lectins with two characteristic structures, collagen like domains and carbohydrate recognition domains. They recognize carbohydrate antigens on microorganisms and act as host-defense. Here we report the cloning and characterization of a novel collectin CL-K1. RT-PCR analyses showed CL-K1 mRNA is present in all organs. The deduced amino acid sequence and the data from immunostaining of CL-K1 cDNA expressing CHO cells revealed that CL-K1 is expressed as a secreted protein. CL-K1 is found in blood by immunoblotting and partial amino acid analyses. CL-K1 showed Ca(2+)-dependent sugar binding activity of fucose and weakly mannose but not N-acetyl-galactosamine, N-acetyl-glucosamine, or maltose, though mannose-binding lectin (MBL) containing similar amino acid motif. CL-K1 can recognize specially several bacterial saccharides due to specific sugar-binding character. Elucidation of the role of two ancestor collectins of CL-K1 and CL-L1 could lead to see the biological function of collectin family.

In vivo targeting of alveolar macrophages via RAFT-based glycopolymers

Targeting cell populations via endogenous carbohydrate receptors is an appealing approach for drug delivery. However, to be effective, this strategy requires the production of high affinity carbohydrate ligands capable of engaging with specific cell-surface lectins. To develop materials that exhibit high affinity towards these receptors, we synthesized glycopolymers displaying pendent carbohydrate moieties from carbohydrate-functionalized monomer precursors via reversible addition-fragmentation chain transfer (RAFT) polymerization. These glycopolymers were fluorescently labeled and used to determine macrophage-specific targeting both in vitro and in vivo. Mannose- and N-acetylglucosamine-containing glycopolymers were shown to specifically target mouse bone marrow-derived macrophages (BMDMs) in vitro in a dose-dependent manner as compared to a galactose-containing glycopolymer (30- and 19-fold higher uptake, respectively). In addition, upon macrophage differentiation, the mannose glycopolymer exhibited enhanced uptake in M2-polarized macrophages, an anti-inflammatory macrophage phenotype prevalent in injured tissue. This carbohydrate-specific uptake was retained in vivo, as alveolar macrophages demonstrated 6-fold higher internalization of mannose glycopolymer, as compared to galactose, following intratracheal administration in mice. We have shown the successful synthesis of a class of functional RAFT glycopolymers capable of macrophage-type specific uptake both in vitro and in vivo, with significant implications for the design of future targeted drug delivery systems.

High affinity sialoside ligands of myelin associated glycoprotein

Myelin associated glycoprotein (Siglec-4) is a myelin adhesion receptor, that is, well established for its role as an inhibitor of axonal outgrowth in nerve injury, mediated by binding to sialic acid containing ligands on the axonal membrane. Because disruption of myelin-ligand interactions promotes axon outgrowth, we have sought to develop potent ligand based inhibitors using natural ligands as scaffolds. Although natural ligands of MAG are glycolipids terminating in the sequence NeuAcα2-3Galβ1-3(±NeuAcα2-6)GalNAcβ-R, we previously established that synthetic O-linked glycoprotein glycans with the same sequence α-linked to Thr exhibited ∼1000-fold increased affinity (∼1μM). Attempts to increase potency by introducing a benzoylamide substituent at C-9 of the α2-3 sialic acid afforded only a two-fold increase, instead of increases of >100-fold observed for other sialoside ligands of MAG. Surprisingly, however, introduction of a 9-N-fluoro-benzoyl substituent on the α2-6 sialic acid increased affinity 80-fold, resulting in a potent inhibitor with a K(d) of 15nM. Docking this ligand to a model of MAG based on known crystal structures of other siglecs suggests that the Thr positions the glycan such that aryl substitution of the α2-3 sialic acid produces a steric clash with the GalNAc, while attaching an aryl substituent to the other sialic acid positions the substituent near a hydrophobic pocket that accounts to the increase in affinity.

Pichia pastoris-produced mucin-type fusion proteins with multivalent O-glycan substitution as targeting molecules for mannose-specific receptors of the immune system

Mannose-binding proteins like the macrophage mannose receptor (MR), the dendritic cell-specific intercellular adhesion molecule-3 grabbing non-integrin (DC-SIGN) and mannose-binding lectin (MBL) play crucial roles in both innate and adaptive immune responses. Immunoglobulin fusion proteins of the P-selectin glycoprotein ligand-1 (PSGL-1/mIgG(2b)) carrying mostly O-glycans and, as a control, the α1-acid glycoprotein (AGP/mIgG(2b)) carrying mainly N-linked glycans were stably expressed in the yeast Pichia pastoris. Pichia pastoris-produced PSGL-1/mIgG(2b) was shown to carry O-glycans that mediated strong binding to mannose-specific lectins in a lectin array and were susceptible to cleavage by α-mannosidases including an α1,2- but not an α1,6-mannosidase. Electrospray ionization ion-trap mass spectrometry confirmed the presence of O-glycans containing up to nine hexoses with the penta- and hexasaccharides being the predominant ones. α1,2- and α1,3-linked, but not α1,6-linked, mannose residues were detected by (1)H-nuclear magnetic resonance spectroscopy confirming the results of the mannosidase cleavage. The apparent equilibrium dissociation constants for binding of PNGase F-treated mannosylated PSGL-1/mIgG(2b) to MR, DC-SIGN and MBL were shown by surface plasmon resonance to be 126, 56 and 16 nM, respectively. In conclusion, PSGL-1/mIgG(2b) expressed in P. pastoris carried O-glycans mainly comprised of α-linked mannoses and with up to nine residues. It bound mannose-specific receptors with high apparent affinity and may become a potent targeting molecule for these receptors in vivo.

Synthesis of dodecavalent fullerene-based glycoclusters and evaluation of their binding properties towards a bacterial lectin

Multivalency is playing a major role in biological processes and particularly in lectin-carbohydrate interactions. The design of high-affinity ligands of lectins should provide molecules capable of interfering with these biological processes and potentially inhibit bacterial or viral infections. Azide-alkyne "click" chemistry was applied to the synthesis of dodecavalent fullerene-based glycoclusters. The conjugation could be efficiently performed from alkyne or azide functions on either partners (i.e. hexakis-fullerene adduct or glycoside). PA-IL is a bacterial lectin from the opportunistic pathogen Pseudomonas aeruginosa and is involved in the recognition of glycoconjugates on human tissues. The glycoclusters obtained were evaluated as ligands of PA-IL and for their potential for competing with its binding to glycosylated surfaces. The affinities measured by hemagglutination inhibition assay (HIA), enzyme-linked lectin assay (ELLA), and surface plasmon resonance (SPR) displayed a significant "glycoside cluster effect" with up to a 12,000-fold increase in binding when comparing a monovalent carbohydrate reference probe with a dodecavalent fullerene-based glycocluster, albeit with some differences depending on the analytical technique.

Selectivity among two lectins: probing the effect of topology, multivalency and flexibility of "clicked" multivalent glycoclusters

The design of multivalent glycoconjugates has been developed over the past decades to obtain high-affinity ligands for lectin receptors. While multivalency frequently increases the affinity of a ligand for its lectin through the so-called "glycoside cluster effect", the binding profiles towards different lectins have been much less investigated. We have designed a series of multivalent galactosylated glycoconjugates and studied their binding properties towards two lectins, from plant and bacterial origins, to determine their potential selectivity. The synthesis was achieved through copper(I)-catalysed azide-alkyne cycloaddition (CuAAC) under microwave activation between propargylated multivalent scaffolds and an azido-functionalised carbohydrate derivative. The interactions of two galactose-binding lectins from Pseudomonas aeruginosa (PA-IL) and Erythrina cristagalli (ECA) with the synthesized glycoclusters were studied by hemagglutination inhibition assays (HIA), surface plasmon resonance (SPR) and isothermal titration microcalorimetry (ITC). The results obtained illustrate the influence of the scaffold's geometry on the affinity towards the lectin and also on the relative potency in comparison with a monovalent galactoside reference probe.

Identification, cloning and tissue localization of a rainbow trout (Oncorhynchus mykiss) intelectin-like protein that binds bacteria and chitin

Intelectins are a recently identified group of animal lectins involved in innate immune surveillance. This paper describes the primary structure, expression and immunohistochemical localization of a rainbow trout plasma intelectin (RTInt). RTInt exhibited calcium-dependent binding to N-acetylglucosamine (GlcNAc) and mannose conjugated Toyopearl Amino 650 M matrices. When GlcNAc eluates from chromatography matrices were analyzed by reducing 1D PAGE and Western blots, the lectin appeared as approximately 37 kDa and approximately 72 kDa bands. Similar analysis of plasma revealed a single 72 kDa band under reducing conditions. MALDI-TOF MS demonstrated five, approximately 37 kDa isoforms (pI 5.3-6.1) separated by 2D-PAGE. A 975 bp cDNA sequence obtained by RT-PCR from liver and spleen tissue encoded a 325 amino acid secretory protein with homology to human and murine intelectins, which bind bacterial components and are induced during parasitic infections. Gene expression and immunohistochemistry detected RTInt in gill, spleen, hepatic sinusoid, renal interstitium, intestine, skin, swim bladder and within leukocytes. Direct binding assays demonstrated the ability of RTInt to bind relevant bacterial and chitinous targets. These findings suggest that RTInt plays a role in innate immune defense against bacterial and chitinous microbial organisms.

Bacterial-binding activity and plasma concentration of ladderlectin in rainbow trout (Oncorhynchus mykiss)

Soluble, defense lectins bind conserved microbial patterns leading to pathogen opsonization, enhanced phagocytosis and activation of complement. These immune functions, however, vary widely among individuals due to genetic and acquired differences affecting binding capacity or plasma concentration. Most evidence for the defensive function of soluble lectins is based on mammals, but several functionally homologous, but less well-characterized, lectins have been identified in fish. In this study, we compared binding of rainbow trout plasma ladderlectin to relevant, intact bacterial targets. A polyclonal antiserum raised against a synthetic peptide identical to the 20 N-terminal amino acids of the reduced 16 kDa rainbow trout ladderlectin subunit was used to detect plasma ladderlectin in immunoblots and indirect enzyme-linked immunosorbent assay (ELISA). Ladderlectin binding to Aeromonas salmonicida subsp. salmonicida, Aeromonas hydrophila, Yersinia ruckeri and Pseudomonas sp. was detected by PAGE and immunoblots of saccharide elutions from intact bacteria incubated in the presence of normal trout plasma. Although plasma concentrations of immunoreactive ladderlectin were low in the majority of trout, significant (P < 0.0001) variation between individual fish was observed in two separate populations. In addition, one population demonstrated a subset of individuals whose ladderlectin levels were approximately seven-fold higher than the population median. These findings indicate that rainbow trout have variable amounts of plasma ladderlectin capable of binding to the surfaces of several relevant bacterial targets.

Comparative genetics and innate immune functions of collagenous lectins in animals

Collagenous lectins such as mannan-binding lectins (MBLs), ficolins (FCNs), surfactant proteins A and D (SP-A, SP-D), conglutinin (CG), and related ruminant lectins are multimeric proteins with carbohydrate-binding domains aligned in a manner that facilitates binding to microbial surface polysaccharides. MBLs and FCNs are structurally related to C1q, but activate the lectin complement pathway via interaction with MBL-associated serine proteases (MASPs). MBLs, FCNs, and other collagenous lectins also bind to some host macromolecules and contribute to their removal. While there is evidence that some lectins and the lectin complement pathway are conserved in vertebrates, many differences in collagenous lectins have been observed among humans, rodents, and other vertebrates. For example, humans have only one MBL but three FCNs, whereas most other species express two FCNs and two MBLs. Bovidae express CG and other SP-D-related collectins that are not found in monogastric species. Some dysfunctions of human MBL are due to single nucleotide polymorphisms (SNPs) that affect its expression or structure and thereby increase susceptibility to some infections. Collagenous lectins have well-established roles in innate immunity to various microorganisms, so it is possible that some lectin genotypes or induced phenotypes influence resistance to some infectious or inflammatory diseases in animals.

The two major oligomeric forms of human mannan-binding lectin: chemical characterization, carbohydrate-binding properties, and interaction with MBL-associated serine proteases

Mannan-binding lectin (MBL) is an oligomeric C-type lectin assembled from homotrimeric structural units that binds to neutral carbohydrates on microbial surfaces. It forms individual complexes with MBL-associated serine proteases (MASP)-1, -2, -3 and a truncated form of MASP-2 (MAp19) and triggers the lectin pathway of complement through MASP-2 activation. To characterize the oligomerization state of the two major MBL forms present in human serum, both proteins were analyzed by mass spectrometry. Mass values of 228,098 +/- 170 Da (MBL-I) and 304,899 +/- 229 Da (MBL-II) were determined for the native proteins, whereas reduction of both species yielded a single chain with an average mass of 25,340 +/- 18 Da. This demonstrates that MBL-I and -II contain 9 and 12 disulfide-linked chains, respectively, and therefore are trimers and tetramers of the structural unit. As shown by surface plasmon resonance spectroscopy, trimeric and tetrameric MBL bound to immobilized mannose-BSA and N-acetylglucosamine-BSA with comparable K(D) values (2.2 and 0.55 nM and 1.2 and 0.96 nM, respectively). However, tetrameric MBL exhibited significantly higher maximal binding capacity and lower dissociation rate constants for both carbohydrates. In contrast, no significant difference was detected for binding of the recombinant MASPs or MAp19 to immobilized trimeric or tetrameric MBL. As shown by gel filtration, both MBL species formed 1:2 complexes with MASP-3 or MAp19. These results provide the first precise analysis of the major human MBL oligomers. The oligomerization state of MBL has a direct effect on its carbohydrate-binding properties, but no influence on the interaction with the MASPs.

Proteins that bind high-mannose sugars of the HIV envelope

A broad range of proteins bind high-mannose carbohydrates found on the surface of the envelope protein gp120 of the human immunodeficiency virus and thus interfere with the viral life cycle, providing a potential new way of controlling HIV infection. These proteins interact with the carbohydrate moieties in different ways. A group of them interacts as typical C-type lectins via a Ca2+ ion. Another group interacts with specific single, terminal sugars, without the help of a metal cation. A third group is involved in more intimate interactions, with multiple carbohydrate rings and no metal ion. Finally, there is a group of lectins for which the interaction mode has not yet been elucidated. This review summarizes, principally from a structural point of view, the current state of knowledge about these high-mannose binding proteins and their mode of sugar binding.

Characterization of Oligosaccharide Ligands Expressed on SW1116 Cells Recognized by Mannan-binding Protein

Mannan-binding protein (MBP) is a C-type serum lectin and activates complement through the lectin pathway when it binds to ligand sugars such as mannose, N-acetylglucosamine, and fucose on microbes. In addition, the vaccinia virus carrying the human MBP gene was shown to exhibit potent growth inhibitory activity toward human colorectal carcinoma, SW1116, cells in nude mice. We have proposed calling this activity MBP-dependent cell-mediated cytotoxicity (MDCC) (Ma, Y., Uemura, K., Oka, S., Kozutsumi, Y., Kawasaki, N., and Kawasaki, T. (1999) Proc. Natl. Acad. Sci. U. S. A. 96, 371-375). In this study, the MBP ligands on the surface of SW1116 cells were characterized. Initial experiments involving plant lectins and anti-Lewis antibodies as inhibitors of MBP binding to SW1116 cells indicated that fucose plays a crucial role in the interaction. Subsequently, Pronase glycopeptides were prepared from whole cell lysates, and oligosaccharides were liberated by hydrazinolysis. After being tagged by pyridylamination, MBP ligand oligosaccharides were isolated with an MBP affinity column, and then their sequences were determined by mass spectrometry and tandem mass spectrometry after permethylation, in combination with endo-beta-galactosidase digestion and chemical defucosylation. The MBP ligands were shown to be large, multiantennary N-glycans carrying a highly fucosylated polylactosamine type structure. At the nonreducing termini, Le(b)/Le(a) or tandem repeats of the Le(a) structure prevail, a substantial proportion of which are attached via internal Le(x) or N-acetyllactosamine units to the trimannosyl core. The structures characterized are unique and distinct from those of other previously reported tumor-specific carbohydrate antigens. It is concluded that MBP requires clusters of tandem repeats of the Le(b)/Le(a) epitope for recognition.

Inhibition of bovine sperm-oocyte fusion by the p-aminophenyl derivative of D-mannose

Several steps in the process of mammalian fertilization are mediated by carbohydrates. This study investigated the role of the p-aminophenyl derivative of d-mannose (APMP) during bovine fertilization. Inseminating cumulus-oocyte complexes (COCs) in the presence of increasing APMP concentrations resulted in a significant dose-dependent decrease of the fertilization rate (P < 0.05). No negative effect of 50 mM APMP on total sperm motility and progressive motility was found. Subsequently, the fertilization steps at which this blocking effect could be exerted were investigated, i.e., sperm penetration of the cumulus oophorus, sperm-zona binding, acrosome reaction, sperm-oolemma binding, and/or sperm-oocyte fusion. Inseminating cumulus-enclosed and cumulus-denuded oocytes in the presence of 50 mM APMP significantly decreased the fertilization rate to a comparable minimum level (P < 0.05). There was no significant relationship between the number of spermatozoa bound to the zona pellucida and the APMP concentration, and APMP nor d-mannosylated bovine serum albumin (BSA) suppressed or stimulated sperm acrosomal status. Inseminating zona-free oocytes in the presence of 50 mM APMP did not influence sperm-oolemma binding, but significantly inhibited sperm-oocyte fusion (P < 0.05). Preincubating zona-free oocytes with 200 microg/ml Con A but not with 50 mM APMP inhibited the sperm-oocyte fusion rate to the same extent as when the gametes were simultaneously exposed to 50 mM APMP. These data indicate that the blocking effect of APMP on bovine fertilization is mainly due to an inhibition of sperm-oocyte fusion, probably by specific obstruction of the sperm receptor sites that are responsible for the fusion process.

Human immunodeficiency virus envelope (gp120) binding to DC-SIGN and primary dendritic cells is carbohydrate dependent but does not involve 2G12 or cyanovirin binding sites: implications for structural analyses of gp120-DC-SIGN binding

The calcium-dependent lectin, DC-SIGN, binds to human immunodeficiency virus (HIV) (and simian immunodeficiency virus) gp120 and mediates the binding and transfer of HIV from monocyte-derived dendritic cells (MDDCs) to permissive T cells. However, it has been recently reported that DC-SIGN binding to HIV gp120 may be carbohydrate independent. Here, we formally demonstrate that gp120 binding to DC-SIGN and MDDCs is largely if not wholly carbohydrate dependent. Endo-beta-N-glucosaminidase H (EndoH) treatment of gp120-Fc under conditions that maintained wild-type CD4 binding-and the full complement of complex glycans-significantly decreased (>90%) binding to DC-SIGN expressing cell lines, as well as to MDDCs. Any residual binding of EndoH-treated gp120-Fc to DC-SIGN was completely competed off with mannan. Mutational analysis indicated that no single glycosylation site affected the ability of gp120-Fc to bind DC-SIGN. To further guide our efforts in mapping the DC-SIGN binding sites on gp120, we used two well-characterized HIV inhibitory agents (2G12 monoclonal antibody and cyanovirin) that bind to high-mannose sugars on gp120. We showed that 2G12 and DC-SIGN bound to nonoverlapping sites in gp120 because (i) 2G12 did not block soluble gp120 or virion binding to DC-SIGN, (ii) 2G12 bound to gp120-Fc that was prebound to cell surface DC-SIGN, and (iii) gp120-Fc mutants that lack glycosylation sites involved in 2G12's epitope were also fully capable of binding DC-SIGN. These data were substantiated by the inability of cyanovirin to block gp120-Fc binding to DC-SIGN. Cyanovirin has been shown to effectively compete for 2G12 binding to gp120. Indeed, high concentrations of cyanovirin dramatically enhanced gp120-Fc binding to cell surfaces in the presence or absence of DC-SIGN. We provide evidence that this enhancement may be due to cyanovirin's ability to bridge gp120 to mannosylated cell surface proteins. These results have implications for antiviral therapeutics and for ongoing efforts to finely map the glycan structures on gp120 responsible for DC-SIGN binding.

Disseminated candidiasis and hepatic malarial infection in mannose-binding-lectin-A-deficient mice

To examine the physiological functions of mannose-binding lectin A (MBL-A), we generated mice that were deficient in MBL-A and examined their susceptibilities to the microbial pathogens Candida albicans and Plasmodium yoelii, an accepted experimental malaria model in mouse. We found no differences in the survival rates and fungal burdens of wild-type and MBL-A(-/-) mice with disseminated C. albicans infection. The two mouse strains were also similar in their abilities to resist hepatic accumulation of P. yoelii parasites. We conclude that MBL-A deficiency does not alter resistance to disseminated candidiasis or initial hepatic invasion by P. yoelii.

Evidence for clustered mannose as a new ligand for hyaluronan- binding protein (HABP1) from human fibroblasts

We have earlier reported that overexpression of the gene encoding human hyaluronan-binding protein (HABP1) is functionally active, as it binds specifically with hyaluronan (HA). In this communication, we confirm the collapse of the filamentous and branched structure of HA by interaction with increasing concentrations of recombinant-HABP1 (rHABP1). HA is the reported ligand of rHABP1. Here, we show the affinity of rHABP1 towards D-mannosylated albumin (DMA) by overlay assay and purification using a DMA affinity column. Our data suggests that DMA is another ligand for HABP1. Furthermore, we have observed that DMA inhibits the binding of HA in a concentration-dependent manner, suggesting its multiligand affinity amongst carbohydrates. rHABP1 shows differential affinity towards HA and DMA which depends on pH and ionic strength. These data suggest that affinity of rHABP1 towards different ligands is regulated by the microenvironment.

A novel mechanism of carbohydrate recognition by the C-type lectins DC-SIGN and DC-SIGNR. Subunit organization and binding to multivalent ligands

DC-SIGN and DC-SIGNR are cell-surface receptors that mediate cell-cell interactions within the immune system by binding to intercellular adhesion molecule-3. The receptor polypeptides share 77% amino acid sequence identity and are type II transmembrane proteins. The extracellular domain of each comprises seven 23-residue tandem repeats and a C-terminal C-type carbohydrate-recognition domain (CRD). Cross-linking, equilibrium ultracentrifugation, and circular dichroism studies of soluble recombinant fragments of DC-SIGN and DC-SIGNR have been used to show that the extracellular domain of each receptor is a tetramer stabilized by an alpha-helical stalk. Both DC-SIGN and DC-SIGNR bind ligands bearing mannose and related sugars through the CRDs. The CRDs of DC-SIGN and DC-SIGNR bind Man(9)GlcNAc(2) oligosaccharide 130- and 17-fold more tightly than mannose, and affinity for a glycopeptide bearing two such oligosaccharides is increased by a further factor of 5- to 25-fold. These results indicate that the CRDs contain extended or secondary oligosaccharide binding sites that accommodate mammalian-type glycan structures. When the CRDs are clustered in the tetrameric extracellular domain, their arrangement provides a means of amplifying specificity for multiple glycans on host molecules targeted by DC-SIGN and DC-SIGNR. Binding to clustered oligosaccharides may also explain the interaction of these receptors with the gp120 envelope protein of human immunodeficiency virus-1, which contributes to virus infection.

In vivo recognition of mannosylated proteins by hepatic mannose receptors and mannan-binding protein

In vivo recognition of mannosylated proteins by hepatic mannose receptors and serum mannan-binding protein (MBP) was investigated in mice. After intravenous administration, all three different (111)In-mannosylated proteins were taken up mainly by liver, and uptake was saturated with increasing doses. (111)In-Man-superoxide dismutases and (111)In-Man(12)- and (111)In-Man(16)-BSA had simple dose-dependent pharmacokinetic profiles, whereas other derivatives ((111)In-Man(25)-, -Man(35)-, and -Man(46)-BSA and (111)In-Man-IgGs) showed slow hepatic uptake at <1 mg/kg. Purified MBP experiments in vitro indicated that these derivatives bind to MBP in serum after injection, which interferes with their hepatic uptake. To quantitatively evaluate these recognition properties in vivo, a pharmacokinetic model-based analysis was performed for (111)In-Man-BSAs, estimating some parameters, including the Michaelis-Menten constant of the hepatic uptake and the dissociation constant of MBP, which correlate to the affinity of Man-BSAs for mannose receptors and MBP, respectively. The dissociation constant of Man-BSA and MBP decreased dramatically with increasing density of mannose, but the Michaelis-Menten constant of hepatic uptake of Man-BSA was not so sensitive to the change in density. This suggests that the in vivo recognition of MBP has a stronger cluster effect than that of mannose receptors. Differences obtained here are due to the unique arrangement of carbohydrate recognition domains on each mannose-specific lectin available for mannosylated ligand recognition.

A keratin peptide inhibits mannose-binding lectin

Complement plays a significant role in mediating endothelial injury following oxidative stress. We have previously demonstrated that the lectin complement pathway (LCP), which is initiated by deposition of the mannose-binding lectin (MBL), is largely responsible for activating complement on endothelial cells following periods of oxidative stress. Identifying functional inhibitors that block MBL binding will be useful in characterizing the role of the LCP in disease models. The human cytokeratin peptide SFGSGFGGGY has been identified as a molecular mimic of N-acetyl-D-glucosamine (GlcNAc), a known ligand of MBL. Thus, we hypothesized that this peptide would specifically bind to MBL and functionally inhibit the LCP on endothelial cells following oxidative stress. Using a BIAcore 3000 optical biosensor, competition experiments were performed to demonstrate that the peptide SFGSGFGGGY inhibits binding of purified recombinant human MBL to GlcNAc in a concentration-dependent manner. Solution affinity data generated by BIAcore indicate this peptide binds to MBL with an affinity (K(D)) of 5 x 10(-5) mol/L. Pretreatment of human serum (30%) with the GlcNAc-mimicking peptide (10-50 microg/ml) significantly attenuated MBL and C3 deposition on human endothelial cells subjected to oxidative stress in a dose-dependent manner, as demonstrated by cell surface ELISA and confocal microscopy. Additionally, this decapeptide sequence attenuated complement-dependent VCAM-1 expression following oxidative stress. These data indicate that a short peptide sequence that mimics GlcNAc can specifically bind to MBL and functionally inhibit the proinflammatory action of the LCP on oxidatively stressed endothelial cells.

The mannan-binding-lectin pathway of the innate immune response

Dramatic progress has been achieved during the past year in our understanding of how the complement system is activated via the mannan-binding-lectin pathway. Surprising discoveries have changed our concepts of the complexes that are formed upon engagement of mannan-binding lectin with its serine proteases.

Enhanced accumulation of sialyl Lewis X-carboxymethylpullulan conjugate in acute inflammatory lesion

PURPOSE

E-selectin is a cell adhesion molecule that is specifically expressed in the inflammatory vascular endothelium in response to cytokines such as IL-1 beta and TNF-alpha, and interacts with specific ligands containing sialyl Lewis X (Neu5Ac alpha 2-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc-, SLex). In order to investigate the ability of E-selectin ligands to target the inflammatory site, the tissue distribution of carboxymethylpullulan (CMPul) modified with SLex was studied.

METHODS

CMPul conjugates with various saccharides containing SLex and monovalent SLex were intravenously administered to mice with ear edema induced by arachidonic acid, and their distributions to the inflamed ear and other tissues were studied. To determine the microdistributions of these compounds, the inflamed ear was subjected to microautoradiography.

RESULTS

After intravenous administration AUC0-24h of SLex-CMPul, which binds to E-selectin, in the inflamed ear was about 300-fold and 2.5-fold higher than that of monovalent SLex and CMPul conjugated with other saccharides, which can not serve as ligands for E-selectin. Microautoradiography also revealed SLex-CMPul accumulated at the microvessels in the inflammatory lesions.

CONCLUSIONS

SLex-CMPul was found to have the potential to target drugs to the inflammatory lesion.

Structure, processing and properties of surfactant protein A

Surfactant protein A (SP-A) is a highly ordered, oligomeric glycoprotein that is secreted into the airspaces of the lung by the pulmonary epithelium. The in vitro activities of protein suggest diverse roles in pulmonary host defense and surfactant homeostasis, structure and surface activity. Functional mapping of SP-A using directed mutagenesis has identified domains which interact with surfactant phospholipids, alveolar type II cells and microbes. Recently developed genetically manipulated animal models are beginning to clarify the critical physiological roles for SP-A in the normal lung, and in the pathophysiology of pulmonary disease.

Substructural specificity and polyvalent carbohydrate recognition by the Entamoeba histolytica and rat hepatic N-acetylgalactosamine/galactose lectins

Both the Entamoeba histolytica lectin, a virulence factor for the causative agent of amebiasis, and the mammalian hepatic lectin bind to N-acetylgalactosamine (GalNAc) and galactose (Gal) nonreducing termini on oligosaccharides, with preference for GalNAc. Polyvalent GalNAc-derivatized neoglycoproteins have >1000-fold enhanced binding affinity for both lectins (Adler,P., Wood,S.J., Lee,Y.C., Lee,R.T., Petri,W.A.,Jr. and Schnaar,R.L.,1995, J. Biol. Chem ., 270, 5164-5171). Substructural specificity studies revealed that the 3-OH and 4-OH groups of GalNAc were required for binding to both lectins, whereas only the E.histolytica lectin required the 6-OH group. Whereas GalNAc binds with 4-fold lower affinity to the E.histolytica lectin than to the mammalian hepatic lectin, galactosamine and N-benzoyl galactosamine bind with higher affinity to the E. histolytica lectin. Therefore, a synthetic scheme for converting polyamine carriers to poly-N-acyl galactosamine derivatives (linked through the galactosamine primary amino group) was developed to test whether such ligands would bind the E.histolytica lectin with high specificity and high affinity. Contrary to expectations, polyvalent derivatives including GalN6lys5, GalN4desmosine, GalN4StarburstTMdendrimer, and GalN8StarburstTMdendrimer demonstrated highly enhanced binding to the mammalian hepatic lectin but little or no enhancement of binding to the E.histolytica lectin. We propose that the mammalian hepatic lectin binds with greatest affinity to GalNAc "miniclusters," which mimic branched termini of N-linked oligosaccharides, whereas the E.histolytica lectin binds most effectively to "maxiclusters," which may mimic more widely spaced GalNAc residues on intestinal mucins.

Quantum-dye labeled proteins for glycobiology: a viable nonradioactive alternative tracer

Quantum dye (QD), a macrocyclic europium-chelate, developed as a cytological marker, has never been used for quantitative applications. It would be ideal, however, if the same tracer can be used for both qualitative and quantitative purposes. We have labeled some lectins and neoglycoproteins with QD for the purpose of quantitative analyses in glycobiology, and tested its suitability in three different areas in glycobiology: (1) glycosyltransferase, (2) an animal lectin - mannose-binding protein, and (3) the Gal/GalNAc receptor of rat liver membrane. Usefulness of QD-labeled lectins was amply demonstrated by the quantification of galactosyltransferase activity using QD-soybean agglutinin and QD-RCA120 ( Ricinus communis agglutinin). We also showed that QD-labeled neoglycoproteins, QD-Man-BSA and QD-Gal-BSA, can replace radioiodinated counterparts in the binding assays of animal lectins (serum mannose binding protein and hepatic Gal/GalNAc receptor.) The advantage of QD and other europium labels is that it does not decay as radioiodides do. The long shelf-life results in more consistent results from repeated experiments.

Plasma proteins of rainbow trout (Oncorhynchus mykiss) isolated by binding to lipopolysaccharide from Aeromonas salmonicida

In an attempt to find plasma proteins that might be involved in the constitutive resistance of rainbow trout to furunculosis, a disease caused by Aeromonas salmonicida (AS), we purified serum and plasma proteins based on their calcium- and carbohydrate-dependent affinity for A. salmonicida lipopolysaccharide (LPS) coupled to an epoxy-activated synthetic matrix (Toyopearl AF Epoxy 650M). A multimeric family of high molecular weight (96 to 200-kDa) LPS-binding proteins exhibiting both calcium and mannose dependent binding was isolated. Upon reduction the multimers collapsed to subunits of approximately 16-kDa as estimated by 1D-PAGE and exhibited pI values of 5.30 and 5.75 as estimated from 2D-PAGE. Their N-terminal sequences were related to rainbow trout ladderlectin (RT-LL), a Sepharose-binding protein. Polyclonal antibodies to the LPS-purified 16-kDa subunits recognized both the reduced 16-kDa subunits and the non-reduced multimeric forms. A calcium- and N-acetylglucosamine (GlcNAc)-dependent LPS-binding multimeric protein (approximately 207-kDa) composed of 34.5-kDa subunits was purified and found to be identical to trout serum amyloid P (SAP) by N-terminal sequence (DLQDLSGKVFV). A protein of 24-kDa, in reduced and non-reduced conditions, was isolated and had N-terminal sequence identity with a known C-reactive protein (CRP) homologue, C-polysaccharide-binding protein 2 (TCBP2) of rainbow trout. A novel calcium-dependent LPS-binding protein was purified and termed rainbow trout lectin 37 (RT-L37). This protein, composed of dimers, tetramers and pentamers of 37 kDa subunits (pI 5.50-6.10) with N-terminal sequence (IQE(D/N)GHAEAPGATTVLNEILR) showed no close homology to proteins known or predicted from cDNA sequences. These findings demonstrate that rainbow trout have several blood proteins with lectin properties for the LPS of A. salmonicida; the biological functions of these proteins in resistance to furunculosis are still unknown.

The C-type lectin superfamily in the immune system

Protein-carbohydrate interactions serve multiple functions in the immune system. Many animal lectins (sugar-binding proteins) mediate both pathogen recognition and cell-cell interactions using structurally related Ca(2+)-dependent carbohydrate-recognition domains (C-type CRDs). Pathogen recognition by soluble collections such as serum mannose-binding protein and pulmonary surfactant proteins, and also the macrophage cell-surface mannose receptor, is effected by binding of terminal monosaccharide residues characteristic of bacterial and fungal cell surfaces. The broad selectivity of the monosaccharide-binding site and the geometrical arrangement of multiple CRDs in the intact lectins explains the ability of the proteins to mediate discrimination between self and non-self. In contrast, the much narrower binding specificity of selectin cell adhesion molecules results from an extended binding site within a single CRD. Other proteins, particularly receptors on the surface of natural killer cells, contain C-type lectin-like domains (CTLDs) that are evolutionarily divergent from the C-type lectins and which would be predicted to function through different mechanisms.

Effect of shape, size, and valency of multivalent mannosides on their binding properties to phytohemagglutinins

Clusters of di-, tri-, and tetra-antennary alpha-D-mannopyranosides were synthesized in good yields based on the coupling of amine-bearing mono- or trisaccharide [Man alpha(1 --> 6)[Man alpha(1 --> 3)]Man] haptens to poly-isocyanate or -isothiocyanate tethering cores. The relative binding properties of the resulting multivalent ligands were determined by turbidimetric and solid phase enzyme-linked lectin assays (ELLA) using plant lectins (phytohemagglutinins) Concanavalin A (Con A) and Pisum sativum (pea lectin) having four and two carbohydrate binding sites, respectively. Rapid and efficient cross-linking between tetravalent Con A and mannopyranosylated clusters were measured by a microtiter plate version of turbidimetric analyses. In inhibition of binding of the lectins to yeast mannan, the best tetravalent monosaccharide (30) and trisaccharide (31) inhibitors were shown to be 140 and 1155 times more potent inhibitors than monomeric methyl alpha-D-mannopyranoside against pea lectin and Con A, respectively. Compounds 30 and 31 were thus 35- and 289-fold more potent than the reference monosaccharide based on their hapten contents. As a general observation, the ligands bearing the Man alpha(1 --> 6)[Man alpha(1 --> 3)]Man trimannoside structures were found to be more potent inhibitors for Con A than the ligands having single mannoside residues, whereas pea lectin could not discriminate between the two types of ligands.

Enzymatic synthesis of N-linked oligosaccharides terminating in multiple sialyl-Lewis(x) and GalNAc-Lewis(x) determinants: clustered glycosides for studying selectin interactions

Galactosyltransferase, sialyltransferase, and fucosyltransferase were used to create a panel of complex oligosaccharides that possess multiple terminal sialyl-Le(x) (NeuAc alpha 2-3Gal[Fuc alpha 1-3] beta 1-4GlcNAc) and GalNAc-Le(x) (GalNAc[Fuc alpha 1-3]beta 1-4GlcNAc). The enzymatic synthesis of tyrosinamide biantennary, triantennary, and tetraantennary N-linked oligosaccharides bearing multiple terminal sialyl-Le(x) was accomplished on the 0.5 mumol scale and the purified products were characterized by electrospray MS and 1H NMR. Likewise, biantennary and triantennary tyrosinamide oligosaccharides bearing multiple terminal GalNAc-Le(x) determinants were synthesized and similarly characterized. The transfer kinetics of human milk alpha 3/4-fucosyltransferase were compared for biantennary oligosaccharide acceptor substrates possessing Gal beta 1-4GlcNAc, GalNAc beta 1-4GlcNAc, and NeuAc alpha 2-3Gal beta 1-4GlcNAc which established NeuAc alpha 2-3Gal beta 1-4GlcNAc as the most efficient acceptor substrate. The resulting complex oligosaccharides were chemically tethered through the tyrosinamide aglycone to the surface of liposomes containing phosphatidylthioethanol, resulting in the generation of glycoliposomes probe which will be useful to study relationships between binding affinity and the micro- and macro-clustering of selectin ligand.