Synthesis of beta-D-Galf-(1-3)-D-GlcNAc by the trichloroacetamidate method and of beta-D-Galf-(1-6)-D-GlcNAc by SnCl4-promoted glycosylation

Regioselectivity of glycosylation reactions of galactose acceptors: an experimental and theoretical study

Regioselective glycosylations allow planning simpler strategies for the synthesis of oligosaccharides, and thus reducing the need of using protecting groups. With the idea of gaining further understanding of such regioselectivity, we analyzed the relative reactivity of the OH-3 and OH-4 groups of 2,6-diprotected methyl α- and β-galactopyranoside derivatives in glycosylation reactions. The glycosyl acceptors were efficiently prepared by simple methodologies, and glycosyl donors with different reactivities were assessed. High regioselectivities were achieved in favor of the 1→3 products due to the equatorial orientation of the OH-3 group. A molecular modeling approach endorsed this general trend of favoring O-3 substitution, although it showed some failures to explain subtler factors governing the difference in regioselectivity between some of the acceptors. However, the Galp-(β1→3)-Galp linkage could be regioselectively installed by using some of the acceptors assayed herein.

Trypanosoma cruzi surface mucins are involved in the attachment to the Triatoma infestans rectal ampoule

Background

Trypanosoma cruzi, the agent of Chagas disease, is a protozoan parasite transmitted to humans by blood-sucking triatomine vectors. However, and despite its utmost biological and epidemiological relevance, T. cruzi development inside the digestive tract of the insect remains a poorly understood process.

Methods/Principle findings

Here we showed that Gp35/50 kDa mucins, the major surface glycoproteins from T. cruzi insect-dwelling forms, are involved in parasite attachment to the internal cuticle of the triatomine rectal ampoule, a critical step leading to its differentiation into mammal-infective forms. Experimental evidence supporting this conclusion could be summarized as follows: i) native and recombinant Gp35/50 kDa mucins directly interacted with hindgut tissues from Triatoma infestans, as assessed by indirect immunofluorescence assays; ii) transgenic epimastigotes over-expressing Gp35/50 kDa mucins on their surface coat exhibited improved attachment rates (~2–3 fold) to such tissues as compared to appropriate transgenic controls and/or wild-type counterparts; and iii) certain chemically synthesized compounds derived from Gp35/50 kDa mucins were able to specifically interfere with epimastigote attachment to the inner lining of T. infestans rectal ampoules in ex vivo binding assays, most likely by competing with or directly blocking insect receptor(s). A solvent-exposed peptide (smugS peptide) from the Gp35/50 kDa mucins protein scaffolds and a branched, Galf-containing trisaccharide (Galfβ1–4[Galpβ1–6]GlcNAcα) from their O-linked glycans were identified as main adhesion determinants for these molecules. Interestingly, exogenous addition of a synthetic Galfβ1–4[Galpβ1–6]GlcNAcα derivative or of oligosaccharides containing this structure impaired the attachment of Dm28c but not of CL Brener epimastigotes to triatomine hindgut tissues; which correlates with the presence of Galf residues on the Gp35/50 kDa mucins’ O-glycans on the former but not the latter parasite clone.

Conclusion/Significance

These results provide novel insights into the mechanisms underlying T. cruzi-triatomine interplay, and indicate that inter-strain variations in the O-glycosylation of Gp35/50 kDa mucins may lead to differences in parasite differentiation and hence, in parasite transmissibility to the mammalian host. Most importantly, our findings point to Gp35/50 kDa mucins and/or the Galf biosynthetic pathway, which is absent in mammals and insects, as appealing targets for the development of T. cruzi transmission-blocking strategies.

Chagas disease, caused by the protozoan Trypanosoma cruzi, is a life-long and debilitating neglected illness of major significance to Latin America public health, for which no vaccine or adequate drugs are yet available. In this scenario, identification of novel drug targets and/or strategies aimed at controlling parasite transmission are urgently needed. By using ex vivo binding assays together with different biochemical and genetic approaches, we herein show that Gp35/50 kDa mucins, the major T. cruzi epimastigote surface glycoproteins, specifically adhere to the internal cuticle of the rectal ampoule of the triatomine vector, a critical step leading to their differentiation into mammal-infective metacyclic forms. Ex vivo binding assays in the presence of chemically synthesized analogs allowed the identification of a solvent-exposed peptide and a branched, galactofuranose (Galf)-containing trisaccharide (Galfβ1–4[Galpβ1–6]GlcNAcα) as major Gp35/50 kDa mucins adhesion determinants. Overall, these results provide novel insights into the mechanisms underlying the complex T. cruzi-triatomine interplay. In addition, and since the presence of Galf-based glycotopes on the O-glycans of Gp35/50 kDa mucins is restricted to certain parasite strains/clones, they also indicate that the Galfβ1–4[Galpβ1–6]GlcNAcα motif may contribute to the well-established phenotypic variability among T. cruzi isolates. Most importantly, and taking into account that Galf residues are not found in mammals, we propose Gp35/50 kDa mucins and/or Galf biosynthesis as appealing and novel targets for the development of T. cruzi transmission-blocking strategies.

Synthesis of oligosaccharides related to galactomannans from Aspergillus fumigatus and their NMR spectral data

The synthesis of model oligosaccharides related to antigenic galactomannans of the dangerous fungal pathogen Aspergillus fumigatus has been performed employing pyranoside-into-furanoside (PIF) rearrangement and controlled O(5) → O(6) benzoyl migration as key synthetic methods. The prepared compounds along with some previously synthesized oligosaccharides were studied by NMR spectroscopy with the full assignment of ¹H and ¹³C signals and the determination of ¹³C NMR glycosylation effects. The obtained NMR database on ¹³C NMR chemical shifts for oligosaccharides representing galactomannan fragments forms the basis for further structural analysis of galactomannan related polysaccharides by a non-destructive approach based on the calculation of the ¹³C NMR spectra of polysaccharides by additive schemes.

Galactofuranose antigens, a target for diagnosis of fungal infections in humans

The use of biomarkers for the detection of fungal infections is of interest to complement histopathological and culture methods. Since the production of antibodies in immunocompromised patients is scarce, detection of a specific antigen could be effective for early diagnosis. D-Galactofuranose (Galf) is the antigenic epitope in glycoconjugates of several pathogenic fungi. Since Galf is not biosynthesized by mammals, it is an attractive candidate for diagnosis of infection. A monoclonal antibody that recognizes Galf is commercialized for detection of aspergillosis. The linkage of Galf in the natural glycans and the chemical structures of the synthesized Galf-containing oligosaccharides are described in this paper. The oligosaccharides could be used for the synthesis of artificial carbohydrate-based antigens, not enough exploited for diagnosis.

D-Galactofuranose (Galf) is the unit in polysaccharides and glycoconjugates of several pathogenic fungi that is recognized by the immune system. Since Galf is not synthesized by mammals, it is an attractive candidate for diagnosis of infection. Since the production of antibodies in immunocompromised patients is scarce, detection of a specific antigen could be effective for early diagnosis. An antibody that recognizes Galf is commercialized for the detection of aspergillosis. Chemically synthesized Galf-containing oligosaccharides, reviewed in this paper, could therefore be used for the synthesis of artificial carbohydrate-based antigens and in diagnosis.

Convergent synthesis of isomeric heterosaccharides related to the fragments of galactomannan from Aspergillus fumigatus

Aspergillus fumigatus is a very common fungus with high pathogenic potential for immunosuppressed hospital patients. A. fumigatus galactomannan, being the part of its cell wall, is considered as a promising candidate for vaccine and diagnostic test-systems. In this article we report the convergent synthesis of pentasaccharide fragments of the galactomannan containing the β-(1→5)-linked galactofuranoside chain attached to O-3 or O-6 of a spacer-armed mannopyranoside residue. The synthesis of selectively protected galactofuranoside precursors has been performed using recently developed pyranoside-into-furanoside (PIF) rearrangement. For assembling the target galactomannan structures the [1 + 2 + 2]-scheme was applied. This strategy was shown to be highly efficient and can easily be extended to the synthesis of longer fragments of thegalactomannan.

Synthesis of galactofuranosyl-(1 → 5)-thiodisaccharide glycomimetics as inhibitors of a β-d-galactofuranosidase

Description of the synthesis, molecular modeling and inhibitory properties of furanosyl thiodisaccharides that are mimetics of the motif β-d-Galf-(1 → 5)-d-Galf, found in glycoconjugates of pathogenic microorganisms.

Synthesis of the O-linked hexasaccharide containing β-D-Galf-(1→2)-β-D-Galf in Trypanosoma cruzi mucins

The hexasaccharide β-D-Galp-(1→2)-[β-D-Galp-(1→3)]-β-D-Galp-(1→6)-[β-D-Galf(1→2)-β-D-Galf(1→4)]-D-GlcNAc (1) is the largest carbohydrate structure released as alditol by reductive β-elimination from mucins of some strains of T. cruzi. The terminal β-D-Galp units are sites of sialylation by trans-sialidase which transfers sialic acid from the host to the parasite. Hexasaccharide 1 was synthesized by a [3 + 3]-convergent strategy based on a nitrile assisted glycosylation, using the trichloroacetimidate method. The β-D-Galf-(1→2)-β-D-Galf-D-GlcNAc synthon was sequentially constructed from the reducing end to the non-reducing end employing benzyl α-D-galactofuranoside as starting material for the internal Galf unit. The choice of this novel precursor, obtained in one-reaction step from galactose, allowed the introduction of an orthogonal and participating levulinoyl group at O-2. Thus, the diastereoselective construction of the Galf-β(1→4)-GlcNAc linkage by the trichloroacetimidate method of glycosylation was achieved. The (1)H NMR spectrum of alditol 2 was identical to the product released by β-elimination from the parasite mucin.

Glycosylation studies on conformationally restricted 3,5-O-(di-tert-butylsilylene)-D-galactofuranosyl trichloroacetimidate donors for 1,2-cis α-D-galactofuranosylation

Conformationally restricted 3,5-O-di-tert-butylsilylene-D-galactofuranosyl trichloroacetimidate donors were synthesized from allyl α-D-galactofuranoside for the construction of 1,2-cis α-D-galactofuranosyl linkages. Glycosylation reactions were performed with several acceptors, including D-galactono-1,4-lactone, D-rhamnopyranosyl, and D-mannopyranosyl derivatives. The influence of the temperature and the reaction solvents was evaluated, as well as the 6-O-substitution pattern of the donor. The higher α-selectivities were obtained at -78 °C in diethyl ether as solvent. 6-O-Acetyl substitution on constrained donor increased the α-selectivity compared to the 6-O-benzyl substitution. Almost no selectivities were observed in the non-participating solvent CH(2)Cl(2). In contrast, ethereal solvents enhanced the α-selectivity suggesting a participating effect in the reaction intermediate.

Influence of the solvent in low temperature glycosylations with O-(2,3,5,6-tetra-O-benzyl-β-D-galactofuranosyl) trichloroacetimidate for 1,2-cis α-D-galactofuranosylation

Glycosylation studies for the construction of 1,2-cis α-linkages with O-(2,3,5,6-tetra-O-benzyl-β-D-galactofuranosyl) trichloroacetimidate (1) and several acceptors, including D-mannosyl and l-rhamnosyl derivatives were performed. The reactions were conducted at low temperatures using CH(2)Cl(2), Et(2)O, and acetonitrile as solvents. A non-participating solvent such as CH(2)Cl(2) at -78°C, favored the α-D-configuration. In contrast, acetonitrile strongly favored the β-D-configuration, whereas no selectivities were observed with Et(2)O. The use of thiophene as an additive did not enhance the α-D-selectivity as in the pyranose counterpart. Although selectivities strongly depended on the acceptor, trichloroacetimidate 1 constitutes a valuable donor for the synthesis of α-D-Galf-(1→2)-l-Rha and α-D-Galf-(1→6)-D-Man. As these motifs are present in pathogenic microorganisms, these procedures described here are useful for the straightforward synthesis of natural oligosaccharides.

Total synthesis of the Bacteroides fragilis zwitterionic polysaccharide A1 repeating unit

Nearly all bacteria capsular polysaccharides are T-cell-independent antigens that do not promote immunoglobulin class switching from IgM to IgG nor memory responses. In contrast, zwitterionic polysaccharides activate T-cell-dependent immune responses by major histocompatability complex class II presentation, a mechanism previously believed to be reserved for peptidic antigens. The best studied zwitterionic polysaccharide, polysaccharide A1 (PS A1) is found on the capsule of the commensal bacteria Bacteroides fragilis . Its potent immunomodulatory properties have been linked to postoperative intra-abdominal abscess formation. Here, we report the synthesis of the PS A1 tetrasaccharide repeating unit (2) as a tool to investigate the biological role of this polysaccharide. A modular synthetic strategy originating from the reducing end of the PS A1 repeating unit was unsuccessful and illustrated the limitations of glycosylation reactions between highly armed glycosylating agents and poor nucleophiles. Thus, a [3 + 1] glycosylation relying on trisaccharide 5 and pyruvalated galactose 6 was used to complete the first total synthesis of the PS A1 repeating unit (2).

Synthesis of trisaccharides containing internal galactofuranose O-linked in Trypanosoma cruzi mucins

The trisaccharides beta-D-Galf-(1-->2)-beta-D-Galf-(1-->4)-D-GlcNAc (5) and beta-D-Galp-(1-->2)-beta-D-Galf-(1-->4)-D-GlcNAc (6) constitute novel structures isolated as alditols when released by reductive beta-elimination from mucins of Trypanosoma cruzi (Tulahuen strain). Trisaccharides 5 and 6 were synthesized employing the aldonolactone approach. Thus, a convenient D-galactono-1,4-lactone derivative was used for the introduction of the internal galactofuranose and the trichloroacetimidate method was employed for glycosylation reactions. Due to the lack of anchimeric assistance on O-2 of the galactofuranosyl precursor, glycosylation studies were performed under different conditions. The nature of the solvent strongly determined the stereochemical course of the glycosylation reactions when the galactofuranosyl donor was substituted either by 2-O-Galp or 2-O-Galf.

Chemistry and biology of galactofuranose-containing polysaccharides

The thermodynamically less stable form of galactose-galactofuranose (Galf)-is essential for the viability of several pathogenic species of bacteria and protozoa but absent in this form in mammals, so the biochemical pathways by which Galf-containing glycans are assembled and catabolysed are attractive sites for drug action. This potential has led to increasing interest in the synthesis of molecules containing Galf residues, their subsequent use in studies directed towards understanding the enzymes that process these residues and the identification of potential inhibitors of these pathways. Major achievements of the past several years have included an in-depth understanding of the mechanism of UDP-galactopyranose mutase (UGM), the enzyme that produces UDP-Galf, which is the donor species for galactofuranosyltransferases. A number of methods for the synthesis of galactofuranosides have also been developed, and practitioners in the field now have many options for the initiation of a synthesis of glycoconjugates containing either alpha- or beta-Galf residues. UDP-Galf has also been prepared by a number of approaches, and it appears that a chemoenzymatic approach is currently the most viable method for producing multi-milligram amounts of this important intermediate. Recent advances both in the understanding of the mechanism of UGM and in the synthesis of galactofuranose and its derivatives are highlighted in this review.

Differential O-3/O-4 regioselectivity in the glycosylation of α and β anomers of 6-O-substituted N-dimethylmaleoyl-protected d-glucosamine acceptors

An assessment of the relative O-3/O-4 reactivities of both methyl alpha- and beta-d-glycosides of N-dimethylmaleoyl (DMM) d-glucosamine acceptors protected at O-6 with benzoyl (Bz), benzyl (Bn), and tert-butyldiphenylsilyl (TBDPS) groups is presented using per-O-benzoylated beta-d-galactofuranosyl and per-O-acetylated alpha-d-galactopyranosyl trichloroacetimidates as glycosyl donors. Using the former donor, the alpha anomer of the 6-O-benzoylated compound gave exclusive substitution at O-3, whereas the other two compounds with alpha-configuration kept this site as preferential. The beta anomer of the 6-O-benzoylated compound gave the same amounts of reaction products on O-3 and O-4, whereas the other beta analogs carried a more reactive O-4. The same reactions were carried out using as donor the less-reactive per-O-acetylated alpha-d-galactopyranosyl trichloroacetimidate. Although the same trend was found to occur, the O-4 was always relatively more reactive with the pyranosyl donor than with the furanosyl donor, when keeping the remaining factors constant. Furthermore, the beta anomers of the acceptor gave almost exclusive substitution at O-4. These observations confirm and extend the utility of these 'matching' donor and acceptor reactivities.

Synthesis of α-d-Galf-(1→2)-d-galactitol and α-d-Galf-(1→2)[β-d-Galf-(1→3)]-d-galactitol, oligosaccharide derivatives from Bacteroides cellulosolvens glycoproteins

The synthesis of alpha-D-galactofuranosyl-(1-->2)-D-galactitol, which has been isolated by reductive beta-elimination from glycoproteins of Bacteroides cellulosolvens and Clostridium thermocellum, is described. The approach of selective glycosylation of an aldono-1,4-lactone by the trichloroacetimidate method was employed. The synthesis of alpha-D-Gal f-(1-->2)[beta-D-Gal f-(1-->3)]-D-Galol, that contains Gal f units in both anomeric configurations, is also reported. These are the first synthetic oligosaccharides with alpha-D-Gal f, previously found in natural products.

Facile synthesis of benzyl β-d-galactofuranoside. A convenient intermediate for the synthesis of d-galactofuranose-containing molecules

Benzyl beta-D-galactofuranoside was efficiently obtained from 1,2,3,5,6-penta-O-benzoyl-alpha,beta-D-galactofuranose, via benzyl 2,3,5,6-tetra-O-benzoyl-beta-D-galactofuranoside. Conditions for the O-debenzylation were investigated in order to evaluate the synthetic application of the benzyl group as an anomeric protector of a galactofuranose moiety in synthetic strategies involving galactofuranose.

A comparative study of the influence of some protecting groups on the reactivity of d-glucosamine acceptors with a galactofuranosyl donor

Competitive glycosylation experiments with a galactofuranosyl trichloroacetimidate donor were performed with glucosamine acceptors having a free 4-OH group and carrying different protecting groups at N-2, O-3, and O-6. The most reactive acceptor is the N-dimethylmaleimido 3,6-di-O-benzylated derivative (6c), which reacts even faster than the oxazolidinone 1a. Molecular orbital calculations have helped to rationalize these experimental facts in terms of a hard-hard reaction occurring between the donor and the acceptor.

Facile synthesis of α-D-Araf-(1→5)-D-Galf, the linker unit of the arabinan to the galactan in Mycobacterium tuberculosis

The arabinogalactan is a crucial constituent of the cell wall of mycobacteria. Both monosaccharides (arabinose and galactose) are found in the furanose configuration, absent in mammals. An efficient synthesis of α-D-Araf-(1→5)-D-Galf, the linker unit of the arabinan to the galactan, is described. The strategy relies on the use of a conveniently substituted D-galactono-1,4-lactone as a precursor of the reducing furanose ring. The glycosylation step was performed by the tin(IV) chloride promoted method using 1,2,3,5-tetra-O-benzoyl-α,β-D-arabinofuranose. The arabinose donor was obtained in a crystalline state in one step by benzoylation of arabinose in hot pyridine. Selective glycosylation of the exocyclic OH-5 was obtained in 75% yield to give 2,3,5-tri-O-benzoyl-α-D-arabinofuranosyl-(1→5)-2,6-di-O-pivaloyl-D-galactono-1,4-lactone. Reduction with disiamylborane gave the disaccharide synthon, useful for further glycosylations. Dec-9-enyl α-D-Araf-(1→5)-β-D-Galf, a convenient substrate for arabinofuranosyl transferases studies, was obtained by the trichloroacetimidate method of glycosylation.Key words: arabinofuranose, galactofuranose, Mycobacterium arabinogalactan, trichloroacetimidate, tin(IV) chloride.

Syntheses of beta-d-Galf-(1-->6)-beta-d-Galf-(1-->5)-d-Galf and beta-d-Galf-(1-->5)-beta-d-Galf-(1-->6)-d-Galf, trisaccharide units in the galactan of Mycobacterium tuberculosis

The galactofuran is a crucial constituent of the cell wall of mycobacteria. An efficient synthesis of the two trisaccharide units of the galactan is described. The strategy relies on the use of substituted d-galactono-1,4-lactones as precursors for the internal and the reducing galactofuranoses. Dec-9-enyl beta-d-Galf-(1-->6)-beta-d-Galf-(1-->5)-beta-d-Galf (2) and dec-9-enyl beta-d-Galf-(1-->5)-beta-d-Galf-(1-->6)-beta-d-Galf (9) so far reported as convenient substrates for the galactofuranosyl transferase, and possibly useful for immunological studies, were obtained by the trichloroacetimidate method of glycosylation.

A novel synthesis of D-galactofuranosyl, D-glucofuranosyl and D-mannofuranosyl 1-phosphates based on remote activation of new and free hexofuranosyl donors

The selective synthesis of 1,2-cis-hexofuranosyl 1-phosphates was readily accomplished according to a procedure based on the 'Remote Activation Concept'. This approach required (i) the preparation of suitable 1,2-trans-hexofuranosyl donors, so that new heterocyclic thiofuranosides were designed and synthesized, (ii) the stereocontrolled phosphorylation of the corresponding unprotected donors and (iii) the simple and fast purification of the resulting anomeric phosphates. This approach showed to be equally efficient in the galactose, glucose and mannose series.

Synthesis of alpha-D-Galp-(1-->3)-beta-D-Galf-(1-->3)-D-man, a terminal trisaccharide of Leishmania type-2 glycoinositolphospholipids

The synthesis of alpha-D-Galp-(1-->3)-beta-D-Galf-(1-->3)-D-Man, present in the type-2 glycoinositolphospholipids and in the core of the lipophosphoglycan of Leishmania, is described. The glycosyl aldonolactone approach, followed by reduction of the lactone with diisoamylborane, was utilized for the introduction of the internal galactofuranosyl unit and the trichloroacetimidate method for the O-glycosidation reaction. A high-yield synthesis of the beta-D-Galf-(1-3)-D-Man unit, also present in the lipopeptidophosphoglycan of Trypanosoma cruzi, is reported.

Trypanosoma cruzi surface mucins with exposed variant epitopes

The protozoan parasite Trypanosoma cruzi, the agent of Chagas disease, has a large number of mucin molecules on its surface, whose expression is regulated during the life cycle. These mucins are the main acceptors of sialic acid, a monosaccharide that is required by the parasite to infect and survive in the mammalian host. A large mucin-like gene family named TcMUC containing about 500 members has been identified previously in T. cruzi. TcMUC can be divided into two subfamilies according to the presence or absence of tandem repeats in the central region of the genes. In this work, T. cruzi parasites were transfected with one tagged member of each subfamily. Only the product from the gene with repeats was highly O-glycosylated in vivo. The O-linked oligosaccharides consisted mainly of beta-d-Galp(1-->4)GlcNAc and beta-d-Galp(1-->4)[beta-d-Galp(1-->6)]-d-GlcNAc. The same glycosyl moieties were found in endogenous mucins. The mature product was anchored by glycosylphosphatidylinositol to the plasma membrane and exposed to the medium. Sera from infected mice recognized the recombinant product of one repeats-containing gene thus showing that they are expressed during the infection. TcMUC genes encode a hypervariable region at the N terminus. We now show that the hypervariable region is indeed present in the exposed mature N termini of the mucins because sera from infected hosts recognized peptides having sequences from this region. The results are discussed in comparison with the mucins from the insect stages of the parasite (Di Noia, J. M., D'Orso, I., Sánchez, D. O., and Frasch, A. C. C. (2000) J. Biol. Chem. 275, 10218-10227) which do not have variable regions.

Synthesis of galactofuranosyl-containing oligosaccharides corresponding to the glycosylinositolphospholipid of Trypanosoma cruzi

The oligosaccharide beta-D-Galf-(1-->3)-alpha-D-Manp-(1-->2)-[beta-D-Galf- (1-->3)]-alpha-D-Manp-(1-->2)-alpha-D-Manp corresponds to the terminal end of the glycosylinositolphospholipid oligosaccharide of the protozoan Trypanosoma cruzi, the causative agent of Chagas' disease. Syntheses of methyl or ethylthio glycosides of the terminal disaccharide, trisaccharide, tetrasaccharide, and pentasaccharide corresponding to this structure are described. These syntheses employ the selective activation of a phenyl 1-selenogalactofuranoside or a phenyl 1-selenomannopyranoside donor over ethyl 1-thioglycoside acceptors with NIS-TfOH.

Separation of Galfbeta1-->XGlcNAc and Galpbeta1-->XGlcNAc (X = 3, 4, and 6) as the alditols by high-pH anion-exchange chromatography and thin-layer chromatography: characterization of mucins from Trypanosoma cruzi

The O-linked N-acetylglucosamine oligosaccharides in the mucins of Trypanosoma cruzi may contain galactofuranose or galactopyranose, depending on the strain, one of the components being the disaccharide. Since galactofuranose is a site for antibody recognition, it is desirable to have a sensitive method for the detection of the galactofuranosyl structures. In this paper, we present procedures for the separation of Galfbeta1-->XGlcNAc and Galpbeta1-->XGlcNAc (X = 3, 4, and 6) as the corresponding alditols by high-pH anion-exchange chromatography with pulse amperometric detection. All the isomeric disaccharides could be resolved on a CarboPac PA-10 column, the galactofuranose-containing disaccharides being more retained in the column. GlcNAcol and Galfbeta1-->4(Galpbeta1-->6)GlcNAcol could be analyzed in the same run. The compounds could also be separated by thin-layer chromatography on silica gel 60, a convenient method for analysis of the radiolabeled alditols obtained by reductive beta-elimination in the presence of NaB(3)H(4). Both methods were applied for the analysis of the O-linked sugars in the mucins of T. cruzi CL 14 and revealed that they contained only N-acetylglucosamine and the disaccharide Galpbeta1-->4GlcNAc.