Structure of six 3-deoxy-D-glycero-D-galacto-nonulosonic acid(Kdn)-containing oligosaccharide-alditols released from oviduct secretions of Ambystoma maculatum. Characterization of the sequence fucosyl(alpha 1-2)[fucosyl(alpha 1-3)]fucosyl(alpha 1-4)-3-deoxy-D-glycero-D-galacto-nonulosonic acid

The O-linked acidic oligosaccharides of the jelly coat surrounding the eggs of Ambystoma maculatum were analyzed by NMR spectroscopy. The structures of the major oligosaccharides were established as follows where Kdn represents 3-deoxy-D-glycero-D-galacto-nonulsonic acid and GalNAc-ol is N-acetylgalactosaminitol: [sequence: see text] As shown for five other amphibian species, the structures of these carbohydrate chains appear to be species specific and can afford a basis for molecular taxonomy. These new sequences also reflect the occurrence of specific fucosyltransferase activities that are characteristic of Ambystoma maculatum.

The glycan moiety of human pancreatic lithostathine. Structure characterization and possible pathophysiological implications

Lithostathine, also known as pancreatic stone protein, pancreatic thread protein or regenerating protein, is a glycoprotein which is normally found in the exocrine pancreas, whereas in other tissues it appears either only under pathological conditions, such as Alzheimer's disease (brain), cancer (colon) or during regeneration (endocrine pancreas). In the latter case, it has been shown recently that it acts as a growth factor which stimulates islet regeneration. Little is known about its glycan moiety, which conceivably might be involved in this tissue specificity and pathophysiological characteristics. Therefore we isolated the major oligosaccharide chains of human pancreatic lithostathine and determined their sequences by means of NMR analysis. We obtained eleven different glycoforms and we were able to determine the sequence of seven of them. They all were from the same site of glycosylation (Thr5) and displayed the same core 2 structure: GlcNAc(beta 1-6)[Gal(beta 1-3)]GalNAc alpha-. They ranged in size from 4 to 9 sugar residues. Elongation was found to proceed from a common tetrasaccharidic core: Gal(beta 1-4)GlcNAc(beta 1-6)[Gal(beta 1-3)]GalNAc-ol through N-acetyllactosamine units. The non-reducing ends of some oligosaccharides carry the antigenic determinant H, with presence of external Fuc linked only in (alpha 1-2) to Gal. All the glycans, except one, carry a sialic acid in (alpha 2-3) linkage to Gal, with one disialylated form which displays a supplementary (alpha 2-6) linkage. These findings are consistent with the polymorphism of the protein, shown by means of SDS gel electrophoresis and isoelectric focusing, either in its native form or after enzymic processing. Moreover, sialylation seems to protect to some extent the Arg11-Ile12 bond from in situ hydrolysis, thus preventing the harmful precipitation of the C-terminal polypeptide in the pancreatic ducts.

Beta-1,2-linked oligomannosides from Candida albicans act as signals for tumor necrosis factor alpha production

Different cell wall components from Candida albicans have been shown to stimulate murine macrophages for tumor necrosis factor alpha (TNF-alpha) secretion. All of these molecules contain beta-1,2-oligomannosides. In order to examine their role in TNF-alpha production, acid-labile oligosaccharides, released from C. albicans VW32 cell wall phosphopeptidomannan by mild acid hydrolysis, and previously shown to correspond to homopolymers of beta-1,2-linked mannopyranosyl units, were separated by gel filtration chromatography according to their degree of polymerization. Murine macrophages incubated with purified oligomannosides (M2 to M8) released TNF-alpha to an extent which was dependent on, although not directly correlated with, the length of the mannosyl chain. Slight activity was observed with M4 and M5; M6 and M7 had virtually no effect, whereas M8 was associated with strong TNF-alpha release. This effect of M8 was dose dependent and was not altered by polymyxin B, known to interfere with lipopolysaccharide-induced TNF-alpha production. These results suggest that stimulation of TNF-alpha release by C. albicans glycoconjugates containing beta-1,2-linked oligomannosides may be due, at least in part, to the presence of these components.

First evidence of human meconium glycoasparagines

During a systematic study of carbohydrate material present in human meconium, in addition to the previously described mucins, glycolipids and free oligosaccharides, we have now characterized a significant quantity of free glycoasparagines. These glycoasparagines have been isolated from human meconium by a combination of ion-exchange, concanavalin A (ConA)-affinity and high-performance liquid (HPLC) chromatographies. Their structures have been established by 400 MHz 1H-NMR spectroscopy. These compounds are related to N-acetyllactosaminic type structures and are based on the common core: [formula: see text] These glycoasparagines are probably derived from both protease and partial exoglycosidase hydrolysis of fetal gastrointestinal N-glycosyl proteins. Their structures are discussed in the context of the known catabolic pathways of N-glycans.

Rat mammary-gland transferrin: nucleotide sequence, phylogenetic analysis and glycan structure

The complete cDNA for rat mammary-gland transferrin (Tf) has been sequenced and also the native protein isolated from milk in order to analyse the structure of the main glycan variants present. A lactating-rat mammary-gland cDNA library in lambda gt10 was screened with a partial cDNA copy of rat liver Tf and subsequently rescreened with 5' fragments of the longest clones. This produced a 2275 bp insert coding for an open reading frame of 695 amino acid residues. This includes a 19-amino acid signal sequence and the mature protein containing 676 amino acids and one N-glycosylation site in the C-terminal domain at residue 490. Phylogenetic analysis was carried out using 14 translated Tf nucleotide sequences, and the derived evolutionary tree shows that at least three gene duplication events have occurred during Tf evolution, one of which generated the N- and C-terminal domains and occurred before separation of arthropods and chordates. The two halves of human melanotransferrin are more similar to each other than to any other sequence, which contrasts with the pattern shown by the remaining sequences. Native rat milk Tf is separated into four bands on native PAGE that differ only in their sialic acid content: one biantennary glycan is present containing either no sialic acid residues or up to three. The complete structures of the two major variants were determined by methylation, m.s. and 400 MHz 1H-n.m.r. spectroscopy. They contain either one or two neuraminic acid residues (alpha 2-->6)-linked to galactose in conventional biantennary N-acetyl-lactosamine-type glycans. Most contain fucose (alpha 1-->6)-linked to the terminal non-reducing N-acetylglucosamine.

Use of a water flip-back pulse in the homonuclear NOESY experiment

A simple modification to the WATERGATE water suppression scheme [Piotto, M., Saudek, V. and Sklenář, V. (1992) J. Biomol. NMR, 2, 661-665] is proposed. Radiation damping is used as an active element during the mixing time of a NOESY experiment, in order to obtain a reproducable state of the water magnetization at the end of the mixing time. Through the use of a water flip-back pulse and a gradient-tailored excitation scheme, we obtain both an excellent water suppression and a water magnetization close to equilibrium at the beginning of the acquisition time. We show experimentally that this modification results in a 20% gain in intensity for all signals when using a relaxation delay of 1.5 s, and also that avoiding a semisaturated state for the water magnetization allows the amide protons as well as other proton resonances to relax to equilibrium with their proper relaxation time.

Native like structure and stability of apo AI in a n-propanol/water solution as determined by 13C NMR

To elucidate the molecular details of the conformation of apolipoprotein AI (apo AI), we have developed an approach related to the solubilization of this protein in 30% n-propanol. We have previously reported the promotion of a native-like structure for apo AI solubilized in n-propanol, as depicted by circular dichroism, fluorescence, and limited proteolytic digestion as compared to the lipid associated form of apo AI. In the present study, we labeled the Lys residues of apo AI with 13C by reductive methylation and used 13C NMR to confirm the formation of a native-like structure of apo AI in this environment. Furthermore, by the above criteria (circular dichroism and 13C NMR) and by using urea and temperature as denaturing agents, we show that the denaturation of the native-like structure of apo AI in n-propanol is a biphasic process. These studies show that in 30% n-propanol, apo AI contains two independently folded structural domains, of markedly different stabilities that might correspond to the amino-terminal and the carboxy-terminal halves of the molecule.

Primary structure of 12 neutral oligosaccharide-alditols released from the jelly coats of the anuran Xenopus laevis by reductive beta-elimination

The O-linked oligosaccharides of the jelly coat surrounding the eggs of Xenopus laevis were analysed by 1H-NMR spectroscopy. Among the 12 neutral oligosaccharide-alditols which have been characterized, three of them possess the following unusual structures: [sequence: see text] As previously observed for six other amphibian species, the carbohydrate chains of the jelly coat of Xenopus eggs display a high species specificity which could support a biological role during the fertilization processes.

Structure of three Kdn-containing oligosaccharide-alditols released from oviducal secretions of Ambystoma tigrinum: characterization of the carbohydrate sequence Fuc (alpha 1-5) [Fuc (alpha 1-4)] Kdn (alpha 2-3/6)

Oligosaccharide-alditols released by reductive beta-elimination from the egg jelly coat of Ambystoma tigrinum were analyzed by 1H NMR spectroscopy. As observed for five other amphibian species, these carbohydrate chains are highly species-specific, and should support the species-specificity of gamete interaction. The carbohydrate chains of Ambystoma tigrinum are characterized by the presence of a new type of sequence: Fuc (alpha 1-5) [(Fuc (alpha 1-4)] Kdn (alpha 2-3/6).

Chemical and immunological characterization of the extracellular galactomannan of Aspergillus fumigatus

The galactomannan (GM) produced extracellularly by Aspergillus fumigatus has been purified by a double sequential hydrazine-nitrous acid treatment of the ethanol precipitate of the culture filtrate. Nuclear magnetic resonance and gas-liquid chromatography-mass spectrometry analysis have been performed on intact GM, acid-hydrolyzed GM, and oligomers resulting from the acetolysis of the acid-hydrolyzed GM. Results show that A. fumigatus GM is composed of a linear mannan core with an alpha-(1-2)-linked mannotetraose repeating unit attached via alpha-(1-6) linkage. Side chains composed of an average of 4 to 5 beta-(1-5)-galactofuranose units are linked to C-6 and C-3 positions of alpha-(1-2)-linked mannose units of the mannan. The immunoreactivity of GM and HCl-hydrolyzed GM was studied by use of human sera from aspergillosis patients and an antigalactofuran monoclonal antibody. The alpha-(1-2) (1-6)-mannan core is not antigenic. The immunogenic galactofuran is found amongst several exocellular glycoproteins. According to a direct enzyme-linked immunosorbent assay with GM as the detector antigen, only 26% of the serum samples from aspergilloma patients (all positive by immunodiffusion assays) give optical density values superior to a cutoff estimated as the mean +/- 3 standard deviations of values obtained with control sera.

Toward an understanding of the biogenesis of the starch granule. Determination of granule-bound and soluble starch synthase functions in amylopectin synthesis

Plant starch synthesis can be distinguished from those of bacterial, fungal, and animal glycogen by the presence of multiple elongation (starch synthases) and branching enzymes. This complexity has precluded genetic assignment of functions to the various soluble starch synthases in the building of amylopectin. In Chlamydomonas, we have recently shown that defects in the major soluble starch synthase lead to a specific decrease in the amount of a subset of amylopectin chains whose length ranges between 8 and 40 glucose residues (Fontaine, T., D'Hulst, C., Maddelein, M.-L., Routier, F., Marianne-Pepin, T., Decq, A., Wieruszeski, J. M., Delrue, B., Van Den Koornhuyse, N., Bossu, J.-P., Fournet, B., and Ball, S. G. (1993) J. Biol. Chem. 268, 16223-16230). We now demonstrate that granule-bound starch synthase, the enzyme that was thought to be solely responsible for amylose synthesis, is involved in amylopectin synthesis. Disruption of the Chlamydomonas granule-bound starch synthase structural gene establishes that synthesis of long chains by this enzyme can become an absolute requirement for amylopectin synthesis in particular mutant backgrounds. In the sole presence of soluble starch synthase I, Chlamydomonas directs the synthesis of a major water-soluble polysaccharide fraction and minute amounts of a new type of highly branched granular material, whose structure is intermediate between those of glycogen and amylopectin. These results lead us to propose that the nature of the elongation enzyme conditions the synthesis of distinct size classes of glucans in all starch fractions.

Change in glycosylation of chicken transferrin glycans biosynthesized during embryogenesis and primary culture of embryo hepatocytes

Transferrins were isolated by immunoaffinity chromatography from chicken serum, chicken embryo serum and from the culture medium of chicken embryo hepatocytes in primary culture. The glycovariants of these three transferrins were separated by ion-exchange chromatography using a fast protein liquid chromatography (FPLC) system. The structures of the oligosaccharide-alditols released by hydrazinolysis from the glycovariants were compared after analysis by a combination of methanolysis, methylation analysis and 1H-NMR spectroscopy. In the three transferrins analysed, the oligosaccharides were of the biantennary N-acetyllactosaminic type, having several prominent features. In particular, the embryo serum transferrin glycan differed from that of chicken serum transferrin by the presence of a bisecting N-acetylglucosamine, suggesting a developmental change in glycosylation. The glycan structure of the transferrin secreted by the embryo hepatocytes in primary culture was marked by the presence of fucose (alpha 1-6) linked to the core N-acetylglucosamine, suggesting that expression of the fucosyltransferase activity is dependent on cell culture conditions. Moreover, comparative analysis of chicken serum transferrin and ovotransferrin glycans reinforces the idea that the glycosylation of two identical polypeptide chains is organ specific.

Structure of the major neutral oligosaccharide-alditols released from the egg jelly coats of Axolotl maculatum. Characterization of the carbohydrate sequence GalNAc(beta 1-4)[Fuc(alpha 1-3)] GlcNAc(beta 1-3/6)

Several O-linked oligosaccharides of the jelly coat surrounding the eggs of Axolotl maculatum were analysed by 1H-NMR spectroscopy. The four major oligosaccharidealditols released by reductive beta-elimination display either the Lewisx (Lex) determinant or the sequence GalNAc(beta 1-4)[Fuc(alpha 1-3)]GlcNAc. This last structure has previously been characterized in allergenically active oligosaccharides isolated from the sea squirt H-antigen, and in the N-linked glycans of Schistosoma mansoni and human urokinase. It represents the major carbohydrate chain found in A. maculatum, the oviduct of which constitutes an excellent source of beta 1-4-acetylgalactosaminyl transferase activity. Moreover, the carbohydrate chains isolated from A. maculatum are quite different from those found in seven other amphibian species, in which the presence of species-specific material has been characterized. The role of carbohydrates appears more and more apparent during the fertilization process, and the diversity of the O-linked oligosaccharides supports such a biological role.

Sialylation and sulfation of the carbohydrate chains in respiratory mucins from a patient with cystic fibrosis

Mucin glycopeptides were prepared from the sputum of a patient suffering from cystic fibrosis. The carbohydrate chains were released by alkaline borohydride treatment. Sialylated and sulfated oligosaccharide-alditols were purified by ion-exchange chromatography, gel filtration, and high performance anion-exchange chromatography. The structures of the oligosaccharide-alditols were determined by high resolution 1H NMR spectroscopy in combination with fast atom bombardment-mass spectrometry. Twenty-four oligosaccharides were characterized and illustrate the diversity of the carbohydrate chains of cystic fibrosis respiratory mucins. Among these 24 oligosaccharide-alditols, 15 are novel structures. Sialylation may occur on the C-6 of the N-acetylgalactosamine involved in the carbohydrate-peptide linkage or on a terminal galactose residue, either on C-3 or on C-6. Sulfation may occur either on the C-3 of a terminal galactose residue or on the C-6 of a N-acetylglucosamine residue. The most complex structures contain sulfated derivatives of the H,X, or Y determinants or a sialylated and sulfated derivative of the X determinant (Structure A).

Soluble forms of alpha-D-mannosidases from rat liver. Separation and characterization of two enzymic forms with different substrate specificities

We have previously reported the substrate specificity of the rat liver cytosolic alpha-D-mannosidase [Haeuw, J. F., Strecker, G., Wieruszeski, J. M., Montreuil, J. & Michalski, J.-C. (1991) Eur. J. Biochem. 202, 1257-1268]. Here, we report the characterization and the purification of this alpha-D-mannosidase and the presence of two soluble forms of alpha-D-mannosidases from rat liver. The cytosolic alpha-D-mannosidase was purified nearly 660-fold with 2.66% recovery to a state approaching homogeneity using: (a) (NH4)2SO4 precipitation; (b) concanavalin-A-Sepharose chromatography; (c) affinity chromatography on a cobalt-chelating Sepharose column; (d) ion-exchange (DEAE-trisacryl M) column chromatography; (e) molecular-size chromatography (Sephacryl S 200). The enzyme was eluted from the final column at an apparent molecular mass of 113 kDa. SDS/PAGE analysis yielded a major protein band at 108 kDa. Moreover, the purification allowed to distinguish two mannosidase activities with different kinetic properties. The first cytosolic activity retained on the cobalt-chelating column was optimally active at neutral pH, was activated by Co2+, was strongly inhibited by swainsonine (Ki = 3.7 microM) but not by deoxymannojirimycin and was active with p-nitrophenyl alpha-D-mannoside (Km = 0.072 mM). Man9GlcNAc was hydrolysed by the purified enzyme down to a Man5GlcNAc structure, i.e. Man(alpha 1-2)Man(alpha 1-2)Man(alpha 1-3)[Man(alpha 1-6)]Man(beta 1-4) GlcNA c, which represents the Man5 oligosaccharide chain of the dolichol pathway formed in the cytosolic compartment during the biosynthesis of N-glycosylprotein glycans. The second activity not retained on the cobalt-chelating column was optimally active at neutral pH, was inhibited by swainsonine (Ki = 28.4 microM) but not by deoxymannojirimycin and was active with p-nitrophenyl alpha-D-mannoside (Km = 0.633 mM). Man9GlcNAc was broken by this enzymic activity down to Man8GlcNAc and Man7GlcNAc structures. Similitaries with endoplasmic reticulum alpha-D-mannosidase exist and this enzyme could be the cytosolic form of the endoplasmic reticulum alpha-D-mannosidase.

Bi-antennary oligo-(N-acetyllactosamino)glycans of I-type are galactosylated preferentially at the GlcNAc beta 1-6Gal linked arms by alpha 1,3-galactosyltransferase of bovine thymus

alpha 1,3-Galactosylation of radiolabelled bi-antennary acceptors Gal beta 1-4GlcNAc beta 1-3(Gal beta 1-4GlcNAc beta 1-6)Gal-R (R = 1-OH, beta 1-4GlcNAc or beta 1-4Glc) with bovine thymus alpha 1,3-galactosyltransferase was studied. At all stages of the reactions the three acceptors reacted faster at the 1-->6 linked arm than at the 1-->3 linked branch. Hence, in addition to the doubly alpha 1,3-galactosylated products, practically pure Gal beta 1-4GlcNAc beta 1-3(Gal alpha 1-3Gal beta 1-4GlcNAc beta 1-6)Gal-R could be obtained from the three acceptors in reactions that had proceeded to near completion. The isomeric mono-alpha 1,3-galactosylated products were identified by using exoglycosidases to remove the branches unprotected by alpha 1,3-galactoses and by subsequently identifying the resulting linear glycans chromatographically.

Toward an understanding of the biogenesis of the starch granule. Evidence that Chlamydomonas soluble starch synthase II controls the synthesis of intermediate size glucans of amylopectin

Low starch mutants of Chlamydomonas reinhardtii were isolated after x-ray mutagenesis of wild-type strain 137C. The mutants accumulated 20-40% of the normal amount and displayed a 2-fold decrease of the total glycogen-primed soluble starch synthase activity. Three different mutant alleles of the st-3 gene were isolated that were characterized by similar defects and displayed a net increase in amylose content. Amylose-primed synthesis of glucan in native gels revealed a complete wipe out of one of the soluble starch synthases. Zymograms and kinetic analyses performed both in the mutant and in partially purified wild type extracts reveal at least two distinct activities that are partly analogous to higher plant soluble starch synthases I and II (SSI and II). The st-3 mutants were defective for SSII. Methylation and debranching of the purified amylopectin fraction clearly show a decrease in the number of intermediate size glucans (dp8 to 50) and an absolute and relative increase of very short glucans (dp2 to 7). These results suggest that a soluble starch synthase may be necessary for the synthesis or maintenance of intermediate size glucans that are the main component of the branched clusters of amylopectin.

Primary structure of human milk octa-, dodeca- and tridecasaccharides determined by a combination of 1H-NMR spectroscopy and fast-atom-bombardment mass spectrometry. Evidence for a new core structure, the para-lacto-N-octaose

Two octasaccharides, two dodecasaccharides and a tridecasaccharide have been isolated from human milk by a combination of paper chromatography, high-performance liquid chromatography and high-performance anion-exchange chromatography. Their structural analysis investigated by 400-MHz 1H- and 13C-NMR spectroscopy and by mass spectrometry led to the following structures. [formula: see text] The two octasaccharides have been previously characterized in human milk; the complete assignment of the 1H and 13C spectra is reported here. One of the dodecasaccharides is a tetrafucosyl derivative with a new core: typeI-(beta 1-3)-typeII-(beta 1-3)-typeII-(beta 1-3)-Gal((beta 1-4)Glc, where typeI = Gal(beta 1-3)GlcNAc and typeII = Gal(beta 1-4)GlcNAc. These oligosaccharides display simultaneously Lewis(b) and Lewis(x) determinants or Lewis(a), Lewis(b) and Lewis(x) determinants.

Isolation and characterisation of hemicelluloses from sunflower hulls

The hemicelluloses extracted from sunflower hulls by repeated alternating oxidative and alkaline treatments were purified by precipitation with Cetavlon and then ion-exchange chromatography on DEAE-trisacryl. The resulting fractions were examined by hydrolysis, methylation, GLC-MS, and NMR spectroscopy. The hemicelluloses are of the glucuronoxylan type with the following structure -->4)-beta-D-Xylp-(1-->4)-[4-O-Me-alpha-D-GlcpA-(1-->2)]-bet a-D-Xylp-(1-->. The polysaccharides differed in the amount of branching; the ratio of the main fraction 4-O-MeGlcA:Xyl was 1:8-9.

Complete 1H- and 13C-resonance assignments for D-mannooligosaccharides of the beta-D-(1-->2)-linked series released from the phosphopeptidomannan of Candida albicans VW.32 (serotype A)

D-Mannooligosaccharides (dp 1 to > 17) were released by mild acid hydrolysis from the phosphopeptidomannan of a Candida albicans strain of A serotype (VW.32). Among these, mannooligosaccharides ranging from bi- to hepta-ose, which were obtained in appreciable amounts, were structurally investigated and found to belong to the beta-D-(1-->2)-linked series. The occurrence of such compounds has already been reported in other Candida albicans strains. The complete 1H- and 13C-resonance assignments for manno-tri- to manno-hepta-ose are reported and general rules applicable for the 1NMR spectrum analysis of linear mannooligosaccharide of the general structure, beta-D-Man p-(1-->2)-[beta-D-Man p-(1-->2)]n-beta-D-Man p are proposed.

Structural analysis of the carbohydrate chains isolated from mistletoe (Viscum album) lectin I

Two glycopeptide fractions prepared from mistletoe (Viscum album) lectin I by Pronase digestion were fractioned by affinity chromatography on a concanavalin A-Sepharose column. With 400-MHz 1H NMR spectroscopy, in conjunction with sugar analysis, the following oligosaccharide structures could be determined: two oligomannose-type glycans in the ratio 4:1, one containing six mannose and the other containing five mannose units, both with two 2-acetamido-2-deoxyglucose units. In addition, a mannotriosyl-->N,N'-diacetylchitobiose glycan containing a xylosyl group and an alpha-fucosyl group (1-->3)-linked to the 2-acetamido-2-deoxyglycosyl-1 residue, a common core element of many plant glycoproteins, was also observed.

Heterogeneity of bovine lactotransferrin glycans. Characterization of alpha-D-Galp-(1-->3)-beta-D-Gal- and alpha-NeuAc-(2-->6)-beta-D-GalpNAc-(1-->4)- beta-D-GlcNAc-substituted N-linked glycans

Lactotransferrin isolated from a pool of mature bovine milk has been shown to contain N-glycosidically-linked glycans possessing N-acetylneuraminic acid, galactose, mannose, fucose, N-acetylglucosamine, and N-acetylgalactosamine. The glycopeptides obtained by Pronase digestion were fractionated by concanavalin A-Sepharose affinity chromatography into three fractions: slightly retained (A), retained (B), and strongly retained (C). The structure of the glycans of the three fractions has been determined by application of methanolysis, methylation analysis, fast atom bombardment-mass spectrometry, and 1H NMR spectroscopy. Diantennary structures without GalNAc were present as partially sialylated and partially (1-->6)-alpha-L-fucosylated structures in Fractions A and B. Sequences containing alpha-D-Galp-(1-->3)-beta-D-Gal on the alpha-D-Man-(1-->6) antenna, and beta-D-GalpNAc-(1-->4)-beta-D-GlcNAc and alpha-NeuAc-(2-->6)-beta-D-GalpNAc-(1-->4)-beta-D-GlcNAc on the alpha-D-Man-(1-->3) antenna were characterized in the oligosaccharide-alditols obtained by reductive cleavage of Fraction B. A series of Man4-9-GlcNAc structures were identified in Fraction C after endo-N-acetyl-beta-D-glucosaminidase digestion. These results show that the structures of bovine lactotransferrin glycans are more heterogeneous than those of previously characterized transferrin glycans.

1H-and 13C-n.m.r. spectroscopy of 2-oxo-3-deoxy-D-glycero-D- galactononulosonic acid-containing oligosaccharide-alditols bearing Lewis X, Lewis Y and A-Lewis Y determinants isolated from the jelly coat of Pleurodeles waltl eggs

Three acidic oligosaccharide-alditols carrying Lewis X, Lewis Y and A-Lewis Y determinants were isolated from the jelly coat of Pleurodeles waltl eggs. These compounds possess the following structures. Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-3[2-oxo-3-deoxy-D- glycero-D-galactononulosonic acid (KDN)alpha 2-6] GalNAc-ol; Fuc alpha 1-2Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-3(KDN alpha 2-6) GalNAc-ol and Fuc alpha 1-2(GalNAc alpha 1-3)Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-3(KDN alpha 2-6)GalNAc-ol. The complete 1H-n.m.r.-spectrum assignment for the three compounds and the 13C-n.m.r. analysis of the A-Lewis Y determinant-containing heptasaccharide are reported.

Oligosaccharide structures of mucins secreted by the human colonic cancer cell line CL.16E

Cl.16E, a stably differentiated clonal derivative of the human colonic cancer cell line HT29, was used to investigate the structure of oligosaccharide chains of mucins in colonic cancer. Secretory mucins were purified by equilibrium density gradient centrifugation in CsCl. Oligosaccharide side chains were isolated after beta-elimination. Compositional analysis of oligosaccharide-alditols performed after purification by gel filtration on a Bio-gel P-6 column showed 1) that GalNAc residues were located exclusively at the reducing ends of the chains, and 2) that fucose was absent from the preparation. Oligosaccharide-alditols were separated by high performance liquid chromatography (HPLC) on quaternary amine packings into a minor neutral fraction representing about 6.5% by weight of released oligosaccharides and four acidic fractions. Two acidic fractions, namely FI and FII encompassing mono- and disialylated structures, respectively, and containing 78% of total oligosaccharide alditols, were separated by HPLC. Structural determinations were carried out using methylation analysis, 1H NMR spectroscopy, and fast atom bombardment-mass spectrometry. Twelve oligosaccharide structures were determined which ranged in size from 3 to 8 residues. These oligosaccharides were based on core types 1, 2, and 4. Elongation of oligosaccharide chains was terminated by addition of sialic acid in alpha 2-3 linkage to Gal beta 1-3R and to Gal beta 1-4R residues. The predominant structure was a hexasaccharide (fraction FII-4). This contrasts with normal colonic mucins whose oligosaccharides were previously found to be based on core 3 structures and carry sialic acids in alpha (2-6) linkage to Gal beta 1-3R, to Gal beta 1-4R, and to GalNAc alpha-R (Podolsky, D.K. (1985) J. Biol. Chem. 260, 8262-8271; Podolsky, D.K. (1985) J. Biol. Chem. 260, 15510-15515). Collectively our findings suggest that Cl.16E colon cancer cells are able to synthesize mucin oligosaccharides of gastric type whose elongation is truncated by premature sialylation.