Structures of O-glycosidically linked oligosaccharides isolated from human meconium glycoproteins

The structure of the major O-glycosidically linked neutral and acidic oligosaccharides isolated from human meconium glycoproteins were established. Neutral and acidic oligosaccharides were released by alkaline borohydride treatment, purified by Biogel P-6 and fractionated by high-performance liquid chromatography. This approach resulted in 50 neutral and 30 acidic oligosaccharides. The present study reports the primary structural analysis of five neutral oligosaccharides, ten monosialylated oligosaccharides, one monosialylated monosulfated oligosaccharide and three disialylated oligosaccharides, by permethylation, fast-atom-bombardment mass spectrometry analysis and 400-MHz 1H-NMR spectroscopy. The following structure have not been described previously: (formula; see text) The intestinal glycoproteins of human meconium are characterized as high molecular mass compounds with numerous carbohydrate chains of the mucin type. These mucins are a rich source of carbohydrate structures which express multiple blood group activities and occur as membrane-associated antigens, recognized by hybridoma antibodies [1-4]. A previous study [5] described the structure of fifteen free oligosaccharides derived from catabolism of O- and N-glycans accumulating in new born meconium. In the same group [6] the research has been extended to glycoasparagines with the description of thirteen of them by high resolution 1H-NMR spectroscopy analysis. From O-glycosidically linked glycoproteins, further studies [7] established the structures of nine major monosaccharides to tetrasaccharides obtained after mild acid hydrolysis and base-borohydride degradation from meconium samples of group O secretors. These oligosaccharides were derived from meconium glycopeptides which had been depleted of I- and i-antigen activities. Recently [8], neutral and acidic oligosaccharide-alditols obtained by alkaline borohydride degradation of human meconium glycoproteins have been separated by HPLC on an anion-exchange column. The neutral fraction was further purified by normal-phase and reversed-phase chromatography while acidic fractions were fractionated only by normal-phase chromatography. Thus, we have isolated several low molecular mass oligosaccharides of different size and composition and also isomers which vary in linkage position or anomer configuration. Using methylation analysis, 1H-NMR spectroscopy and fast-atom-bombardment mass spectrometry (FAB-MS), we propose the primary structure for 19 major oligosaccharides.

Complete 1H- and 13C-n.m.r. assignments for two sulphated oligosaccharide alditols of hen ovomucin

The complete 1H- and 13C-n.m.r. assignments for beta-D-Galp-(1----4)-beta-D-GlcpNAc-6-SO3H-(1----6)-[beta-D-Galp-(1----3 )]- D-GalNAcol and alpha-NeuAcp-(2----3)-beta-D-Galp-(1----3)-[beta-D-Galp-(1----4)-b eta-D- GlcpNAc-6-SO3H-(1----6)]-D-GalNAcol were made by a combination of 2-D correlation experiments (Relayed-Cosy; and 13C,1H Correlation-shift n.m.r. spectroscopy), and 1-D n.m.r. spectroscopy. The results illustrate the ability of these methods to locate sulphate and NeuAc groups in anionic mucinous glycoproteins.

Primary structure of human milk nona- and decasaccharides determined by a combination of fast atom bombardment mass spectrometry and 1H-/13C-nuclear magnetic resonance spectroscopy. Evidence for a new core structure, iso-lacto-N-octaose

The structure of a nonasaccharide and of two decasaccharides isolated from human milk has been investigated by using methylation, fast atom bombardment mass spectrometry and 1H-/13C-nuclear magnetic resonance spectroscopy. The structures of these oligosaccharides were: trifucosyllacto-N-hexaose; Fuc alpha 1-2Gal beta 1-3(Fuc alpha 1-4)GlcNAc beta 1-3[Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-6]Gal beta 1-4Glc, difucosyllacto-N-octaoses; Gal beta 1-3(Fuc alpha 1-4)GlcNAc beta 1-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-6[Gal beta 1-3GlcNAc beta 1-3]Gal beta 1-4Glc and Gal beta 1-3GlcNAc beta 1-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-6[Fuc alpha 1-3 Gal beta 1-3GlcNAc beta 1-3]Gal beta 1-4Glc. The two decasaccharides possess a new type of core structure proposed to be named iso-lacto-N-octaose.

Assignment of the 1H- and 13C-NMR spectra of eight oligosaccharides of the lacto-N-tetraose and neotetraose series

The assignment of the 13C- and 1H-NMR spectra of eight oligosaccharides of the lacto-N-tetraose and neotetraose series was obtained from homonuclear and heteronuclear correlation spectroscopy. These analyses were performed on the following compounds: 1. Gal beta 1-3GlcNAc beta 1-3Gal beta 1-4Glc; 2. NeuAc alpha 2-3Gal beta 1-3GlcNAc beta 1-3Gal beta 1-4Glc; 3. Gal beta 1-3[NeuAc alpha 2-6]GlcNAc beta 1-3Gal beta 1-4Glc; 4. NeuAc alpha 2-3Gal beta 1-3[NeuAc alpha 2-6]GlcNAc beta 1-3Gal beta 1-4Glc; 5. NeuAc alpha 2-3Gal beta 1-3[Fuc alpha 1-4]GlcNAc beta 1-3Gal beta 1-4Glc; 6. Fuc alpha 1-2Gal beta 1-3[NeuAc alpha 2-6]GlcNAc beta 1-3Gal beta 1-4Glc; 7. Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc; 8. NeuAc alpha 2-6Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc.

Complete analysis of the 1H- and 13C-NMR spectra of four blood-group A active oligosaccharides

The fully assigned 1H and 13C-NMR spectra of four group A oligosaccharides by use of multiple-relayed, coherence-transfer chemical-shift-correlated spectroscopy (multiple-RELAY-COSY) and 1H-/13C-correlation spectroscopy are reported. These analyses were performed on the following compounds: III-A; GalNAc alpha 1-3[Fuc alpha 1-2]Gal: VI-A; GalNAc alpha 1-3[Fuc alpha 1-2]Gal beta 1-3[Fuc alpha 1-4]GlcNAc beta 1-3Gal: VII-A-1; GalNAc alpha 1-3[Fuc alpha 1-2]Gal beta 1-3[Fuc alpha 1-4]GlcNAc beta 1-3Gal beta 1-1Glycerol: VII-A-2; GalNAc alpha 1-3[Fuc alpha 1-2]Gal beta 1-3[Fuc alpha 1-4]GlcNAc beta 1-3Gal beta 1-4Glc.

Sequential 1H and 13C resonance assignments for an octa- and decasaccharide of the N-acetyllactosamine type by multiple-step relayed correlation and heteronuclear correlation nuclear magnetic resonance

400 MHz 1H-NMR and 100 MHz 13C-NMR spectra of a neutral octasaccharide and of a disialyldecasaccharide of the N-acetyllactosamine type were studied. The resonance assignments were made by combining multiple-relayed coherence-transfer chemical-shift-correlated spectroscopy (multiple-RELAY-COSY) and 1H/13C-shift correlated 2D experiments. The complete analysis of the 1H and 13C spectra was performed.

Microheterogeneity and structures of neutral glycans present in quail ovomucoid

Anionic chromatography of oligosaccharide-alditols obtained by alkaline hydrolysis of quail ovomucoid glycopeptides resulted in the isolation of a major neutral fraction (83%) which was separated into 14 fractions by high-performance liquid chromatography on an alkylamine silica column. The structures of nine oligosaccharide-alditols were determined. By the identification of mannobiosido-, and mannotriosido-di-N-acetylchitobiose mixed with N-acetyl-lactosaminic and oligomannosidic-types oligosaccharides, we demonstrate the high microheterogeneity of the glycans presents in the neutral fraction of this glycoprotein and suggest that ovomucoid glycosylation uses several pathways.

400-MHz 1H-NMR spectroscopy of fucosylated tetrasialyl oligosaccharides isolated from normal and cirrhotic alpha 1-acid glycoprotein

The comparative study of fucosylated tetrasialyl-oligosaccharides isolated from normal and cirrhotic alpha 1-AGP was performed using permethylation and 400-MHz 1H-NMR spectroscopy. These results clearly show the tetraantennary structure of these two oligosaccharides with hyperfucosylation for the tetrasialylated fraction from cirrhotic alpha 1-AGP. In the latter oligosaccharide the simultaneous presence on two antennae (7 and 7') of the sialosyl Lewis X determinant NeuAc-(alpha 2-3) Gal(beta 1-4) [Fuc(alpha 1-3)] GlcNAc has been observed. Moreover the 5 and 5' antennae were alpha 2-6 sialylated but without fucose.

Catabolism of N-glycosylprotein glycans: evidence for a degradation pathway of sialylglyco-asparagines resulting from the combined action of the lysosomal aspartylglucosaminidase and endo-N-acetyl-beta-D-glucosaminidase. A 400-MHz 1H-NMR study

A mixture of sialylglycoasparagines and sialylglycopeptides was successively incubated with lysosomal extracts, at two pH values, first at pH 7.5 and then at pH 4. The 1H-NMR analysis of the sialyloligosaccharides released during the enzymatic digestion demonstrates the sequential action of aspartylglucosaminidase and an endo-N-acetyl-beta-D-glucosaminidase which release sialyloligosaccharides identical to the reference sugars isolated from the urine of patients suffering from sialidosis. This process represents a new catabolic pathway for N-glycosyl-proteins which may account for the appearance of the oligosaccharides stored in tissues and urine of patients suffering from lysosomal diseases.

Primary structure of the glycans from mouse serum and milk transferrins

A 'serotransferrin-like' protein was purified from mouse milk. This serotransferrin cross-reacts immunologically with the serotransferrin isolated from mouse plasma and not with the mouse lactotransferrin (lactoferrin). Sugar analysis of the three transferrins, i.e. serotransferrin, milk 'serotransferrin-like' protein and lactotransferrin, revealed that the major difference between the glycan primary structure of mouse serotransferrin and those of mouse milk 'serotransferrin-like' protein and lactotransferrin concerns essentially the presence of one fucose residue in the last two proteins. For structural determination, the N-glycosidically linked glycans were released from the protein by a reductive cleavage of the oligosaccharide-protein linkage under strong alkaline conditions. The primary structure of the released oligosaccharide alditols was determined by methylation analysis and 400 MHz 1H-n.m.r. spectroscopy. The oligosaccharide alditols released from milk 'serotransferrin-like' protein and lactotransferrin were identical and were identified as disialylated biantennary glycans of the N-acetyl-lactosamine type with a fucose residue alpha-1,6-linked to the N-acetylglucosamine residue conjugated to the peptide chain and having the following primary structure: NeuAc(alpha 2-6)Gal(beta 1-4)GlcNAc(beta 1-2)Man(alpha 1-3)[NeuAc(alpha 2-6)Gal(beta 1-4)GlcNAc(beta 1-2)Man(alpha 1-6)]Man(beta 1-4)GlcNAc(beta 1-4)[Fuc(alpha 1-6)]GlcNAc(beta 1-N)Asn. The serotransferrin glycan has the same primary structure but is only partially fucosylated (10-15%).

Primary structure of an N-glycosidic carbohydrate unit derived from Sophora japonica lectin

The lectin isolated from Sophora japonica seeds is a glycoprotein which binds oligosaccharides with non-reducing terminal Gal beta(1----3/4)GlcNac beta 1----units. The carbohydrate moiety of the lectin is composed of fucose, xylose, mannose and N-acetylglucosamine. The major glycopeptide of the lectin, prepared by pronase digestion, was derivatized with fluorescein isothiocyanate, purified by PAGE and examined by exoglycosidase digestion as well as purified by gel filtration through Bio-Gel P6-DG and investigated by methylation analysis and 400-MHz 1H-NMR spectroscopy. The primary structure of the glycopeptide was established to be as follows. (Formula: see text). Structures similar to this containing a (beta 1-2)xylosyl substituent on the core beta-mannosyl residue and an inner core (alpha 1-3)fucosyl substituent seem to occur frequently in plant glycoproteins.

Structure of the monosialyl oligosaccharides derived from salivary gland mucin glycoproteins of the Chinese swiftlet (genus Collocalia). Characterization of novel types of extended core structure, Gal beta(1----3)[GlcNAc beta(1----6)] GalNAc alpha(1----3)GalNAc(-ol), and of chain termination, [Gal alpha(1----4)]0-1[Gal beta(1----4)]2GlcNAc beta(1----.)

The mucus glycoproteins, the so-called nest-cementing substance, from the salivary gland of Chinese swiftlets (genus Collocalia) are mainly constituted of sialic acid-rich O-glycosylproteins. Alkaline reductive treatment of the crude material led to the release of some neutral and numerous monosialyl and disialyl oligosaccharides. These were fractionated by gel filtration, anion-exchange chromatography, and high-performance liquid chromatography. The structures of the monosialyl oligosaccharides were established by combination of sugar and methylation analysis, fast atom bombardment-mass spectrometry, and electron impact-mass spectrometry after permethylation and 1H NMR spectroscopy (at 500 MHz). Typically, some of the monosialyl oligosaccharides appeared to possess the core structure Gal beta(1----3)[GlcNAc beta(1----6)]GalNAc alpha(1----3)GalNAc-ol. Moreover, the (1----6)-linked branch consisted of an unusual di- or trigalactosyl sequence, [Gal alpha(1----4)0-1Gal beta(1----4)Gal beta (1----4)GlcNAc beta(1----6). Thus, the most complex representatives of the monosialyl fraction from Collocalia mucin were found to be: (Formula: see text) The other compounds identified are partial structures thereof.

Structure determination of the polymorphism of acylgalactosylceramide in rat brain by gas chromatography/mass spectrometry and proton magnetic resonance

This paper describes the structure of acylcerebrosides isolated from rat brains. Three fractions (acylglycosylceramides I, II, III) were resolved according to their decreasing RF values on TLC. GLC analysis of acylglycosylceramides II and III indicates that their ester-linked fatty acids are short and rather unsaturated, while amide-linked fatty acids are longer and hydroxylated. Sugar GLC analysis indicates that acylglycosylceramides II and III contain only galactose. To determine the substitution position of the acyl group on the galactose moiety, the free hydroxyl groups of acylglycosylceramide were protected with dihydropyran, deacylated and subjected to permethylation. The methylated galactoside acetates obtained after hydrolysis and reduction were then analyzed by gas chromatography/mass spectrometry. Acylglycosylceramides II and III turned out to be complex mixtures of 2-O-acyl-, 3-O-acyl-, 4-O-acyl- and 6-O-acylgalactosylceramides. Moreover, the abundance of alpha-methylgalactoside reveals the existence of unsubstituted galactose, suggesting that some ester-linked fatty acids could be esterified to the hydroxyl group of hydroxy fatty acids linked to sphingosine. NMR spectrometry was used to confirm this ester linkage. The key spectral feature of the fatty acid-galactose linkage (4.45 ppm) did move to 4.15 ppm after saponification of acylglycosylceramide II; on the other hand, acylglycosylceramide III contained only the spectral feature 4.15 ppm, corresponding to a high percentage of unsubstituted galactose and consistent with the presence in the molecule of a fatty acid esterified by the omega-OH group of the hydroxy fatty acid (3.95 ppm).

Catabolism of glycoprotein glycans. Characterization of a lysosomal endo-N-acetyl-beta-D-glucosaminidase specific for glycans with a terminal chitobiose residue

An endo-N-acetyl-beta-D-glucosaminidase active towards oligosaccharides with a reducing terminal [bis(N-acetylglucosamine)]residue has been characterized in rat liver. The primary structure of its reaction products was determined using high-resolution 1H-NMR spectroscopy. The enzyme is predominantly located in the lysosomal fraction, presents a maximum of activity at pH 3.5 and is completely inactive towards conjugated glycans, i.e. glycoproteins and glycopeptides as well as on glycoasparagines. These results support the existence of a new pathway for the degradation of glycoprotein glycans inside the lysosome. In particular, this enzymic activity may be the origin of oligosaccharides bearing a single terminal reducing N-acetylglucosamine residue which are excreted in the urine of patients with various exoglycosidase deficiencies.

Structure of two new oligosaccharides isolated from human milk: sialylated lacto-N-fucopentaoses I and II

The structures of two minor oligosaccharides isolated from human milk have been investigated. By using f.a.b.-mass spectrometry, methylation analysis, and partial formolysis as the principal methods of structural investigation, these oligosaccharides were identified as IV2-alpha-Fuc-III6-alpha-NeuAc-LcOse4 and IV3-alpha-NeuAc-III4-alpha-Fuc-LcOse4. This latter oligosaccharide has been recently found to be the carbohydrate moiety of a ganglioside isolated from a colorectal carcinoma cell-line (see ref. 12).

A novel type of carbohydrate structure present in hen ovomucoid

Hen ovomucoid is characterized by a high degree of microheterogeneity of its carbohydrate moieties, as was recently demonstrated by hydrazinolysis in combination with high performance liquid chromatography (Paz Parente, J., Strecker, G., Leroy, Y., Montreuil, J., and Fournet, B. (1982) J. Chromatogr., in press). This approach resulted in 17 oligosaccharide-alditol fractions; the major one could be purified to homogeneity. Primary structural analysis of this fraction was carried out by methylation analysis, partial acid hydrolysis, and 500-MHz 1H NMR spectroscopy. Combination of these techniques enabled the unambiguous determination of a novel type of asparagine-bound carbohydrate chain: (formula, see text).