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Structure of the oligosaccharide portion of human hepatitis B surface antigen.

The hepatitis B surface antigen, which constitutes the currently available vaccine, is the empty envelope of the hepatitis B virus. We investigated the carbohydrate structures of the envelope glycoproteins. The intact oligosaccharides were enzymatically released from the coat glycoproteins using peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine amidase F and isolated by gel permeation chromatography. Cesium ion liquid secondary ion mass spectra of the intact, underivatized oligosaccharides showed molecular weights of 1932, 2078, and 2223. The mixture included partially and totally sialylated structures, a fraction (approximately 8%) of which were substituted with a single terminal fucose residue; no desialylated oligosaccharides were detected. The reducing termini of the oligomers were derivatized by reduction of the Schiff base formed using p-aminobenzoic acid ethyl ester, and fragmentation patterns identical to those produced from standard biantennary complex oligosaccharides were obtained. Methylation linkage analysis of the oligosaccharides showed that the carbohydrate composition and the mannose branching patterns also resembled those of a biantennary oligosaccharide. The results of this study indicate that glycosylation of the hepatitis B surface antigen, which takes place in the liver, is typical of other serum glycoproteins made in the liver; and this analytical strategy, including cesium ion liquid secondary ion mass spectrometry, is an effective approach for the structural analysis of complex carbohydrates available in only the 1-10 micrograms sample size range.

Chromatography, High Pressure Liquid↗

Structure and location of asparagine-linked oligosaccharides in the Fc region of A human immunoglobulin D.

Seven kinds of asparagine-linked oligosaccharides were bound to the Fc region of a human immunoglobulin D(NIG-65). The oligosaccharides quantitatively released from four species of glycopeptides by digestion with almond glycopeptidase, were separated by Bio-Gel p-4 column chromatography and were purified further by thin-layer chromatography. The sugars were identified with GC-MS following the permethylation of respective oligosaccharide. To Asn-68 (NIG-65 Fc numbering (1)), two kinds of high-mannose-type oligosaccharides were bonded. To Asn-159, a kind of hybride-type and two kinds of bisected complex-type oligosaccharides were attached. From Asn-210, four kinds of bisected complex-type oligosaccharides were isolated.

Animals↗

The accumulation of oligosaccharides in tissues and body fluids of cats with alpha-mannosidosis.

Oligosaccharides were extracted from tissues and body fluids of five kittens with alpha-mannosidosis, three being from the same litter. The kittens were all of different ages at death and were compared to normal and heterozygote cats. The oligosaccharides were analyzed by high-pressure liquid chromatography after perbenzoylation and were identified by comparison with compounds of known structure. This provided a detailed picture of the distribution of oligosaccharides in each tissue, and a method for quantitation of the total oligosaccharides. With the exception of the youngest animal (death at day 2), the oligosaccharide elution profiles were broadly similar for all tissues and fluids, and were typical of feline alpha-mannosidosis. In contrast, concentrations of total oligosaccharides diverged widely from one source to another, from a high of 17.3 mumol/g to a low of 0.04 mumol/g. The results are interpreted in the context of glycoprotein catabolism.

Animals↗

Oligosaccharides from faeces of a blood-group B, breast-fed infant.

Eight oligosaccharides have been isolated from faeces of a blood group B, secretor, breast-fed infant and characterized by sugar and methylation analysis, f.a.b. mass spectrometry and 1H-n.m.r. spectroscopy. One of these oligosaccharides has not previously been reported and is a tri-L-fucosyl derivative of lacto-N-hexaose. The other compounds were identical to oligosaccharides found in human milk. Several of the reported compounds require the secretor dependent 2'-fucosyltransferase for their biosynthesis. Since the mother of this child was an O(H) non-secretor, an intestinal biosynthesis of at least some of these compounds is strongly indicated. No blood group B active oligosaccharides were detected which is in sharp contrast to the oligosaccharide excretion in faeces from a blood group A infant [Sabharwal et al., Mol. Immunol., 21 (1984) 1105-1112] in which all the major oligosaccharides isolated were blood group A active.

ABO Blood-Group System↗

Study of structurally defined oligosaccharide substrates of heparin and heparan monosulfate lyases.

The rapid preparation of multimilligram quantities of five heparin-derived oligosaccharides (1-5) is described. These oligosaccharides are the final products obtained from the action of heparin lyase (heparinase, E.C. 4.2.2.7) at its primary sites in the heparin polymer. Five oligosaccharides comprise from 75-85 wt% of commercial porcine mucosal heparins and are recovered in good yield and high purity. Four of these five oligosaccharides were further acted upon at much lower rates by prolonged treatment with heparin lyase or heparan monosulfate lyase (heparitinase, E.C. 4.2.2.8), revealing the subspecificities of these enzymes. These oligosaccharides were used as defined substrates for heparin lyase and heparan monosulfate lyase and their kinetic constants were obtained. Potential applications for these oligosaccharides include their use as defined substrates for purification of heparin monosulfate lyases, and for establishing the catalytic purity of enzyme preparations.

Carbohydrate Sequence↗

Separation of yeast asparagine-linked oligosaccharides by high-performance anion-exchange chromatography.

Oligosaccharides obtained from Saccharomyces cerevisiae mannoproteins by digestion with endo-N-acetyl-beta-D-glucosaminidase H were fractionated by anion-exchange chromatography, by elution with 50-100mM NaOH without or with a sodium-acetate gradient, and detected with a pulsed amperometric detector (PAD). The elution times of homologous oligosaccharides fell on a straight line having a slope characteristic of the structural type. The response of the PAD detector per mole of oligosaccharide increased about 2-fold going from Man3GlcNAc to Man13GlcNAc, and appeared to depend primarily on the oxidation of the reducing-end N-acetylglucosamine unit common to all the oligosaccharides. The digestion of a Man10GlcNAc with jack-bean alpha-mannosidase was monitored by injecting portions of the crude reaction mixture, and the intermediates were characterized by their elution positions and n.m.r. spectra in the anomeric proton region. One commercial jack-bean alpha-mannosidase preparation contained a novel endolytic activity that released N-acetylglucosamine from the reducing ends of the oligosaccharides and was shown to convert P----6 alpha Man----6 alpha Man----6 beta Man----4 alpha beta GlcNAc to P----6 alpha Man----6 alpha Man----6 alpha beta Man plus free N-acetylglucosamine. Another commercial jack-bean alpha-mannosidase converted the Man10GlcNAc to a Man3GlcNAc having the structure alpha Man----6 beta Man----4 alpha beta GlcNAc, [formula: see text] whereas the Oerskovia sp. alpha-mannosidase converted the same oligosaccharide to a Man4GlcNAc having the structure alpha Man----6 alpha Man----6 beta Man----4 alpha beta GlcNAc. [formula: see text]

Alkaline Phosphatase↗

Structural analysis of monosulfated side-chain oligosaccharides isolated from human tracheobronchial mucous glycoproteins.

To determine the location of some sulfate esters on respiratory mucins, an unambiguous sequencing strategy was developed for a crude, monosulfated oligosaccharide fraction derived from tracheobronchial mucous glycoproteins, isolated from sputum from a patient with cystic fibrosis, and which possessed Ricinus communis-I lectin affinity. Employing fractionation by Bio-Gel P-2 chromatography and high-voltage paper electrophoresis of the pool, eighteen branched and four straight-chained monosulfated oligosaccharides, each possessing at least one neutral D-galactose residue at a nonreducing terminus, were purified. Desulfated analogs of each sulfated oligosaccharide were then produced. Elucidation of their structures and sulfate ester locations was accomplished through a parallel comparative sequencing approach for the sulfated oligosaccharide and its desulfated analog. The method was based on their carbohydrate composition and parallel analysis by sequential exoglycosidase degradations, endoglycosidase digestion, permethylation analyses, and specific lectin affinities. Key to this approach was the inability for specific exoglycosidases and lectins to cleave or bind to, respectively, carbohydrates of their specificity which occupied nonreducing termini and possessed a sulfate ester. Herein we report the structures of twenty-two novel sulfated oligosaccharides. Oligosaccharides ranged from trisaccharides to heptasaccharides, were branched and unbranched, and each possessed a single sulfate ester on either C-6 of a terminal or an internal D-galactose residue or on C-6 of an internal residue of 2-acetamido-2-deoxy-D-glucose (N-acetyl-D-glucosamine).

Bronchi↗

Characterization of the oligosaccharide structures on bee venom phospholipase A2.

The N-linked oligosaccharide structures on bee venom phospholipase A2 were investigated. The oligosaccharides on purified phospholipase A2 were released by hydrazinolysis and labeled in vitro by reduction with NaB3H4. Following purification, the labeled oligosaccharides were characterized by size exclusion chromatography in combination with digestion with specific glycosidases. Linkage positions were determined by methylation analysis. Four types of structures were identified on the molecule, all of which were of truncated high-mannose type and none of which contained any alpha-(1-->2)-linked mannose residues. The majority of the structures were Man3 oligosaccharides with (43%) or without (38%) a fucose residue linked alpha-(1-->6) to the reducing N-acetylglucosamine. The remaining 19% of the oligosaccharides on the molecule were identified as a Man5 oligosaccharide without core fucose (9.6%) and a core-fucosylated Man4 structure (9.2%).

Bee Venoms↗

Metabolism of xyloglucan generates xylose-deficient oligosaccharide subunits of this polysaccharide in etiolated peas.

Oligosaccharide subunits of xyloglucan were isolated from the stems and roots of etiolated pea plants and structurally characterized. The two most abundant subunits of pea xyloglucan are the well-known nonasaccharide, XXFG, and heptasaccharide, XXXG. In addition, significant amounts of oligosaccharides that have not previously been reported to be subunits of pea xyloglucan were detected, including a decasaccharide, XLFG, two octasaccharides, XLXG and XXLG, a pentasaccharide, XXG, and a trisaccharide, XG. Several novel oligosaccharide subunits, including the octasaccharide, GXFG, and the hexasaccharide, GXXG, were also found. Xyloglucan oligosaccharides generated by treatment of intact pea stem cell walls were compared to oligosaccharides generated by endoglucanase treatment of xyloglucan polysaccharides obtained by subsequent alkali extraction of the same cell walls. The results suggest that the xyloglucan in etiolated pea stems is distributed between at least two domains, one of which is distinguished by its enzyme accessibility. We further hypothesize that the chemical modification of a xyloglucan during cell-wall maturation depends on its physical environment (i.e., the domain in which it resides). For example, only the endoglucanase-released material, representing the enzyme-accessible xyloglucan domain, contains significant amounts of the two unusual oligosaccharide subunits, GXXG and GXFG, both of which have a nonreducing terminal glucosyl residue. This structure may be generated during cell-wall maturation by the sequential action of an endolytic enzyme (such as xyloglucan endotransglycosylase or endoglucanase) and an alpha-xylosidase.

Carbohydrate Sequence↗

Improved protocol for the formation of N-(p-nitrobenzyloxy)aminoalditol derivatives of oligosaccharides.

An improved procedure has been developed for the rapid derivatization of oligosaccharides with UV-detectable p-nitrobenzylhydroxylamine (PNB). The improved conditions used result in quantitative derivatization of neutral oligosaccharides. Sialylated oligosaccharides can also be quantitatively PNB-derivatized without detectable desialylation. Of the oligosaccharides tested, only the derivatization of oligogalactosyluronic acids was incomplete (yield approximately 70%). PNB-derivatization of tamarind seed xyloglucan oligosaccharides results in products with improved chromatographic properties during HPAEC. These PNB derivatives were also subjected to hydrophilic interaction chromatography (HILIC) and analyzed by on-line LC-MS. On-line LC-MS is readily usable with HILIC, as this chromatographic technique does not require salt-containing solvents. Approximately 10 pmol of a PNB-derivatized oligosaccharide can be identified and quantitated utilizing this method.

Carbohydrate Conformation↗

Diagnosis and characterization of GM 2 gangliosidosis type II (Sandhoff disease) by analysis of the accumulating N-acetyl-glucosaminyl oligosaccharides with high performance liquid chromatography.

The N-acetyl-glucosaminyl oligosaccharides excreted in urine and accumulating in tissues of Sandhoff disease patients have been analyzed and characterized using a combination of high performance liquid chromatography and 500 MHz proton magnetic resonance spectroscopy. Delineation between infantile and juvenile onset forms of the disease was possible, as the latter forms had 6- to 13-fold lower levels of urinary oligosaccharides. Patients from a geographically isolated population deme in the La Rioja region of Argentina had urinary oligosaccharides similar to unrelated non-Argentinean patients with identical clinical phenotype. Together, these results indicate that the urinary oligosaccharides serve as useful indicators of the mutation differences or clinical heterogeneity within this disease only in cases of markedly differing clinical presentation. Analysis of the accumulating metabolites in liver, kidney, pancreas, lung and spleen, showed a similar oligosaccharide pattern which differed dramatically from brain. These results suggest the possibility of tissue specific regulation of oligosaccharide biosynthesis since there are notable differences between neural and visceral tissues.

Acetylglucosamine↗

Severity of GM1 gangliosidosis and urinary oligosaccharide excretion.

Urinary oligosaccharides of GM1 gangliosidosis patients (type 2A, 4 cases; type 2B, 2 cases) were investigated using the Bio Gel system. The levels of urinary oligosaccharide excreted (nmol/mg creatinine) by the type 2A patients were 4.1 times the levels of the type 2B patients. Patients of type 2A excreted high molecular weight oligosaccharides which were not detected in the urine of type 2B, and excreted oligosaccharides with long linkages of repeating structures. Thus, type 2A apparently has biochemically different characteristics from type 2B related to urinary oligosaccharide. Differentiation of type 2A from type 2B can thus be made biochemically. The structures of 5 different kinds of oligosaccharides not reported previously were confirmed.

Adolescent↗

Reversibility of monensin inhibition of oligosaccharide processing of human fibronectin.

Monensin impairs oligosaccharide processing in fibronectin primarily by inhibiting the conversion of oligosaccharides from the high mannose type to the complex type. The separate effects of monensin and cations on alpha-mannosidase activity in fibroblasts were examined using an in vitro assay system. The results indicated that monensin did not directly inhibit alpha-mannosidase activity in vitro, although prior treatment of fibroblasts with monensin caused an irreversible suppression of enzyme activity. The reversibility of monensin action on oligosaccharide processing was also examined. Analyses using concanavalin A (ConA) Sepharose affinity chromatography showed that the inhibitory action of monensin on oligosaccharide processing was biologically reversible. A progressive return to complex type oligosaccharides began about 11 h after the removal of the monensin. These composite results indicate that the reversibility of monensin action on oligosaccharide processing in fibronectin may be attributed to the restoration of enzyme activity, although the mechanism by which restoration occurs remains to be deciphered.

Calcium↗

Use of a porous graphitised carbon column for the high-performance liquid chromatography of oligosaccharides, alditols and glycopeptides with subsequent mass spectrometry analysis.

HPLC using a porous graphitised carbon (PGC) column eluted in acetonitrile-aqueous trifluoroacetic acid has been shown to give complementary chromatography to reversed-phase (ODS) HPLC for separation of peptides and glycopeptides. The PGC column can also be used for separation of oligosaccharides and oligosaccharide alditols released from protein by enzymes (N-linked chains) or base-borohydride degradation (O-linked chains). The advantages are that peptides, glycopeptides, reducing oligosaccharides, sialylated oligosaccharides and oligosaccharide alditols can be chromatographed under the same conditions. The samples can be readily recovered by evaporation for sensitive liquid secondary ion mass spectrometric (LSI-MS) analysis and there is no contamination or deterioration of chromatography from column leakage. LSI-MS analysis revealed that complete peak separation of all of the possible oligosaccharide components of the standard glycoproteins fetuin and bovine submaxillary mucin was not achieved. However, PGC remains as a useful adjunct to other HPLC profiling and separation techniques in particular where subsequent MS analysis is desired.

Amino Acid Sequence↗

Multi-dimensional mapping of pyridylamine-labeled N-linked oligosaccharides by capillary electrophoresis.

A simple, sensitive and reproducible multi-dimensional capillary electrophoresis (CE) oligosaccharide mapping method is reported. The structures of 20 identified N-linked oligosaccharides have been assigned mapping positions from which co-migrating unknown oligosaccharides can be characterized. The separation protocols developed have been demonstrated to separate both charged and neutral oligosaccharides. One dimension involves electroendosmotic flow-assisted CE in a sodium acetate buffer, pH 4.0. A second dimension involves separation based on borate complexation electrophoresis in a polyethylene glycol-containing buffer. A third dimension developed specifically for neutral oligosaccharides, using a sodium phosphate buffer, pH 2.5, has been shown to resolve neutral species not able to be separated by the other two dimensions. Thus, a three-dimensional map was generated to facilitate structural characterization of these oligosaccharides.

Aminopyridines↗

Preparative purification of tyrosinamide N-linked oligosaccharides.

N-linked oligosaccharides from glycoproteins can be either analyzed on a sub-nanomole scale or preparatively purified on a multi-micromole scale. Each goal necessitates a unique analytical strategy often involving oligosaccharide derivatization to enhance separation and detection. Tyrosinamide-oligosaccharides were developed to facilitate the preparative purification of N-linked oligosaccharides. These have found many uses in oligosaccharide remodeling, in the preparation of neoglycoconjugates, in developing receptor probes, and even as analytical standards in chromatography. This review discusses progress in the preparation of tyrosinamide-oligosaccharides from different glycoproteins and their utility in glycobiology research.

Carbohydrate Conformation↗

Capillary electrophoretic examination of underivatized oligosaccharide mixtures released from immunoglobulin G antibodies and CTLA4Ig fusion protein.

A procedure is presented for the separation of underivatized oligosaccharides by capillary electrophoresis (CE) with a phytic acid-borate buffer system. The presence of the phytic acid ion-pairing agent greatly increases resolution between oligosaccharides in the complex mixtures studied, which was demonstrated by the separation of oligosaccharides originating from various immunoglobulin G antibodies and CTLA4Ig, a biologic fusion protein. The conditions also resolve neutral oligosaccharides, usually a major CE limitation. High-performance anion-exchange chromatography with pulsed amperometric detection, a standard technique for oligosaccharide and sugar analysis, is used as a reference method to analyze some of the complex oligosaccharide mixtures.

Abatacept↗

Processing of gPr92env, the precursor to the glycoproteins of Rous sarcoma virus: use of inhibitors of oligosaccharide trimming and glycoprotein transport.

A number of aspects of the processing of gPr92env, the precursor to the viral glycoproteins gp85 and gp35 of Rous sarcoma virus (RSV), have been studied. First, the kinetics of gPr92env processing have been examined, revealing that the precursor is overproduced in the infected cell and only a small percentage (less than 5%) is converted into mature glycoprotein in virus particles. Second, the effects of inhibitors of intracellular transport (monensin) and oligosaccharide trimming (N-methyl-1-deoxynojirimycin (MdN) and bromoconduritol (BC) ) on the processing of gPr92env have been examined. It could be shown with all three inhibitors that proteolytic cleavage of gPr92env could occur although oligosaccharide trimming was inhibited. The aberrant cleavage products, gp75mon and gp30mon, produced in the presence of monensin, carry oligosaccharides where only 1-3 mannose residues have been removed in comparison to the precursor gPr92env (this latter carries predominantly Man9(GlcNAc)2). Virus particles containing the aberrant glycoproteins were released in virtually normal amounts and were infectious. In the presence of MdN and BC, viral glycoprotein precursors carrying three (MdN) or one (BC) glucose on the high-mannose oligosaccharide could be detected intracellularly. The aberrant precursors could be proteolytically cleaved to gp80MdN and gp75BC which are equivalent to gp85 but carry the smaller glucose-containing high-mannose oligosaccharides instead of the large, complex, sialidated oligosaccharides of mature glycoprotein. In the presence of MdN, the abnormal glycoproteins were incorporated into virions which were fully infectious.

1-Deoxynojirimycin↗