Biomedical subjects

G Strecker

Publications and source records attributed to G Strecker.

At least 55 records · Page 3Linked to original sources

PubMed1996

Isolation and structures of glycoprotein-derived free oligosaccharides from the unfertilized eggs of Scyliorhinus caniculus. Characterization of the sequences galactose(alpha 1-4)galactose(beta 1-3)-N-acetylglucosamine and N-acetylneuraminic acid(alpha 2-6)galactose(beta 1-3)-N-acetylglucosamine.

As previously reported [Ishii, K., Iwasaki, M., Inoue, S., Kenny, P. T. M., Komura, H. & Inoue, Y. (1989) J. Biol. Chem. 264, 1623-1630; Inoue, S., Iwasaki, M., Ishii, K., Kitajima, K. & Inoue, Y. (1989) J. Biol. Chem. 264, 18520-185261, the unfertilized eggs of two different species of fresh-water fish, Plecoglossus altivelis and Tribodolon hakonensis, contain relatively large amounts of free sialooligosaccharides. These oligosaccharides were found to derive from glycophosphoproteins, owing to the activity of a peptide - N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase [Iwasaki, M., Seko, A., Kitajima, K., Inoue, Y. & Inoue, S. (1992) J. Biol. Chem. 267, 24287-24296; Seko, A., Kitajima, K., Inoue, Y. & Inoue, S. (1991) J. Biol. Chem. 266, 22110-22114]. Here we describe a new type of free oligosaccharides, isolated from unfertilized eggs of Scyliorhinus caniculus. From the structural analysis, based upon 1H-NMR spectroscopy, the following glycan units are proposed.[Formula: see text]

Animals↗

PubMed1996

A water-soluble beta-D-glucan from Boletus erythropus.

The main component of a water extract of Boletus erythropus fruiting bodies is a M(r) 10(6) glucan. The use of classical structural analysis and HMQC (heteronuclear multiple quantum coherence) NMR experiments indicates a (1-->3) linked beta-D-glucan structure with a single glucose residue attached to O-6 of the main chain and a branching frequency of 1/3.

Agaricales↗

PubMed1996

Lectin activities of cytokines and growth factors: function and implications for pathology.

The discovery that certain cytokines have carbohydrate-binding (lectin) properties opens new concepts in the understanding of their mechanism of action. The carbohydrate-recognition domain, which is localized opposite to the receptor-binding domain, makes these molecules bi-functional. The expression of the biological activity of the cytokine relies on its carbohydrate-binding activity which allows the association of the cytokine receptor with molecular complexes comprising the specific kinase involved in receptor phosphorylation and in specific signal transduction. It is expected that blood accumulation of free or membrane-bound glucan ligands of cytokines may dramatically perturb their endogenous function inducing specific immunodeficiencies.

Acquired Immunodeficiency Syndrome↗

PubMed1995

Structure of glycopeptides isolated from bovine milk component PP3.

The heat-stable acid-soluble phosphoglycoprotein component PP3 was isolated from the bovine milk proteose peptone fraction by concanavalin A affinity chromatography. Glycopeptides were released by pronase digestion of the milk component PP3 and were subsequently separated by high-pH anion-exchange chromatography on CarboPac PA-1. The primary structures of the glycan and peptide moieties of eight N-glycopeptides have been established by combining methylation analysis, mass spectrometry, 400-MHz 1H-NMR spectroscopy, and peptide sequence analysis. All the analyzed fractions contained biantennary N-acetyllactosamine-type carbohydrate chains, some of them with a GalNAc(beta 1-4)GlcNAc or a NeuAc(alpha 2-6)GalNAc(beta 1-4)GlcNAc group. This particular sequence did or did not replace the Gal(beta 1-4)GlcNAc group usually found in most N-linked glycans. Moreover, the sialylated Gal and GalNAc residues were only found on the Man(alpha 1-3) antenna.

Amino Acid Sequence↗

PubMed1995

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.

Ambystoma↗

PubMed1995

Structure of four acidic oligosaccharides from the jelly coat surrounding the eggs of Xenopus laevis.

Novel acidic oligosaccharides were released by reductive beta-elimination from the jelly coat eggs of the Anuran Xenopus laevis. According to the structural analysis of these oligosaccharide-alditols, the following structures are proposed: [sequence: see text] where Kdn, 3-deoxy-D-glycero-D-galactononulosonic acid. These results confirm the species specificity of the glycanic structures present in the secretion of amphibian oviducts, and may form the basis of a specific egg-sperm recognition process.

Animals↗

PubMed1995

Primary structure of acidic oligosaccharide-alditols derived from the jelly coat of Ambystoma tigrinum. Occurrence of oligosaccharides with fucosyl(alpha 1-5)[fucosyl(alpha 1-4)]-3-deoxy-D-glycero-D-galacto- nonulosonic acid and fucosyl (alpha 1-2) galactosyl (alpha 1-3)-N- acetylgalactosamine sequences.

Eleven O-glycosidic carbohydrate units derived from the jelly coat of Ambystoma tigrinum were analyzed by 1H-NMR spectroscopy. As previously shown for four other amphibian species, the glycans display a remarkable species specificity. As a characteristic feature, 3-deoxy-D-glycero-D-galacto-nonulosonic acid (Kdn) was found difucosylated at C4 and C5, and alpha-Gal attached to C3 of GalNAc-ol. The most representative carbohydrate units are: [formula: see text]

Ambystoma↗

PubMed1995

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).

Ambystoma↗

PubMed1995

Identification by NMR spectroscopy of oligosaccharides obtained by acidolysis of the capsular polysaccharides of a thermal biomass.

This study deals with the chemical characterization of a capsular polysaccharide (CPS) produced by a thermal biomass largely comprising the cyanobacterium Mastigocladus laminosus. The sugar moiety of this polymer is composed of seven neutral monosaccharides (Rha, Fuc, Ara, Xyl, Man, Glc, Gal) and two uronic acids (GalA, GlcA). Proteins represent 18% of the dry weight of the CPS. Organic acid substituents (acetate, pyruvate, succinate) were also detected and estimated by high-performance liquid chromatography. The presence of sulfate groups (5% w/w) was observed, which represents a relatively rare feature for cyanobacteria. Acidic hydrolysis of the purified polysaccharide led to the isolation of four oligosaccharidic fractions. NMR spectroscopy studies of two of the four purified oligosaccharides allowed them to be identified as: alpha-GlcA-(1-->2)-alpha-GalA-(1-->2)-Man and alpha-GlcA-(1-->2)-alpha-GalA-(1-->2)-beta-Man-(1-->4)-beta-Gal-(1 -->2)-Rha.

Bacterial Capsules↗

PubMed1995

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.

Animals↗

PubMed1995

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.

Amino Acids↗

PubMed1995

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.

Animals↗

PubMed1994

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.

Animals↗

PubMed1994

The core-specific lysosomal alpha(1-6)-mannosidase activity depends on aspartamidohydrolase activity.

The substrate specificity of the core-specific rat liver lysosomal alpha(1-6)-mannosidase was investigated using mannosylated oligosaccharides and glycoasparagines. Hydrolysis of Man(alpha 1-6) linkage hydrolysis was demonstrated to follow the action of endoglycosidases, namely aspartyl-N-acetyl-beta-D-glucosaminidase and endo-N-acetyl-beta-D-glucosaminidase. The results are discussed with respect to the nature of the carbohydrate materials stored in the tissues and excreted in the urine from patients suffering from aspartylglucosaminuria and fucosidosis.

Acetylation↗

PubMed1994

A fluorescence high-performance liquid chromatography assay for enzymes acting on the di-N-acetylchitobiosyl part of asparagine-linked glycans.

The glycoasparagine, Man7GlcNAc2Asn ('Man7') was labelled with resorufin and used as a specific substrate for the detection and quantification of endo-beta-N-acetyl glucosaminidases (Endos) acting on the di-N-acetylchitobiosyl part of asparagine-linked glycans. Peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine amidases (PNGases) cannot transform this substrate but they can be detected by the procedure described earlier using the resorufin-labelled N-glycopeptide [Glycoconjugate J., 9 (1992) 162-167]. These two substrates can be used in a simple, reproducible and very sensitive fluorescence HPLC assay in order to monitor Endo and PNGase activities during isolation and purification processes, or studies of the evolution of such activities during cultivation of the producing cells.

Carbohydrate Conformation↗

PubMed1994

Crosslinking of mammalian lectin (galectin-1) by complex biantennary saccharides.

Galectins are beta-galactoside-binding proteins that occur intra- and extracellularly in many animal tissues. They have been proposed to form networks of glycoconjugates on the cell surface, where they may modulate various cell response pathways such as growth, activation and adhesion. The high resolution X-ray crystallographic analyses of three crystal forms of bovine galectin-1 in complex with biantennary saccharides of N-acetyllactosamine type reveal infinite chains of lectin dimers cross-linked through N-acetyllactosamine units located at the end of the oligosaccharide antenna. The oligosaccharide adopts a different low energy conformation in each of the three crystal forms.

Amino Acid Sequence↗

PubMed1994

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.

Ambystoma↗

PubMed1993

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.

Carbohydrate Conformation↗