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Biomedical subjects

B Fournet

Publications and source records attributed to B Fournet.

At least 73 records · Page 4Linked to original sources
PubMed1986

Effect of phenobarbital on the oligosaccharide structure of rat alpha-acid glycoprotein.

We have recently shown that the administration of phenobarbital to rats leads to an increased serum alpha 1-acid glycoprotein content with alterations in the relative proportion of the sugar moiety. Therefore, alpha 1-acid glycoprotein was purified from normal (alpha 1-acid glycoproteine N) and phenobarbital-treated rats (alpha 1-acid glycoprotein PB) Glycans were separated by AX-10 chromatography and analysed by gas chromatography. It appears that, compared to alpha 1-acid glycoprotein N, alpha 1-acid glycoprotein PB had a higher carbohydrate content (31.7% compared to 26%) and a non-negligible amount of neutral oligosaccharide (12.2% compared to 1.3%). No tetrasialyl oligosaccharides in alpha 1-acid glycoprotein PB were detected, whereas their relative proportion in alpha 1-acid glycoprotein N was 27%.

Animals↗
PubMed1985

Structural analysis of the carbohydrate chains of beta-N-acetylhexosaminidases from bovine brain.

The oligosaccharide structures of bovine brain beta-N-acetylhexosaminidases A and B (EC 3.2.1.30) were studied at the glycopeptide level by employing 500 MHz 1H-n.m.r. spectroscopy and methylation analysis involving g.l.c.-m.s. More than 90% of the chains were found to be of the oligomannoside type, containing, on average, five to six mannose residues. Biantennary N-acetyl-lactosamine-type chains terminated in N-acetylneuraminic acid were found to comprise the remaining 5-10% of the total carbohydrate. The isoenzyme forms A and B do not differ from each other in the structure of their carbohydrate moiety, but do deviate in carbohydrate content and, in consequence, in the number of carbohydrate chains per molecule.

Animals↗
PubMed1985

Comparative study of glycophorin A derived O-glycans from human Cad, Sd(a+) and Sd(a-) erythrocytes.

Glycophorin A was purified from the erythrocyte membranes of blood group Cad, Sd(a+) and Sd(a-) donors and the oligosaccharide alditols, obtained after alkaline borohydride degradation, separated by h.p.l.c. on an alkylamine silica gel column, were characterized by sugar analysis. Structure determination of the major acid components by methylation analysis, g.l.c.-m.s. and 1H-n.m.r. indicated that the three blood group Cad red cells under study (samples Cad., Bui. and Des.) carry the same pentasaccharide GalNAc(beta 1-4)[NeuAc(alpha 2-3)]Gal(beta 1-3)[NeuAc(alpha 2-6)]GalNAc -ol(Cad determinant) but in different amounts. This pentasaccharide, however, was absent from glycophorin A of Sd(a+) and Sd (a-) donors, suggesting that the Sda determinant is not associated with glycophorins. It was calculated that glycophorin A from the original Cad donor (Cad.) carries about 12 O-glycosidically linked pentasaccharide chains per molecule whereas only 2-3 of these chains were present in the samples from the two other unrelated Cad individuals (Bui. and Des.) It is well known from quantitative agglutination studies that the proportion of red cells which can be agglutinated by the Dolichos biflorus lectin varies from one Cad blood sample to another. Some are completely agglutinated (Cad. donor) whereas others are only partially agglutinated (Bui. and Des. donors) suggesting that some red cells might not carry the Cad determinants. From the results presented above and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis studies it is suggested that Cad red cells from Bui. and Des. do not carry a mixture of glycophorin A molecules with or without the Cad pentasaccharides but a spectrum of glycoprotein molecules with varying amounts of Cad determinants.

Blood Group Antigens↗
PubMed1985

A convenient method for methylation of glycoprotein glycans in small amounts by using lithium methylsulfinyl carbanion.

Treatment of dimethyl sulfoxide with butyllithium leads to rapid formation of lithium methylsulfinyl carbanion. The reaction products tend to be significantly freer from impurities when lithium methylsulfinyl carbanion is used rather than sodium or potassium methylsulfinyl carbanion. This reagent gives less background in g.l.c. and thus may be used to methylate micro-quantities of glycoprotein glycans (down to 10 micrograms) without the necessity of identifying methyl ethers by mass spectrometry.

Animals↗
PubMed1985

Structure determination of oligosaccharides isolated from Cad erythrocyte membranes by permethylation analysis and 500-MHz 1H-NMR spectroscopy.

Alkaline borohydride reductive cleavage (beta-elimination) of glycophorin A isolated from one individual of the rare blood group Cad, resulted in the release of six acidic oligosaccharide-alditols which were separated by high-performance liquid chromatography (HPLC) on an alkyl amine silicagel column. The structure of four of them has been determined by the application of methanolysis, methylation analysis and 1H-NMR spectroscopy at 500 MHz. The structures and relative amounts were as follows: oligosaccharide 1: NeuAc(alpha 2-3)Gal(beta 1-3)GalNAc-ol (3.5%); oligosaccharide 3: GalNAc(beta 1-4)[NeuAc(alpha 2-3)]Gal(beta 1-3)GalNAc-ol (10.5%); oligosaccharide 5: NeuAc(alpha 2-3)Gal(beta 1-3)[NeuAc(alpha 2-6)]GalNAc-ol (10.4%); oligosaccharide 6: GalNAc(beta 1-4)[NeuAc(alpha 2-3)]Gal(beta 1-3)[NeuAc(alpha 2-6)]GalNAc-ol (71.2%). The two other oligosaccharides (2 and 4) were obtained in very low amount. The major pentasaccharide (oligosaccharide 6) carries the blood group Cad determinant and is a potent inhibitor of human anti-Sda antibody.

Blood Group Antigens↗
PubMed1984

Biosynthesis of blood group I antigens. Identification of a UDP-GlcNAc:GlcNAc beta 1-3Gal(-R) beta 1-6(GlcNAc to Gal) N-acetylglucosaminyltransferase in hog gastric mucosa.

A beta 1-6N-acetylglucosaminyltransferase has been identified in microsomal preparations from hog gastric mucosa which is able to synthesize branch points in branched lactosaminoglycans (blood group I antigenic structures). The enzyme can be assayed specifically using the synthetic trisaccharide GlcNAc beta 1-3Gal beta 1-4Glc beta-OMe as acceptor. The product of the transferase reaction was isolated and identified by methylation analysis as, (Formula: see text) Into this tetrasaccharide two galactose residues were incorporated by the specific beta-N-acetylglucosaminide beta 1-4-galactosyltransferase from bovine milk. Thus a hexasaccharide was formed which was shown to inhibit strongly a murine monoclonal and a human anti-I antibody. Using a variety of oligosaccharides and glycolipids, which correspond to structures found in linear lactosaminoglycan chains, the acceptor substrate specificity of the branching enzyme was determined. From these results it is concluded that branching occurs only during the elongation process at the nonreducing end and follows a well-defined order. N-Acetylglucosamine is first transferred to position 3 of a terminal galactose followed immediately by the addition of a second N-acetylglucosamine to position 6; only then the 1-3 and the 1-6 branches are further elongated by galactose residues.

Animals↗
PubMed1984

Separation of sialyl-oligosaccharides by high-performance liquid chromatography. Application to analysis of carbohydrate units of acidic oligosaccharides obtained by hydrazinolysis of hen ovomucoid.

Sialyl- oligossacharides derived from hen ovomucoid by hydrazinolysis have been separated by liquid chromatography on quaternary amine bonded silica and alkylamine modified silicas . By using a mobile phase consisting of a mixture of acetonitrile and potassium dihydrogen phosphate with 0.01% of 1,4- diaminobutane , effective resolution of high-molecular-weight monosialylated oligossacharides was achieved in less than 2 h.

Animals↗
PubMed1983

Primary structure of the oligosaccharide determinant of blood group Cad specificity.

Glycophorin A and B from Cad erythrocyte membranes are the carriers of the blood group Cad determinants. They are characterized by a significant increase in molecular mass, as compared to the corresponding glycophorins from control erythrocytes (Cartron, J.-P., and Blanchard, D. (1982) Biochem. J. 207, 497-504). Lipid-free glycophorin A, purified from Cad red cells, showed an increased GalNAc content in comparison to blood group B, Cad-negative, control cells. Alkaline-borohydride treatment of this Cad glycophorin A released as a predominant species a pentasaccharide; its structure was determined, by methylation analysis and by 500-MHz 1H-NMR studies, to be: (formula; see text) This novel oligosaccharide inhibited strongly the hemagglutination of Cad erythrocytes by the Dolichos biflorus lectin. It shares with the blood group Sda determinant a terminal GalNAc beta (1 leads to 4)Gal beta (1 leads to .) sequence.

Blood Group Antigens↗
PubMed1983

Carbohydrate structures of hen ovomucoid. A mass spectrometric analysis.

The apparently homogenous N-glycosidically-linked glycans 1, 7, 11 and 14 released by hydrazinolysis from hen ovomucoid were analysed by fast atom bombardment and electron-impact mass spectrometry after reduction and permethylation. The spectra support the primary structures established independently [FEBS Letters (1983) 152, 145-152] using methylation analysis, partial acid hydrolysis and 500 MHz 1H NMR spectroscopy. In addition to the major constituents present in fractions 1, 7, 11 and 14, four minor components not detected by other methods could be characterized with the aid of the mass spectrometry data as: Man2GlcNAcGlcNAc-o1, GlcNAc4Man3GlcNAc-o1, GlcNAc6Man3GlcNAc-o1 and GalGlcNAc6-Man3GlcNAc-o1. Our results show that the physical techniques used provide valuable data on the structure of complex glycans. In addition they can be employed to ascertain the homogeneity of the compounds examined as well as to detect trace amounts of homologs that might not be noticed by other methods.

Animals↗
PubMed1983

Primary structure of a novel N-glycosidic carbohydrate unit, derived from hen ovomucoid. A 500-MHz 1H-NMR study.

The N-glycosidic carbohydrate chains of hen beta-ovomucoid were released from the protein by hydrazinolysis, and separated by HPLC. Primary structural analysis of 3 major fractions was conducted by applying 500-MHz 1H-NMR spectroscopy in combination with methylation analysis. One of the fractions investigated appeared to consist of an intersected penta-antennary structure extended with one Gal residue. The location of the latter in a certain branch could be established unambiguously by NMR. This structure is a novel member of the family of N-glycosidic carbohydrates of glycoproteins.

Animals↗
PubMed1982

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).

Animals↗
PubMed1982

Primary structure of the glycans from human lactotransferrin.

The polypeptide chain of human lactotransferrin possesses two glycoslyation sites to which glycans are linked through an N-(beta-aspartyl)-N-acetylglucosaminylamine bond and which are structurally heterogenous. After chymotryptic or pronase digestions, glycopeptides with five different glycan structures could be isolated. For three of them, the structure has been determined by the application of methanolysis, methylation analysis, hydrazinolysis/nitrous deamination, enzymatic cleavage and 1H-NMR spectroscopy at 360 MHz: Glycopeptides A and B: 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-)Asn; Glycopeptide C: NeuAc(alpha 2-6)(Gal(beta 1-4)GlcNAc(beta 1-2)Man(alpha 1-3)(Gal(beta 1-4)[Fuc(alpha 1-3)]GlcNAc(beta 1-2)Man(alpha 1-6))Man(beta 1-4)GlcNAc(beta 1-4)[Fuc(alpha 1-6)]GlcNAc(beta 1-)Asn. Glycopeptide D: NeuAc(alpha 2-6)Gal(beta 1-4)GlcNAc(beta 1-2)Man(alpha 1-3)[Gal(beta 1-4)GlcNAc(beta 1-2)Man(alpha 1-6)]Man(beta 1-4)Glc-NAc(beta 1-4)[Fuc(alpha 1-6)]GlcNAc(beta 1-)Asn. Two other glycopeptides were obtained in very low amount and possess more complex structures.

Chemical Phenomena↗
PubMed1982

Discrimination between activity of (alpha 2-3)-sialyltransferase and (alpha 2-6)-sialyltransferase in human platelets using p-nitrophenyl-beta-D-galactoside as acceptor.

Exogenous asialo-glycoproteins and endogenous acceptors are both sialylated by incubating cytidine 5'-monophosphate N-[14C]acetylneuraminic acid (CMP [14C]NeuAc) with a lysate of human platelets but their respective incorporation levels vary with the divalent cation concentration. P-Nitrophenyl-beta-D-galactoside has also been demonstrated to be an acceptor of sialyl residues, and two different sialyl derivatives are synthesized according to the concentration of divalent cations. P-Nitrophenyl-beta-D-[6-3H]galactoside has been prepared by reduction with tritiated borohydride of the compound previously oxidized by galactose oxidase. Using this labelled p-nitrophenyl-beta-D-galactoside as acceptor and unlabelled CMP-NeuAc as donor, the two sialyl derivatives have been identified by methylation analysis as alpha-sialosyl-(2-3)-p-nitrophenyl-beta-D-galactoside and alpha-sialosyl-(2-6)-p-nitrophenyl-beta-D-galactoside. In addition to their different responses to divalent cation requirements, the sialyltransferase activities responsible for the synthesis of the two sialylgalactoside isomers have been clearly distinguished by their temperature and pH optimal values. They also exhibit different susceptibilities to dithioerythritol and different stabilities. These results demonstrate the presence in human platelets of two sialyltransferases: a CMP-NeuAc: galactoside (alpha 2-3)-sialyltransferase and a CMP-NeuAc: galactoside (alpha 2-6)-sialyltransferase.

Blood Platelets↗
PubMed1982

[Immunomodulating properties of an extract isolated and partially purified from Aloe vahombe. 3. Study of antitumoral properties and contribution to the chemical nature and active principle].

An immuno-modulator fraction (Alva) extracted from an endemic plant, in the south of Madagascar, the Aloe vahombe, significantly protects mice against bacterial, parasitic and fungal infections. Wishing to verify whether the fraction Alva was active in tumour reduction, we studied its effect on the development of experimental fibrosarcoma and melanoma in mice by intravenous and intracutaneous injections and injections directly into the tumour of the immunostimulant fraction. We have observed cures, only in the case of the McC3-1 tumour but it is encouraging to note that under different experimental conditions the rate of growth of tumours in animals which were treated is slower than in those not treated. The Alva fraction is a substance which is hydrosoluble, thermostabile, having a molecular weight exceeding 30 000 and is a polysaccharide. The predominant sugars are glucose and mannose in 3:1 ratio. Preliminary studies of its action seem to indicate that the Alva fraction acts upon non-specific response and could possibly stimulate the phagocyte activity of the peritoneal macrophagus.

Aloe↗
PubMed1981

Structure determination of oligosaccharides isolated from A+, H+ and A-H- hog-submaxillary-gland mucin glycoproteins, by 360-MHz 1H-NMR spectroscopy, permethylation analysis and mass spectrometry.

Alkaline borohydride reductive cleavage (beta-elimination) of hog submaxillary glycoproteins from three immunologically determined phenotypes, viz. A+, H+ and A-H-, resulted in the release of a series of neutral and acidic oligosaccharide-alditols. 360-MHz 1H-NMR spectroscopy in combination with methylation analysis and mass spectrometry were used for reinvestigation of the structures of these oligosaccharide-alditols. All are partial structures representing the possible complete and biosynthetically incomplete stages of the chain of a pentasaccharide-N-acetylgalactosaminitol, present in the glycoprotein with blood-group-A activity: (formula: see text) In this way, a prolonged argument about the occurrence of a NeuGc(alpha 2 leads to 6) Gal moiety in these carbohydrate chains, suggested by Aminoff et al. [Aminoff, D., Baig, M. M. and Gathmann, W. D. (1979) J. Biol. Chem. 254, 1788-1793 and 8909-8913] has been brought to a definite end. In the investigated oligosaccharide-alditols N-glycoloylneuraminic acid (NeuGc) is in no case attached to galactose (Gal), but, if present, it is (alpha 2 leads to 6)-linked to N-acetylgalactosaminitol (GalNAc-ol).

Animals↗
PubMed1981

Characterization of the microheterogeneity in glycoproteins by 500-MHz 1H-NMR spectroscopy of glycopeptide preparations. Application to a monofucosylated tetra-antennary glycopeptide fraction from human plasma alpha 1-acid glycoprotein.

Five hundred-MHz 1H-NMR spectroscopy was employed to study a monofucosylated tetra-antennary glycopeptide fraction which was derived from human plasma alpha 1-acid glycoprotein. This fraction was earlier judged to be homogeneous by 360-MHz 1H-NMR spectroscopic analysis (Fournet, B., Montreuil, J., Strecker, G., Dorland, L., Haverkamp, J., Vliegenthart, J. F. G., Binette, J. P., and Schmid, K. (1978) Biochemistry 17, 5206-5214). The combination of the improved resolving power and the enhanced sensitivity of the 500-MHz 1H-NMR spectrometer afforded the elucidation of a new type of microheterogeneity with regard to the position of attachment of Fuc. Three isomeric compounds were identified. The major form contains Fuc alpha-(1 leads to 3) linked to GlcNac 7 of the tetra-antennary structure, as shown earlier. The two minor compounds, representing new structures, possess Fuc attached in alpha-(1 leads to 3) linkage to GlcNAc 7' or 5'. It is thus noteworthy that this spectral technique allows elucidation of structures of very closely related carbohydrate chains in a glycopeptide mixture.

Carbohydrate Conformation↗