Stéphane Bouquelet

Etude chimique des mannosides urinaires excrétés au cours de la mannosidose

Summary Mannose-rich oligosaccharides have been isolated from urines of 5 patients with mannosidosis. Their composition and structure were determined. Three of them have been previously described by Norden et al.: α- d -Manp-(1 → 3) β- d -Mapp-(1 → 4) d -GlcNAcp; α- d -Manp-(1 → 2) α- d -Mapp-(1 → 3) β- d -Manp-(1 → 4) d -GlcNAc and α- d -Manp-(1 → 2) α- d -Manp-(1 → 2) α- d -Manp-(1 → 3) β- d -Manp-(1 → 4) d -GlcNAcp, but the four others are new entities: α- d -Manp-(1 → 3) [α- d -Manp-(1 → 2) α- d -Manp-(1 → 2) α- d -Manp-(1 → 6)] β- d -Manp-(1 → 4) GlcNAcp; α- d -Manp-(1 → 2) α- d -Manp-(1 → 3) [α- d -Manp-(1 → 2) α- d -Manp-(1 → 2) α- d -Manp-(1 → 6)] β- d -Manp-(1 → 4) GlcNAcp; [α- d -Manp-(1 → 2)4 α- d -Manp-(1 → 3) [α- d -Manp-(1 → 6)] β- d -Manp-(1 → 4) GlcNAcp and α- d -Manp-(1 → 2)]5 α- d -Manp-(1 → 3) [α- d -Manp-(1 → 6)] β- d -Manp-(1 → 4) GlcNAcp. These structures are related to the glycans of «oligomannosidic type present in numerous glycoproteins. All possess a N-acetylglucosamine residue in terminal reducing position and reinforce the hypothesis of Kobata et al. and Montreuil et al. that catabolism of glycans N-glycosidically linked to the protein moiety begins by the action of a β-endo-N-acetylglucosaminidase.

Primary structure of ten galactosides formed by transglycosylation during lactose hydrolysis by Bifidobacterium bifidum.

Oligosaccharides formed by a transgalactosylation reaction during lactose hydrolysis with Bifidobacterium bifidum were separated into eight fractions by gel-permeation chromatography and their structures studies determined by trimethylsilylation analysis, methylation analysis, f.a.b.-m.s., g.l.c.-m.s. and enzymic hydrolysis as beta-D-Galp-(1----3)-D-Glc, beta-D-Galp-(1----6)-D-Glc, beta-D-Galp-(1----6)-D-Gal, beta-D-Galp-(1----3)-beta-D-Galp-(1----4)-D-Glc, beta-D-Galp-(1----6)[beta-D-Galp-(1----4)]-D-Glc, beta-D-Galp-(1----2)[beta-D-Galp-(1----6)]-D-Glc, beta-D-Galp-(1----3)-beta-D-Galp-(1----3)-beta-D-Galp-(1----4)-D-Glc, beta-D-Galp-(1----3)-beta-D-Galp-(1----3)-beta-D-Galp-(1----3)-beta-D-Ga lp- (1----4)-D-Glc, beta-D-Galp-(1----3)-beta-D-Galp-(1----3)-beta-DGalp-(1----3)-beta -D-Galp-(1----3)-beta-D-Galp-(1----4)-D-Glc, and beta-D-Galp-(1----3)-beta-D-Galp-(1----3)-beta-D-Galp-(1----3)-beta-D-Ga lp-(1----3)-beta-D-G-alp-(1----3) beta-D-Galp-(1----4)-D-Glc.

Properties of a β-d-mannosidase from Aspergillus niger

Abstract The β- d -mannosidase (β- d -mannoside mannohydrolase, EC 3.2.1.25) from culture filtrate of Aspergillus niger has been purified in large amounts by fractionation with (NH4)2SO4 and DEAE-cellulose chromatography. The removal of traces of α- d -galactosidase was performed on a Sepharose-ϵ-aminocaproylgalactosylamine column. The final enzyme preparation (specific activity 188 units) has no other glycosidase activity and is judged homogeneous. The enzyme has a molecular weight of 130 000 ± 5000 and an isoelectric point of 4.7. The amino acid composition of the enzyme is characterized by high proportion of acidic amino acids and no cysteine residues and a single chain structure of the enzyme is suggested. The enzyme shows maximum activity on p- nitrophenyl -β- d - mannopyranoside at pH 3.5 and 55°C. The presence of 80% of β-sheet structure in the protein and 20.8% of monosaccharides (Gal : 1.3; Man : 7; GlcNAc : 1) could explain this relative high heat stability (up to 2 h at 55°C). Enzyme activity is inhibited by mannose (Ki = 7.85 mM) and the specificity is examined.

Characterization of a novel endo-N-acetyl-β-d-glucosaminidase from the culture filtrate of a basidiomycete (Sporotricum dimorphosporum), active on biantennary mono- and asialoglycoasparagines of the N-acetyllactosaminic type

A novel endo-N-acetyl-beta-D-glucosaminidase has been characterized in a culture filtrate from a Basidiomycete. This enzyme hydrolyses biantennary monosialo and asialo-glycoasparagines of the N-acetyllactosaminic type. Endo-N-acetyl-beta-D-glucosaminidase from the Basidiomycete released from different glycoasparagines, beta-GlcNAc-(1 leads to 4)-N[14C] acetyl-Asn, alpha Fuc-(1 leads to 6)-beta-GlcNAc-(1 leads to 4)-N-[14C]acetyl-Asn and oligosaccharides which have been separated by paper and thin-layer chromatography. Determination of the radioactivity of the labeled fragments leads to the conclusion that the biantennary glycoasparagines of the N-acetyllactosaminic type are hydrolyzed after 1 h incubation at 37 degrees, to the extent of 15 per cent for the monosialo; 90 per cent for the asialo; 21 per cent for the asialo-monofucosylated, and 15 per cent for the asialo-difucosylated glycans. Tri- and tetraantennary asialo-glycans of the N-acetyllactosaminic type are not hydrolyzed by this enzyme.

Étude sur les glycoprotéines. XLIX. Isolement et structure des oligosaccharides de la fraction neutre des acétolysats de glycopeptides de l'ovomucoïde

Abstract Thirteen oligosaccharides were isolated from the neutral fraction of the acetolysis product of asialoglycopeptide β, which had been obtained by pronase hydrolysis of avian ovomucoid. The structures of the oligosaccharides are as follows: O -2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→4)- D -mannopyranose; O -β- D -galactopyranosyl-(1→4)-2-acetamido-2-deoxy- D -glucopyranose; O -2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→2)- D -mannopyranose; O -α- D -mannopyranosyl-(1→3)- D -mannopyranose; O -2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→3)- O -[2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→2)]- D -mannopyranose; O -2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→4)- O -[2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→2)- D -mannopyranose; O -2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→4)- O -α- D -mannopyranosyl-(1→3)- D -mannopyranose; O -2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→2)- O -α- D -mannopyranosyl-(1→3)- D -mannopyranose; O -α- D -mannopyranosyl-(1→3)- O -[2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→4)]- D -mannopyranose; O -2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→2)- O -α- D -mannopyranosyl- O -[2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→4)]- D -mannopyranose; O -2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→4)- O -[2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→2)]- O -α- D -mannopyranosyl-(1→3)- D -mannopyranose; O -2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→4)- O -α- D -mannopyranosyl-(1→3)- O -[2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→4)- D -mannopyranose; O -2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→4)- O -[2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→2)]- O -α- D -mannopyranosyl-(1→3)- O -[2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→4)]- D -mannopyranose. p>-mannopyranose.

Determination de la structure d'un heptasaccharide isole du lait de femme: Le lacto-N-fucoheptaose

A new heptasaccharide, lacto‐N‐fucoheptaose has been isolated from human milk. It contains D(+)‐galactose, D(+)‐glucose, L(−)‐fucose and N−acetyl−D−(+)−glucosamine in a 3 : 1 : 1 : 2 ratio. The glucose residue is at the reducing end of the oligosaccharide. Data obtained by partial acid hydrolysis, permethylation and enzymic hydrolysis establish the structure of lacto‐N‐fucoheptaose as follows

Hydrolysis of Various Oligosaccharides and a Glycopeptide Core Derived from Glycoproteins by N-Acetyl-β-D-hexosaminidases A and B Isolated from Human Liver

Publisher Summary This chapter discusses the hydrolysis of various oligosaccharides and a glycopeptides core derived from glycoproteins by N -acetyl-β-d-hexosaminidases A and B isolated from human liver. This enzyme is involved in the hydrolysis of glycolipids and glycosaminoglycans. The chapter illustrates the hydrolysis of oligosaccharides having a single and two terminal GlcNAc residue by N -acetyl-β-hexosaminidases A and B. The results suggest that N -acetyl-β-hexosaminidases A and β could both be involved in the hydrolysis of oligosaccharides arising during glycoprotein catabolism by the concerted action of sialidase, β-galactosidase, and endo- N -acetyl-β-glucosaminidase. They may also be involved in the hydrolysis of glycopeptides with appropriate terminal sugars but at a low rate.