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PubMed1983

Immunochemical studies on Shigella dysenteriae type 9 bacterial polysaccharide.

On graded hydrolysis and Smith degradation, the O-somatic polysaccharide isolated from Shigella dysenteriae type 9 bacteria, strain NCTC 7919, yielded five oligosaccharides which were characterized. The positions of the O-acetyl and pyruvic acetal groups in the repeating unit were identified. Immunochemical studies indicated that D-galactose is the immunodominant sugar in the polysaccharide, and one of the oligomers, having the structure Gal-(1 leads to 3)-GlcNAc-(1 leads to 3)-Gal-(1 leads to 4)-Man, showed maximum inhibition of the homologous precipitation.

Antigen-Antibody Complex↗
PubMed1984

Synthesis and characterization of some anomeric pairs of per-O-acetylated aldohexopyranosyl cyanides (per-O-acetylated 2,6-anhydroheptononitriles). On the reaction of per-O-acetylaldohexopyranosyl bromides with mercuric cyanide in nitromethane.

The synthesis and characterization of the anomeric pairs of the per-O-acetylaldohexopyranosyl cyanides of D-galactose, L-fucose, D-glucose, and D-mannose, as well as of 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl cyanide, are described. Cyanation of the readily available, per-O-acetylaldohexopyranosyl bromides with mercuric cyanide in nitromethane, and subsequent purification, gave the corresponding, crystalline glycosyl cyanides with a high degree of 1,2-trans stereoselectivity. Thus, per-O-acetylated aldohexopyranosyl cyanides of the 1,2-trans configuration were obtained in yields ranging from 20 to 79%, whereas the corresponding 1,2-cis anomers were obtained in yields of less than or equal to 8.4%, the ratios of the 1,2-trans:1,2-cis anomers so prepared being greater than or equal to 8.5:1. The principal by-products of these irreversible, cyanation reactions were the per-O-acetylated 1,2-O-[1-(exo- and endo-cyano)ethylidene]aldohexopyranoses, obtained in yields of up to 40%. The structural assignments of the per-O-acetylaldohexopyranosyl cyanides were unequivocally established by elemental analysis, chemical transformation, vibrational spectroscopy, and 13C- and 1H-nuclear magnetic resonance spectroscopy. Correlations between the physical properties and the anomeric configurations of these C-aldohexopyranosyl compounds are described.

Chemical Phenomena↗
PubMed1984

Synthesis of 2-acetamido-2-deoxy-4-O-beta-D-galactopyranosyl-3-O-methyl -D-glucopyranose (N-acetyl-3-O-methyllactosamine) and its benzyl alpha-glycoside.

Benzyl 2-acetamido-2-deoxy-3-O-methyl-alpha-D-glucopyranoside (3) was obtained by deacetalation of its 4,6-O-benzylidene derivative (2). Compound 2 was prepared by methylation of benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-alpha-D-glucopyranoside with methyl iodide-silver oxide in N,N-dimethylformamide. Diol 3 was selectively benzoylated and p-toluenesulfonylated, to give the 6-benzoic and 6-p-toluenesulfonic esters (4 and 5, respectively). Displacement of the sulfonyl group of 5 with sodium benzoxide in benzyl alcohol afforded the 6-O-benzyl derivative (6). Glycosylation of 4 with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide (7) in dichloromethane, in the presence of 1,1,3,3-tetramethylurea, furnished the disaccharide derivative 8. Similar glycosylation of compound 6 with bromide 7 gave the disaccharide derivative 10. O-Deacetylation of 8 and 10 afforded disaccharides 9 and 11. The structure of compound 9 was established by 13C-n.m.r. spectroscopy. Hydrogenolysis of the benzyl groups of 11 furnished the disaccharide 2-acetamido-2-deoxy-4-O-beta-D-galactopyranosyl-3-O-methyl-D-glucopyr ano se (N-acetyl-3-O-methyllactosamine).

Amino Sugars↗
PubMed1984

Synthetic mucin fragments: methyl 3-O-(2-acetamido-2-deoxy-beta-D-galactopyranosyl-beta-D- 3-O-(2-acetamido-2-deoxy-3-O-beta-D-galactopyranosyl- beta-D-glucopyranosyl)-beta-D-galactoyranoside. pyranosyl)-beta-D-galactopyranoside.

Methyl 2,4,6-tri-O-benzyl-beta-D-galactopyranoside (5) was obtained crystalline by way of its 3-O-allyl derivative, which was in turn obtained by ring-opening of a presumed 3,4-O-stannylene derivative of methyl beta-D-galactopyranoside, followed by benzylation. Condensation of 5 with 2-methyl-(2-acetamido-3,4,6-tri-O-acetyl-1,2-dideoxy-beta-D-glucopyra no)-[2,1-d]-2-oxazoline in 1,2-dichloroethane in the presence of p-toluenesulfonic acid afforded the disaccharide derivative methyl 3-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucopyranosyl)-2, 4,6-tri-O-benzyl-beta-D-galactopyranoside (6) Deacetylation of 6 in methanolic sodium methoxide afforded the disaccharide derivative 7, which was acetalated with alpha, alpha-dimethoxytoluene to afford the 4',6'-O-benzylidene acetal (10). Catalytic hydrogenolysis of the benzyl groups of 7 afforded the title disaccharide 8. Glycosylation of 10 with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide in 1:1 benzene-nitromethane in the presence of mercuric cyanide gave the fully protected trisaccharide derivative 12. Systematic removal of the protecting groups of 12 then furnished the title trisaccharide 14. The structures of 5, 8, and 14 were all confirmed by 13C-n.m.r. spectroscopy. The 13C-n.m.r. chemical shifts for methyl alpha- and beta-D-galactopyranoside, and also those of their 3-O-allyl derivatives, are recorded, for the sake of comparison, in conjunction with those of compound 5.

Carbohydrate Conformation↗
PubMed1984

Synthesis of N-(1-deoxyhexitol-1-yl)amino acids, reference compounds for the nonenzymic glycosylation of proteins.

The N-(1-deoxy-D-mannitol-1-yl) and N-(1-deoxy-D-glucitol-1-yl) derivatives of L-valine, L-alanine, L-threonine, and L-leucine were prepared by reductive amination of D-mannose and D-glucose with the appropriate amino acids, in the presence of sodium cyanoborohydride. N epsilon-(1-Deoxy-D-mannitol-1-yl)- and N epsilon-(1-deoxy-D-glucitol-1-yl)-L-lysine were prepared by similar reactions of hexoses with N alpha-tert-butoxycarbonyl and N alpha-benzyloxycarbonyl-L-lysine, followed by removal of the protecting groups. The structures were confirmed by 1H-n.m.r. spectroscopy, which showed that each compound was completely free of its C-2 epimer. The synthetic compounds may be used as reference compounds for the identification of N-(1-deoxyhexitol-1-yl)amino acids formed when N-(1-deoxy-D-fructose-1-yl) groups of nonenzymically glycosylated proteins, of the hemoglobin A1c type, are reduced with sodium borohydride, and the protein is subjected to acid-catalyzed hydrolysis.

Amino Acids↗
PubMed1984

Synthesis of 5-amino-5-deoxy-D-mannopyranose and 1,5-dideoxy-1,5-imino-D-mannitol, and inhibition of alpha- and beta-D-mannosidases.

The title compounds and the corresponding L-gulo derivatives were synthesised in 6 steps from benzyl 2,3:5,6-di-O-isopropylidene-alpha-D-mannofuranoside. The Ki values, determined from inhibition studies with alpha-D-mannosidases from jack beans, almonds, and calf liver, and beta-D-mannosidase from Aspergillus wentii, ranged from 70 to 400 microM for the mannitol derivative and from 1.2 to 20 microM for 5-amino-5-deoxy-D-mannopyranose, i.e., inhibition is 10(2)-10(4)-fold stronger than with D-mannose. Marked enhancement of inhibition with increasing pH is ascribed to the ionisation of a carboxyl group at the active site, forming an ion pair with the protonated inhibitor. The inhibition equilibrium between the jack-bean enzyme and the mannose derivative was approached slowly with kapp 2.0 X 10(5) M-1 X min-1. The mannose-derived inhibitor was also inhibitory against beta-D-glucosidases from almonds and Asp. wentii, with Ki values only 20-150-times larger than those for the inhibition of these enzymes by 5-amino-5-deoxy-D-glucopyranose. This moderate discrimination in binding of D-gluco and D-manno derivatives is in marked contrast to the high specificity shown by the glucosidase in catalysing the hydrolysis of mannosidases. A similar low specificity with respect to binding, combined with highly specific catalysis, was also seen with the mannosidases acting on inhibitors and substrates with the D-gluco configuration.

1-Deoxynojirimycin↗
PubMed1984

Synthesis and characterization of methyl 6-O-alpha- and -beta-D-galactopyranosyl-beta-D-galactopyranoside.

Sequential tritylation, acetylation and detritylation of methyl beta-D-galactopyranoside gave crystalline methyl 2,3,4-tri-O-acetyl-beta-D-galactopyranoside (4) and methyl 2,3,6-tri-O-acetyl-beta-D-galactopyranoside, the latter being the minor product resulting from acetyl migration. Reaction of 4 with 2,3,4,6-tetra-O-acetyl-alpha-D-galactosyl bromide in benzene, in the presence of mercuric cyanide and mercuric bromide, gave the alpha- and beta-D-(1----6)-linked disaccharides (7 and 9, respectively) in high yield, and their structure was confirmed by 1H- and 13C-n.m.r. 1d. and 2d. spectroscopy. O-Deacetylation of 7 gave the hitherto unknown, crystalline methyl 6-O-alpha-D-galactopyranosyl-beta-D-galactopyranoside. O-Deacetylation of 9 gave the corresponding, beta-D-linked disaccharide methyl glycoside, the physical constants of which are discussed with respect to controversial data in the literature.

Carbohydrate Conformation↗
PubMed1984

S-, N-, and O-glycosyl derivatives of 2-acetamido-2-deoxy-D-glucose with hydrophobic aglycons as potential chemotherapeutic agents and N-acetyl-beta-D-glucosaminidase inhibitors.

S-, N-, and O-Glycosyl derivatives of 2-acetamido-2-deoxy-D-glucose with hydrophobic aglycons have been obtained as potential, plasma-membrane active agents. 2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-1-thio-beta-D-glucopyranose (6) was converted into benzyl, diphenylmethyl, triphenylmethyl, and other thioglycosides. Acylation of 6 gave adamantoyl and haloacetyl derivatives. A similar series of N- and O-glycosyl derivatives was obtained from the corresponding NH2-1 and OH-1 analogs of 6, such as O- and N-dinitrophenyl, O- and N-adamantoyl, and N-4-methylbenzylidene derivatives. Several N- and S-glycosyl derivatives were found to inhibit mouse mammary adenocarcinoma (TA3) cells in vitro as well as N-acetyl-beta-D-glucosaminidase from beef liver.

Acetylglucosaminidase↗
PubMed1984

The synthesis of a trisaccharide and a tetrasaccharide lipid intermediate. P1-dolichyl P2-[O-beta-D-mannopyranosyl-(1----4)-O-(2-acetamido-2-deoxy- beta-D-glucopyranosyl)-(1----4)-2-acetamido-2-deoxy-alpha-D- glucopyranosyl] diphosphate and P1-dolichyl P2-[O-alpha-D-mannopyranosyl-(1----3)-O-beta-D- mannopyranosyl-(1----4)-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)- (1----4)-2-acetamido-2-deoxy-alpha-D-glucopyranosyl] diphosphate.

Synthetic benzyl O-(2,3,4,6,-tetra-O-acetyl-beta-D-mannopyranosyl)-(1-4)- (2-acetamido-3,6-di-O-acetyl-2-deoxy-beta-D-glucopyranosyl)-(1-4)- 2-acetamido-3,6-di-O-benzyl-2-deoxy-alpha-D-glucopyranoside was converted, by catalytic hydrogenolysis of the benzyl groups, followed by treatment with acetyl chloride-hydrogen chloride and then "chloride-ion catalysis", into O-(2,3,4,6-tetra-O-acetyl- beta-D-mannopyranosyl)-(1-4)-O-(2-acetamido-3,6-di-O-acetyl-2-deoxy beta- D-glucopyranosyl)- (1-4)-2-methyl-(3,6-di-O-acetyl-1,2-dideoxy-alpha-D- glucopyrano)-[2,1-d]-2-oxazoline. This compound was phosphorylated by treatment with dibenzyl phosphate under strictly anhydrous conditions to give after catalytic hydrogenolysis, a peracetyl trisaccharide phosphate. This was coupled with P1-dolichyl P2-diphenyl diphosphate to give, after O-deacetylation, P1-dolichyl P2-[O- beta-D-mannopyranosyl- (1-4)-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)- (1-4)-2-acetamido-2-deoxy-alpha-D-glucopyranosyl] diphosphate, a trisaccharide "lipid intermediate". O-(2,3,4,6-Tetra-O-acetyl-alpha-D-mannopyranosyl)-(1-3)-O-(2,4,6-tri-O- acetyl-beta-D-mannopyranosyl)-(1-4)-O-(2-acetamido-3,6-di-O-acetyl-2- deoxy-beta- D-glucopyranosyl)- (1-4)-(2-acetamido-3,6-di-O-acetyl-2-deoxy-alpha-D-glucopyranosyl) phosphate, synthesized from O-alpha-D-mannopyranosyl-(1-3)-O-beta-D- mannopyranosyl-(1-4)-2-acetamido-2-deoxy-D-glucopyranose that had been isolated from mannosidosis urine was coupled with P1-dolichyl P2-diphenyl diphosphate to give, after O-deacetylation, P1-dolichyl P2-[O-alpha-D-mannopyranosyl- (1-3)-O-beta-D-mannopyranosyl-(1-4)-O-(2-acetamido-2-deoxy-beta-D- glucopyranosyl)-(1-4)-2-acetamido-2-deoxy-alpha-D-glucopyranosyl] diphosphate, a tetrasaccharide "lipid intermediate".

Chromatography, Thin Layer↗
PubMed1984

Synthetic mucin fragments: benzyl 2-acetamido-6-O-(2-acetamido-2-deoxy-beta- D-glucopyranosyl)-2-deoxy-3-O-beta-D-galactopyranosyl-alpha-D- galactopyranoside and benzyl 2-acetamido-6-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)- 3-O-[6-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-beta-D- galactopyranosyl]-2-deoxy-alpha-D-galactopyranoside.

Glycosylation of benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-alpha-D- galactopyranoside with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide, catalyzed by mercuric cyanide, afforded benzyl-2-acetamido-4,6-O-benzylidene-2-deoxy-3- O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-alpha-D- galactopyranoside (3). O-Deacetylation of 3 gave benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-3-O-beta- D-galactopyranosyl-alpha-D-galactopyranoside which, on acetalation with benzaldehyde-zinc chloride complex followed by acetylation of the resulting dibenzylidene acetal, gave the disaccharide diacetate (7). Cleavage of the acetal groups of 3 and 7 in hot, 80% aqueous acetic acid furnished, respectively, the disaccharide tetraacetate (4) and diacetate (8). O-Deacetylation of 8 in methanolic sodium methoxide gave the disaccharide (9). Condensation of 4 or 8 with 2-methyl-(3,4,6-tri-O-acetyl-1,2- dideoxy-alpha-D-glucopyrano)-[2,1-d]-2-oxazoline, followed by O-deacetylation, afforded the title tri- and tetra-saccharides, 12 and 14, respectively. The structures of compounds 9, 12, and 14 were established by 13C-n.m.r. spectroscopy.

Indicators and Reagents↗