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References to other databases: GTC:G07295LF, GlycomeDB:26786
Structural formula & atomic coordinates
Sweet-II 3D model
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The antigenic recognition of Shigella flexneri O-polysaccharide, which consists of a repeating unit ABCD [→2)-α-L-Rhap-(1→2)-α-L-Rhap-(1→3)-α-L-Rhap-(1→3)-β-D-GlcpNAc-(1→], by the monoclonal antibody SYA/J6 (IgG3, kappa) has been investigated by crystallographic analysis of the Fab domain and its two complexes with two antigen segments (a pentasaccharide Rha A-Rha B-Rha C-GlcNAc D-Rha A' and a modified trisaccharide Rha B-Rha C-GlcNAc D in which Rha C is missing a C2-OH group). These complex structures, the first for a Fab specific for a periodic linear heteropolysaccharide, reveal a binding site groove (between the V(H) and V(L) domains) that makes polar and nonpolar contacts with all the sugar

Lipopolysaccharide, antigen, oligosaccharide, structure, repeating unit, trisaccharide, analysis, group, molecular, X-ray, Shigella flexneri, antibodies, antibody, epitope, monoclonal, monoclonal antibodies, monoclonal antibody, recognition, complex, epitopes, O-polysaccharide, O polysaccharide, specific, sugar, modified, Shigella, pentasaccharide, antigenic, binding, binding site, domain, domains, FAB, heteropolysaccharide, linear, molecular recognition, polar, site, thermodynamics

NCBI PubMed ID: 12427018
Journal NLM ID: 0370623
Publisher: American Chemical Society
Correspondence: faq@bcm.tmc.edu
Institutions: Verna and Marrs Mclean Department of Biochemistry and Molecular Biology and Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030, Departments of Chemistry and of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6, Department of Chemistry, University of Alberta, Edmonton, AB, Canada
Methods: crystallography, thermodynamics

Chloromethoxylation of di-O-acetyl-L-rhamnal has been employed as a convenient route to methyl 3,4-di-O-acetyl-2-chloro-2-deoxy-α-L-rhamnopyranoside 7, which was converted into an ethyl thioglycoside 10, suitable for use as a glycosyl donor. It and a disaccharide analogue 20 were effective donors in N-iodosuccinimide-triflic acid promoted glycosylations of a 2-acetamido-2-deoxy-D-glucopyranoside acceptor 22. Chlorodeoxy saccharides have previously been shown to be suitable derivatives to probe oligosaccharide-protein interactions, and this synthetic strategy provided three monochlorodeoxy trisaccharide congeners of the native Shigella flexneri epitope 2, α-L-Rhap-(1→3)-α-L-Rhap-(1→3)-β-D-GlcNAcp-(1→O)-Me.

synthesis, polysaccharide, trisaccharide, Shigella flexneri, derivative, Shigella, Trisaccharides

NCBI PubMed ID: 7693346
Journal NLM ID: 0043535
Publisher: Elsevier
Institutions: Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario.
Methods: 13C NMR, 1H NMR, NMR-2D, TLC, chemical methods

A series of di- and trisaccharide glycosides based on the α-L-Rha(1→3)β-D-GlcNAc and α-L-Rha(1→3)α-L-Rha(1→3)β-D-GlcNAc elements have been synthesized to locate the minimal oligosaccharide determinant of the Shigella flexneri O-polysaccharide, which is built from a tetrasaccharide repeating unit, [→2)α-L-Rhap(1→2)α-L-Rhap(1→3)α-L-Rhap(1→3)β-D-GlcNAcp(1-]n. These compounds also serve to identify the carbohydrate surface of the Shigella antigen that interacts with a monoclonal antibody, currently the subject of crystallographic studies. Two strategies utilizing suitably protected glycals 1 and 19 were employed to obtain analogs bearing either terminal or glycosylated 2,6-dideoxy-α-L-arabino-hexopyranosyl (2-deoxy-α-L-rhamnopyranosyl) residues. N-Iodosuccinimide activation of the glycals in the presence of selectively protected mono- and disaccharide alcohols afforded 2-deoxy-2-iodo-α-L-rhamnopyranosides and these were ultimately reduced during deprotection stages to afford the desired functionality. Di-O-acetyl L-rhamnal 1 reacted with monosaccharides 2 and 7, and with disaccharide 11, to yield disaccharides 4 and 8, and trisaccharide 12, each bearing a terminal 2-deoxy-α-L-rhamnopyranosyl residue. The selectively protected 3-O-benzoyl-4-O-benzyl-L-rhamnal 19 was synthesized from L-rhamnal and used to prepared trisaccharide 22, which contained an internal 2-deoxy-2-iodo-α-L-rhamnopyranosyl unit. Removal of protecting groups gave the oligosaccharides 6, 10, 14, and 23. Oligosaccharides that contained a 2-deoxy-α-L-rhamnopyranosyl residue showed enhanced inhibitory power: in the case of trisaccharide 23 a 1.8 kcal/mol relative increase in free energy of binding compared to a larger pentasaccharide epitope, α-L-Rhap(1→2)α-L-Rhap(1→3)α-L-Rhap(1→3)β-D-GlcNAcp(1→2)α-L-Rhap-1→OMe. These data suggest that the rhamnose O-2 hydroxyl of residue C points toward and has important interactions with binding site amino acids.

synthesis, Shigella flexneri, monoclonal antibodies, O-polysaccharide, binding site, antigen-antibody interaction, 2-deoxy-L-rhamnose

Publication DOI: 10.1139/v93-018
Journal NLM ID: 0372705
Publisher: National Research Council of Canada Canada
Institutions: Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6 Canada
Methods: 13C NMR, 1H NMR, TLC, ELISA, chemical methods, serological methods