Synthesis of a fucosylated and a non-fucosylated core structure of xylose-containing carbohydrate chains from N-glycoproteins (original) (raw)
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Synthesis of Four Structural Elements of Xylose Containing Carbohydrate Chains from N-Glycoproteins
2000
The synthesis of the oligosaccharides P-D-Xylp-(l-+2)-P-D-Manp-OMe (12), P-D-Xylp-(1+2)-(cY-D-Manp-(l-+6))-fi-D-Manp-OMe (17), /3-D-Xylp-(l-+2)-((Y-D- Manp-(l-+3))-P-D-Manp-OMe (21), and P-D-Xylp-(l-+2)-(cr-D-Manp-(I+3)l(cr-D- Manp-( 1+6))-@-D-Manp-OMe (25) is described. Methyl 3-O-benzyl4,6-O-iso- propylidene-/3-D-mannopyranoside (6) was prepared from the corresponding gfuco- epimer (4) by oxidation, followed by stereoselective reduction. Condensation of 6 with 2,3,4-tri-O-acetyl-au-D-xylopyranosyl bromide in the presence of mercuric cyanide gave a 1:9 mixture of methyl 3-O-benzyl-4,6-O-isopropylidene-2-O-(2,3,4-
Carbohydrate Research, 1986
Glycoproteins containing N-linked oligosaccharides are ubiquitous on cell surfaces. While all of these saccharides contain an invariant core-structure, the structures of their arms vary widely2. Even if the biological significance of these variations is unclear, it is certain that they are capable of influencing the overall shape of the oligosaccharide molecule3. As an aid in the study of the threedimensional structures in solution of biologically derived, N-linked oligosaccharides by n.m.r. spectroscopy, we have synthesized several model compounds. These compounds aid in the interpretation of n.m.r. spectra of the larger, more complex glycopeptides in two ways. Firstly, *H-n.m.r. spectra of the model tri-and tetra-saccharides are simple enough to permit complete assignments, which then allows n.0.e. values in the spectra of the larger compounds to be assigned by analo&. Secondly, the synthetic compounds can be prepared with t3C (cf. lit5) or 2H (cf. lit.6) labels to aid in the conformational studies. We describe here the synthesis of a tetrasaccharide 2 that is a part of a carbohydrate structure 1. The methoxyl group usually interferes with the observation of ring-proton signals and consequently perdeuterated methoxyl was used.
Carbohydrate Research, 1988
In a previous paper in this series2, we outlined our interest in the synthesis of some oligosaccharides containing ~-fume a-(1+3)-link4 to 2-acetamido&deoxy-~glucose. Our interest in this class of compounds was, to a large extent, motivated by a desire to obtain reference compounds in studies related to (1+3)-CAL-fucosyltransferase. This interest was, however, enhanced by recent reports associating a variety of such oligosaccharide suuctures with certain types of human ca11cers3-~.
A short synthesis of the trisaccharide building block of the N-linked glycans
Tetrahedron Letters, 2003
An efficient preparation of the core trisaccharide of N-linked glycoproteins containing b-azido functionality at the reducing terminus is described. In the synthesis, triflate-mediated direct b-mannosylation was employed for the formation of the b-D-Man-(14)-GlcNAc linkage; the anomeric azide installation was achieved through oxazoline ring opening.
Glycosylation Pathways in Glycoprotein Biosynthesis
2002
Six purified glycosyltransferases (a P-galactoside cu2 + 6 sialyltransferase, a fi-galactoside ~y2 + 3 sialyltransferase, an a-N-acetylgalactosaminide a2 + 6 sialyltransferase, a fi-galactoside (~1 -+ 2 fucosyltransferase, a P-N-acetylglucosaminide al --+ 3 fucosyltransferase, and a (fucosyl cul + 2) galactoside (~1 ---f 3 N-acetylgalactosaminyltransferase) have been used to study the biosynthetic pathways for formation of the nonreducing terminal oligosaccharide sequences in mammalian glycoproteins. The two glycoproteins used as model acceptor substrates in this study were human asialotransferrin, which contains the nonreducing terminal oligosaccharide sequence Galfil + 4GlcNAcPl+ 2Man, and antifreeze glycoprotein, which contains oligosaccharides with the structure, Gal/X + 3GalNAccul-+ OThr. Sequential action of the six glycosyltransferases on these model substrates led to the formation of previously described oligosaccharide structures. The studies reported here indicate that the...