Matched and mismatched acceptor/donor pairs in the glycosylation of a trisaccharide diol free at O-3 of two N-acylated glucosamine residues.
Reciprocal donor acceptor selectivity (RDAS) and double diastereodifferentiation are two concepts that have been used to explain how a glycosyl acceptor and donor may be 'matched' or 'mismatched' in glycosylation reactions. We describe here how the α-L-fucosylation and β-D-galactosylation of a trisaccharide displaying two equatorial OH groups at C-3 of N-acylated glucosamine units led to different regioselectivities or different 'matched' pairs. These results may be explained under the reciprocal donor acceptor selectivity or double diastereodifferentiation concepts. We also suggest a third explanation to these results: the presence of a benzylidene at the nonreducing end acceptor led to rigidity at this residue which resulted into a mismatched pair during β-D-galactosylation but allowed α-L-fucosylation.
Department of Chemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Mickael
M
Guillemineau
France-Isabelle
FI
Auzanneau
D000117:Acetylglucosamine / Q000737:chemistry*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D005643:Fucose / Q000737:chemistry*; D005690:Galactose / Q000737:chemistry*; D006031:Glycosylation; D008956:Models, Chemical; D008969:Molecular Sequence Data; D013237:Stereoisomerism; D014312:Trisaccharides / Q000138:chemical synthesis* / Q000737:chemistry
D014312:Trisaccharides; D005643:Fucose; D000117:Acetylglucosamine; D005690:Galactose