9-Fluorenylmethoxycarbonyl (Fmoc)-glycine coupling of saccharide beta-glycosylamines for the fractionation of oligosaccharides and the formation of neoglycoconjugates.
We have devised a new saccharide derivatization scheme to provide not only the temporary attachment of a chromophore for detecting and facilitating the chromatographic separation of carbohydrates, but also the intermediates for further derivatization to produce neoglycoconjugates. Several neutral unprotected saccharide beta-glycosylamines were formed by the direct condensation of the reducing saccharides with aqueous ammonium bicarbonate. The beta-glycosylamine derivatives of N-acetylglucosamine, di-N-acetylchitobiose, and asialo-, digalactosylated biantennary complex oligosaccharide were N-acylated separately with excess 9-fluorenylmethoxycarbonyl (Fmoc)-glycine. The Fmoc-glycinamido beta-derivatives of these unprotected saccharides were well separated by normal-phase high-performance liquid chromatography and detected by ultraviolet absorption. Similar derivatization and fractionation of a partial acid hydrolyzate of chitin were equally successful resulting in the separation of Fmoc-glycinamido derivatives of di-N-acetylchitobiose to hepta-N-acetylchitoheptaose in the hydrolyzate. The reversibility of the Fmoc derivatization was demonstrated by treating the Fmoc-glycinamido derivative of N-acetylglucosamine with piperidine to generate its 1-N-glycyl-beta-saccharide derivative. The structure and stereochemistry of this product was confirmed by proton nuclear magnetic resonance spectroscopy. The 1-N-glycyl-beta-saccharide derivatives are stable intermediates for the formation of asparagine-linked neoglycoconjugates.
Arsequell
G
G
Department of Biochemistry, University of Oxford, United Kingdom.
Dwek
R A
RA
Wong
S Y
SY
D000117:Acetylglucosamine; D005449:Fluorenes / Q000737:chemistry*; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry; D006001:Glycoconjugates / Q000378:metabolism*; D009844:Oligosaccharides / Q000032:analysis* / Q000737:chemistry
D005449:Fluorenes; D006001:Glycoconjugates; D009844:Oligosaccharides; C080486:N-(9H-(fluoren-9-ylmethoxy)carbonyl)glycine; D005998:Glycine; D000117:Acetylglucosamine