Immunochemistry of I/i-active oligo- and polyglycosylceramides from rabbit erythrocyte membranes. Determination of branching patterns of a ceramide pentadecasaccharide by 1H nuclear magnetic resonance.
1H NMR spectra of the ceramide hexasaccharide obtained after the removal of the terminal alpha-Gal and subterminal beta-Gal residues from the ceramide decasaccharide, Gal(alpha 1-3)Gal(beta 1-4)GlcNAc(beta 1-3)[Gal(alpha 1-3)Gal(beta 1-4)GlcNAc (beta 1-6)]Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)Glc(beta 1-1)Cer, showed that terminal and internal GlcNAc residues are differentiated by their chemical shifts. This finding enabled us to determine the primary structure of the title compound as Gal(alpha 1-3)Gal(beta 1-4)GlcNAc (beta 1-3)[Gal(alpha 1-3)Gal(beta 1-4)GlcNAc(beta 1-6)]Gal(beta 1-4)GlcNAc (beta 1-3)[Gal(alpha 1-3)Gal(beta 1-4)GlcNAc(beta 1-6)]Gal(beta 1-4)GlcNAc (beta 1-3)Gal(beta 1-4)Glc(beta 1-1)Cer. Alternative branching of this oligosaccharide chain was excluded since the removal of all terminal alpha-Gal and penultimate beta-Gal residues yielded a ceramide nonasaccharide containing one terminal and two internal 1----3-linked GlcNAc residues, as well as two terminal 1----6-linked GlcNAc units. The intermediate degradation products of the ceramide deca- and pentadecasaccharides , viz. the ceramide octa- and dodecasaccharide , obtained by the removal of alpha-Gal residues only, as well as the linear ceramide heptasaccharide, Gal(alpha 1-3)Gal(beta 1-4)GlcNAc(beta 1-3) Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)Glc(beta 1-1)Cer, and ceramide hexasaccharide, Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)GlcNAc (beta 1-3)Gal(beta 1-4)Glc(beta 1-1)Cer, were also investigated. The usefulness of the glycosylation-induced chemical shifts is discussed.
D000818:Animals; D002240:Carbohydrate Sequence; D002554:Cerebrosides / Q000032:analysis*; D004910:Erythrocyte Membrane / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D011817:Rabbits
D002554:Cerebrosides