Structure determination of peracetylated glycosphingolipids by one‐ and two‐dimensional 1H NMR at 360 and 500 MHz

Abstract

AbstractThe analysis of two‐dimensional proton shift‐correlated 500 MHz NMR spectra of several peracetylated glycosphingolipids confirmed that peracetylated oligosaccharides are particularly well suited for the identification of the constituent sugar residues and the elucidation of the sites of glycosidic linkage. Although a number of partial sequences could be determined by inter‐residue nuclear Overhauser effect or long‐range scalar coupling across the glycosidic bonds, the full sequence determination of larger oligosaccharides has several limitations owing to experimental difficulties and possible ambiguities in assignments due to signal overlap. The following peracetylated glycosphingolipids were investigated by two‐dimensional methods at 500 MHz: Galα(1→4)Galβ(1→4)Glcβ(1→1)Cer (Cer = ceramide), GalNAcβ(1→3)Galα(1→4)Galβ(1→4)Glcβ(1→1) Cer (globoside) and Galα(1→3)Galβ(1→4)GlcNAcβ(1→3)Galα(1→3)Galβ(1→4)GlcNAcβ(1→6)Galβ(1→4)GlcNAcβ(1→3)Galβ(1→4)Glcβ(1→1)Cer. To compare the potential of one‐ and two‐dimensional methods, the spectra of peracetylated Galβ(1→4)Glcβ(1→1)Cer, Galβ(1→4)GlcNAcβ(1→3)Galβ(1→4)Glcβ(1→1)Cer. To compare the potential of one‐ and two‐dimentional methods, the spectra of peracetylted Galβ(1→4) Glcβ(1→1)Cer were assigned with the aid of spin‐decoupling difference spectroscopy at 360 MHz.