13C-nuclear magnetic resonance of glycosphingolipids.

Spectra of 125 MHz 13C-nuclear magnetic resonance (NMR) of glycosphingolipids, GlcCer, GalCer, sulfatide, LacCer, and nLc4Cer have been studied, and the following results were obtained. (i) Signals of ring carbons of each sugar component are distributed in a wide field (50-110 ppm) and clearly separated. (ii) Chemical shifts of anomeric carbon (C1) and methylene carbon (C6) of sugars are far from those of other methine carbons of sugars and characteristic of sugar components, which makes it possible to identify each sugar component and its molar raito. (iii) The downfield shifts (about 6-9 ppm) of alpha-carbon signals involved in the glycosidic linkages and upfield shifts (about 1.5-2 ppm) of the neighboring beta-carbons, which are known as glycosylation shifts, could be observed. (iv) Characteristic shifts of aglycon signals caused by the presence of an OH group at the alpha-position of fatty acid were assigned. These observations are useful for the characterization of glycosphingolipid structures.