Anomeric Structures of Globoside and Ceramide Trihexoside of Human Erythrocytes and Hamster Fibroblasts

Abstract

The terminal galactosyl residue of ceramide trihexoside of human erythrocytes and BHK fibroblasts and that of the ceramide trihexoside derived from of human erythrocytes were hydrolyzed and totally converted to ceramide lactoside by an α-galactosidase isolated from fig. The enzyme showed a strict substrate specificity for α-galactosides and was completely freed from β-galactosidase activity. With the sequential application of glycosidases, the carbohydrate sequence and anomeric linkages of glycosphingolipids have been simultaneously determined. The presence of α-anomeric (equatorial) proton in these glycolipids was supported by a doublet at δ 4.6 ppm (J = 2 Hz) in the nuclear magnetic resonance spectrum of a trimethylsilyl derivative and by an absorption at 850 cm-1 in the infrared spectra. From these results and the results of methylation study, the structures of ceramide trihexoside and of globoside were determined, respectively, galactopyranosyl-α-(1 → 4)-galactopyranosyl-β-(1 → 4)glucopyranosyl-(1 → 1)ceramide, and 2-acetamido-2-deoxy-galactopyranosyl-β-(1 → 3)galactopyranosyl-α-(1 → 4)galactopyranosyl-β-(1 → 4)glucopyranosyl(1 → 1)ceramide.