| Popis: |
Methylation analysis of ceramide tetrasaccharide isolated from human erythrocytes gave acetates of 2,3,6-tri-O-methylgalactitol and 2,4,6-tri-O-methylgalactitol in a ratio of 1 : 1, and about 50% of the galactose was oxidized by periodate. Rat kidney ceramide tetrasaccharide gave, in contrast, a much larger proportion of the acetates of 2,4,6-tri-O-methylgalactitol (ratio 1 : 0.3), and less than 20% of the galactose was oxidized by periodate. Sequential degradation by β-N-acetylhexosaminidase, α-galactosidase, and β-galactosidase showed ceramide tetrasaccharides to have identical carbohydrate sequences and anomeric structures. The major part of ceramide trihexoside derived from rat kidney ceramide tetrasaccharide migrated on thin-layer chromatography more slowly than that derived from other ceramide tetrasaccharides. The structure of a major part of rat kidney ceramide tetrasaccharide was thus determined to be GalNAcβ(1→3)Galα(1→3)Galβ(1→4)Glcβ-(1→1)Cer, whereas other ceramide tetrasaccharides have Galα(1→4) structure at the penultimate residue. |
