Isolation and Characterization of Major Urinary Oligosaccharides Excreted by a Patient with Type 3G_M1 Gangliosidosis

抄録

Two major oligosaccharides were isolated from the urine of a patient with type 3 G_M1 gangliosidosis. From structural studies including compositional sugar analysis, fast-atom bombardment mass spectrometry, direct-inlet chemical ionization mass spectrometry, methylation analysis, chromium trioxide oxidation, and proton magnetic resonance spectroscopy, their structures were deduced to be as follows:
oligosaccharide 1 Galβl→4GlcNAcβ1→2Manα1→3Manβ1→4GlcNAc
Galβ1→4GlcNAcβ1→2Manα1→6
Oligosaccharide 2 Galβ1→3GlcNAcβ1→3Galα1→4Glc
Fucα1→4 Fucα1→3
Both oligosaccharides have β-linked galactose at the non-reducing ends. Oligosaccharide 1 is one of the most common urinary oligosaccharides found in type 1 and type 2_Gm1, gangliosidosis. Oligosaccharide 2, lacto-N-difucohexaose II, has not been described in the urine of G_M1, gangliosidosis patients. Excretion of oligosaccharide 1 in the type 3 patient was much less than that of a type 2 patient. Thin-layer chromatographic analysis revealed that the excretion of oligosaccharides with higher molecular weight than that of oligosaccharide 1 (octasaccharide) in the type 3 patient was much less than that of a type 2 patient, raising the possibility that the mutant β-galactosidase of type 3 G_M1, gangliosidosis can still act to some extent on higher molecular weight oligosaccharides containing β-linked galactose at the non-reducing end.