Negative ion fast atom bombardment mass spectrometry of gangliosides and asialo gangliosides: a useful method for the structural elucidation of gangliosides and related neutral glycosphingolipids.

Structural elucidation, including molecular weight, carbohydrate sequence and molecular species of the ceramide portion, of gangliosides and asialo gangliosides from bovine brain, was successfully performed by negative ion fast atom bombardment mass spectrometry (NEG-FAB-MS). Ceramide monohexoside, ceramide dihexoside, asialo GM2 (GA2) and asialo GM1 (GA1), all of which were prepared from bovine brain gangliosides by treatment with 1 M formic acid and monosialogangliosides, GM3, GM2, and GM1, were analyzed without any derivatization by NEG-FAB-MS. They clearly gave the intensive molecular ion species, (M-H)-, and the fragment ions cleaved at glycosidic linkage sequentially from the non-reducing end with or without the ceramide portion. The spectra were quite simple, easily obtained without expansion of ion intensity, and extremely useful for the structural elucidation of underivatized glycosphingolipids.