A new chromatographic approach to the resolution of individual gangliosides. Ganglioside mapping

Abstract

1. Anion-exchange column chromatographies on DEAE-Sephadex, DEAE-Sepharose and QAE-Sephadex were tested for fractionation of ganglioside-molecular species. DEAE-Sepharose gave the best resolution, with good separation of mono-, di-, tri- and even tetrasialogangliosides. Even minor gangliosides could be resolved and detected by silica gel thin-layer chromatography of successive fractions of effluent from a DEAE-Sepharose column. In this two-step chromatographic system, the first step of elution from the column depends on differences in anionic charge and the second step of development on a silica gel plate depends on differences in polarity. With this ganglioside-mapping technique, at least 25 unidentified gangliosides were separated from bovine and human brains in addition to the well-known compounds, G7, GM3, GM2, GM1, GM1 (GlycNeu), GD2, GD3, GD1a, GD1a-GAN, GD1a(AcNeu, GlycNeu), GD1b, GT1a, GT1b and GQ. 2. The procedure was used to compare the gangliosides in human (3, 5 and 35 years old), bovine, cat, rat, rabbit, chicken and dog brains. The ganglioside profiles of human, cat, rat, rabbit and dog brains only differed in minor components. However, the gangliosides in chicken brain were unexpectedly complex, at least 30 minor gangliosides, including 15 monosialogangliosides being recognized. Gangliosides containing N-glycolylneuraminic acid (GDIa and GM1 type) were only found in bovine brain. The concentrations of tri- and tetrasialogangliosides in human brain were found to increase during maturation. 3. The long chain bases of each ganglioside fraction, in which the content of sialic acid was confirmed by measuring the ratio of sialic acid to stearic acid, were also analyzed as their aldehydes. The ratios of C-20 to C-18 sphingosine increased in the series from the mono- to tetrasialoganglioside fraction (0.216-1.777) in all animal brains tested.