Fatty acid and long‐chain base composition of gangliosides isolated from adult human brain

A series of major and minor ganglioside species were isolated from a single human adult brain and analyzed for their lipophlic composition. Hematosides, G_M3 and G_D3, each showing double bands on thin‐layer chromatograms, were separated into the upper band and lower band fractions to be analyzed for the heterogeneity of their ceramide moieties. The upper band fractions of G_M3 and G_D3 were found to contain relatively high amounts of longer‐chain fatty acids (C₂₀C₂₆), whereas the lower band fractions contained high amounts of shorterchain fatty acids (C₁₆C₁₈). Compared to other gangliosides which contain hexosamine, the two hematosides contained a smaller proportion of stearic acid. The proportion of 4‐eicosasphingenine was found to increase with increasing sialic acid content in gangliosides. These findings suggest that, in the biosynthesis of various gangliosides, N‐acetylhexosamine is preferentially transferred to hematosides rich in stearic acid, and sialic acid residues are preferentially transfered to 4‐eicosasphingenine‐containing species.