Characterization and quantitative determination of gangliosides and neutral glycosphingolipids in human liver.

The neutral and acidic glycolipids from the liver of an 11-year-old male were quantitatively isolated and characterized. The total concentration of gangliosides was also determined in sampled from five other human livers. Lipid-bound sialic acid varied between 190-248 nmol/g with a mean value of 212 nmol/g. The major ganglioside was GM3, which represented 91.6% of the sialic acid. Besides GM3 and GM1, a wide variety of other minor monosialogangliosides were isolated. Gangliosides of the gangliotetraose series with up to four sialic acids were demonstrated in human liver for the first time. The composition of the ceramide portion of the gangliotetraose gangliosides was considerably different from that of the "visceral" gangliosides, GM3, GD3, and LM1 (sialosyl-lactoneotetraosylceramide), which suggests that these two groups of gangliosides are biosynthesized in two different pools. The concentration of the neutral glycolipids was approximately the same as that of the gangliosides. Lactosylceramide was the largest fraction, closely followed by galactosylceramide, glucosylceramide, and globotriaosylceramide. The ceramide composition of the neutral glycolipids resembled that of the "visceral" gangliosides, suggesting that they are metabolically related. 2-Hydroxy fatty acids were found in glucosyl-, galactosyl-, and lactosylceramides as well as in ganglioside GM3.