Isolation and characterization of human liver hematoside.

Abstract

The monosialoganglioside hematoside (GM3) is an important precursor in the synthesis of the more complex gangliosides. To obtain large quantities of GM3 for use in ganglioside biosynthetic experiments, we have devised a column chromatographic procedure for the isolation and purification of GM3 from human liver. A total ganglioside mixture was obtained from a 550 g sample of normal human liver. Quantitative analysis by gas-liquid chromatography indicated about 66 microgram of lipid-bound N-acetylneuraminic acid per gram of fresh tissue. Hematoside appeared as double bands on thin-layer plates and represented 86.4% of the total sialic acid content. Additional ganglioside species, notably GD3, were also seen. Hematoside was separated from the other gangliosides by GM3 obtained was 120 mg, which represented a 90% recovery. Although the long-chain base and sugar compositions of the upper and lower GM3 fractions were similar, striking fatty acid differences were detected. The upper fraction contained predominantly unsubstituted fatty acids, while the lower fraction showed a preponderance of alpha-hydroxy fatty acids. The unsubstituted fatty acid and hydroxy fatty acid composition of the total GM3 fraction was calculated to be 56.9% and 43.1%, respectively.