| Summary: | Gangliosides were isolated from human, bovine, and rabbit plasma and were quantified by gas–liquid chromatography. Purification was achieved by sequential use of partitioning in solvents, DEAE-Sephadex chromatography, base treatment, and silicic acid chromatography. Human and bovine plasma yielded slightly more than 1 μmole of lipid-bound sialic acid/100 ml; for rabbit plasma the value was 0.28 μmole/100 ml. The total bovine plasma ganglioside fraction contained equal amounts of N-acetylneuraminic and N-glycolylneuraminic acids, rabbit plasma gangliosides had about 1% of the latter, and the human plasma sample contained only the former. Thin-layer chromatography revealed important differences among the plasmas from the three species, but all possessed hematosides and hexosamine-containing gangliosides. The approximate ratios of these two categories, based on sialic acid content, were (hematosides:hexosamine-type):human, 2:1; rabbit, 3:2; and bovine, 2:3. The fatty acid compositions of both categories were characteristic of extraneural gangliosides and included six major acids:palmitic, stearic, behenic, tricosanoic, lignoceric, and nervonic. The major long-chain base in each sample was sphingosine, while only a trace of the C20 isomer was detected.
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