Journal of Lipid Research, Vol. 9, 366-370, May 1968
Copyright © 1968 by Lipid Research, Inc.

Lipid components of sialosylgalactosylceramide of human brain

Badruddin Siddiqui and R. H. McCluer

Departments of Physiological Chemistry and Psychiatry, The Ohio State University, Columbus, Ohio 43210

A ganglioside, previously designated HG-B in our laboratory, was isolated from mixed human brain ganglioside preparations and shown to contain equimolar quantities of sialic acid, galactose, and sphingosine. Treatment of this material with neuraminidase yielded a galactosylceramide. The ganglioside, now referred to as sialosylgalactosylceramide, thus appears to be identical with G_gal reported by Kuhn and Wiegandt. The fatty acids and long-chain bases of this material were analyzed by gas-liquid chromatography. Approximately equal amounts of normal and hydroxy acids were found. Oleic, palmitic, and stearic acids were the only normal fatty acids present. In the hydroxy series, the C₂₄ and C₂₃ saturated acids were the major components. The ratio of C₂₀ to C₁₈ long-chain base was approximately 5:3.

These data suggest that sialosylgalactosylceramide has no direct metabolic relationship with either the major brain gangliosides or adult brain cerebroside.

Supplementary key words sialosylgalactosylceramide • ganglioside • cerebroside • hydroxy fatty acids • normal fatty acids • sphingosine • sialic acid • thin-layer chromatography • gas-liquid chromatography • di(2-ethylhexyl) phthalate • trimethylsilyl ether derivatives

Submitted on October 11, 1967
Accepted on January 22, 1968

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