| Summary: | 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 Ggal 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.
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