Ceramide structure of sphingomyelin from human milk fat globule membrane.

Sphingomyelin was purified from human milk fat globule membrane and submitted to phospholipase C to yield ceramide. The structure of this ceramide was investigated by gas liquid chromatographic analyses of its components, fatty acids and sphingoid bases. The structure of the native ceramide was confirmed by direct-inlet mass spectrometry. It was shown to contain a major base C18-sphingosine associated with a high proportion (60%) of C20, C22, C24 and C24:1 nonhydroxylated fatty acids. As these very long-chain fatty acids might be of nutritive importance, the concentration of sphingomyelin in human mild and its distribution in cream and skim milk were established.