Identification of a novel heptaglycosylceramide with two fucose residues and a terminal hexosamine

Abstract A polar fucose-containing glycosphingolipid fraction isolated from dog small intestine has been characterized by mass spectrometry of intact methylated, and methylated and reduced (LiAlH 4 ) glycolipid. The native fraction, which was homogenous on thin-layer chromatography, was shown after methylation to be a mixture of two compounds. One was identified as a hexaglycosylceramide with the following composition and sequence: fucose-hexose-[fucose]-hexosamine-hexose-hexose-ceramide, with a terminal saccharide structure similar to blood group Le b determinants. The second compound was a novel heptaglycosylceramide with the sequence: hexosamine-[fucose]-hexose-[fucose]-hexosamine-hexose-hexose-ceramide. This glycolipid was also detected in human small intestine and pancreas. The dog intestinal fraction had phytosphingosine as its major base and contained almost exclusively 2-hydroxy fatty acids (16: 0–24: 0). The fraction of human pancreas differed in having sphingosine as its major base and normal fatty acids (16: 0–24: 0) as major acids.