8-O-METHYL-N-GLYCOLYLNEURAMINIC ACID AND N-ACETYLGALACTOSAMINE CONTAINING GANGLIOSIDES FROM STARFISH ASTERIAS-RATHBUNI

The structure of gangliosides isolated from the liver of starfish Aste rias rathbuni was established by chemical methods, mass spectrometry, and enzymic hydrolysis with a neuraminidase. The major ganglioside was found to be a disialoganglioside with two 8-O-methyl-N-glycolylneuram inic acid residues bound with an N-acetylgalactosamine residue: 8-O-Me -NeuGc alpha 2-3(8-O-Me-NeuGc alpha 2-6)GalNAc beta 1-3Gal beta 1-4Glc beta 1-Cer. Its lipid part contains unsubstituted higher fatty acids (mainly palmitic and stearic) and sphingosines (for the most part C-20 and C-22). The minor ganglioside fraction consists of two monosialoga ngliosides the carbohydrate chains of which differed only in the posit ion of the terminal 8-O-methyl-N-glycolylneuraminic acid residue in th e N-acetylgalactosamine moiety: 8-O-Me-NeuGc alpha 2-3GalNAc beta 1-3G al beta 1-4Glc beta 1-1Cer and 8-O-Me-NeuGc alpha 2-6GalNAc beta 1-3Ga l beta 1-4Glc beta 1-1Cer. The higher fatty acid composition of the mi nor gangliosides was determined too.