FAST-ATOM-BOMBARDMENT MASS-SPECTROMETRY OF N-ACETYLATED NEOGLYCOLIPIDS OF THE 1-DEOXY-1-PHOSPHATIDYLETHANOLAMINO-LACTITOL-TYPE

N-Acetylated neoglycolipids (neoGL) of the 1-deoxy-1-phosphatidylethan olamino-lactiol-type (Lac-PtdEtn) carrying lactose, sialyllactose, dis ialyllactose, II(3)sialylgangliotetraose, II3,IV(3)disialylgangliotetr aose, lacto-N-tetraose, IV(6)sialyllacto-N-tetraose, lacto-N-triaose, and bloodgroup A determinant as carbohydrate moieties were synthesized either chemically or enzymatically by glycosylation or deglycosylatio n of the parent compounds. The neoGL were then analyzed by fast atom b ombardment mass spectrometry (FAB MS) with positive (FAB(+)) and negat ive ion (FAB(-)) detection. The resulting spectra showed intense pseud omolecular ions and characteristic fragmentations. FAB(-) spectra of t he N-acetylated Lac-PtdEtn-type neoGL showed pseudomolecular ions (M - H)(-) of one magnitude higher intensity compared to those from the co rresponding non-acetylated compounds. The main fragment ions were obta ined from successive cleavage of the sugar units, thereby indicating t he monosaccharide sequence. In FAB(+) spectra of the title compounds c learly detectable pseudomolecular ions were observed. The most promine nt peaks, however, were obtained from cleavage of phosphatidic acid. T he N-acetyl-ethyleneamine moieties of the corresponding glycosyl-Etn-f ragments most probably formed five membered rings and thereby mesomery -stabilized cations. Secondary ions resulting from loss of the respect ive terminal sugars demonstrated the monosaccharide sequence.