Mass spectrometric analysis of permethylated glycosphingolipids II. Comparative studies on different blood-group active and related erythrocyte membrane glycosphingolipids |
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Authors: | Peter Hanfland Heinz Egge |
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Institution: | Institut für Experimentelle Hämatologie und Bluttransfusionswesen and Institut für Physiologische Chemie, University of Bonn, Germany |
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Abstract: | Three isomeric ceramide tetrasaccharides — P blood-group active globoside, lacto-N-neotetraosyl ceramide as ABH blood-group precursor, both isolated from human erythrocytes and “asiologanglioside” from human brain as reference standard — and two ceramide pentasaccharides — H blood-group active glycosphingolipid, obtained from blood-group B active ceramide hexasaccharide of human B erythrocytes after α-galactosidase treatment and ceramide pentasaccharide from rabbit erythrocytes with B-like blood-group activity — were investigated by mass spectrometry after permethylation. The carbohydrate moiety exhibits differences not only concerning the sugar sequence but also with regard to the position of some glycosidie linkages: Oligosaccharides containing N-acetylhexosamine substituted at position 4 produce spectra that are distinctly different from those containing C-3 substituted N-acetylhexosamines, thus allowing the differentiation between type 1 and type 2 carbohydrate chains. Moreover, oligosaccharide ions with a hexose at the cleavage site exhibit a fragmentation pattern different from those with a N-acetylhexosamine at the “reducing terminal”. The intensity ratio between parent ion and parent ion — 32 mass units is Q ? 3 in the first case, whereas in the latter case Q is <1. The Q-values are given for 14 oligosaccharide ions. Differences in the composition of the ceramide residues can also be deduced from the mass spectra. |
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Keywords: | TLC thin layer chromatography GC-MS gas chromatography-mass spectrometry B-I blood-group B active ceramide hexasaccharide B-H blood-group B active ceramide octasaccharide H blood-group active ceramide pentasaccharide derived from B-I after α-galactosidase treatment “asialo ganglioside” ceramide tetrasaccharide derived from human brain ganglioside SEM secondary electron multiplier TC total ion current MID multiple ion detection |
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