Fractionation of Glycolipids and General Structural Approaches

Isolation and Fractionation of Glycolipids And General Structural Approaches 

Plasma-desorption mass spectrometry is another technique that has been applied successfully to the detection of readily removable fatty acyl substituents in intact glycolipids and their acylated derivatives. The specific location of the fatty acyl substituents in the ring of the glycosyl residues, as in LOS antigens, is determined by methylation under nonbasic conditions (see Section II.lb), followed successively by O-deacylation, ethylation of the exposed hydroxyl groups, and GC-MS analysis of partially alkylated alditol acetates21 ethyl groups denote the sites of previous O-acylation. 

At the outset of an examination of an oligosaccharide, a well resolved one-dimensional (ID) NMR spectrum provides a guide to anomeric configuration, and may also reveal unsuspected features, such as noncarbohydrate substituents. As an example (Fig. 1), the H-NMR spectrum of the oligoglycosylalditol from M. avium serovar 25 shows characteristic anomeric protons, especially for the j3-gluco configuration of the penultimate glucosyluronic residue.14 

An example of the use of NMR in the examination of intact glycolipids has been reported for one of the serine-containing GPLs from M. xenopi. Riviere and Puzo28 

The first evidence for the presence of species- and type-specific glycolipids within members of the Mycobacterium genus was generated by Smith and colleagues29-31 they proposed the term mycoside for type-specific glycolipids of 

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II. Isolation and Fractionation of Glycolipids and General Structural Approaches. 171... 

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