Glycolipid Analysis

Abstract

AbstractGlycolipids are conjugated macromolecules that have a carbohydrate (oligosaccharide) component covalently bound to a lipid (diacylglycerol, ceramide, sterol or polyprenol) component. They are present both in procaryotes and eucaryotes but the carbohydrate components, as well as the lipid components, vary considerably between different animal, plant and microbial cells. The biological specificity of a glycolipid is due mainly to the carbohydrate structure. The amphipathic nature of glycolipids means that a single extraction scheme is impractical for all the different molecular species while special techniques are required to differentiate between the neutral glycolipids and acidic glycolipids (gangliosides). Thin‐layer chromatography (TLC) and high‐performance liquid chromatography (HPLC) are the major purification methods. Chemical methods are used to determine the carbohydrate and lipid profiles as well as the linkage analysis of both types of components and are used in conjunction with gas chromatography (GC), HPLC and TLC, sometimes coupled with mass spectroscopy (MS). Enzymatic methods can be used to determine the linkage sequence and anomeric configurations of the oligosaccharide structures and the same parameters are being determined by immunological methods with increasing frequency. Enzymatic methods are also used to establish the linkage analysis of the fatty acid in the diacylglycerol species. However, various MS and both1H‐ and13C‐NMR (nuclear magnetic resonance) methods, but mostly the former, are now invariably used to confirm the full structural features of an unknown glycolipid. The type of MS method used, matrix‐assisted laser desorption/ionization (MALDI), fast atom bombardment (FAB) or tandem mass spectrometry (MS/MS) will depend on the type of glycolipid.