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Abstract

Nuclear magnetic resonance (NMR) is a nondestructive method capable of furnishing many-sided structural information; it is therefore highly desirable fully to exploit its potential, aiming at complete structure determinations without resorting to data obtained by other methods. This chapter presents examples of such structure elucidation and discusses the prospects of proton NMR becoming a self-sufficient method in the field of structural research of glycosphingolipids. In this study spin decoupling difference spectroscopy is applied because it is reasonable balance between the measuring time invested and the spectral information obtained. In this way one can identify most of the signals of the sugar ring protons for several glycosphingolipids containing up to 10 sugar residues. Another successful approach is the use of the nuclear Overhauser effect. The second, decisive, part of the problem is to extract structural information from those data. This task is greatly facilitated if series of structurally related substances are available. The work on Forssman glycolipid and the pentasaccharide ceramide from rabbit erythrocytes with B-like blood group activity offers a good opportunity to illustrate the approach. The results obtained revealed regular changes of chemical shifts related to the structural features a-e listed in this chapter. These regularities are shown to be applicable to structure determination of a bifurcate ceramide decasaccharide and of a series of highly crowded fucose-containing glycosphingolipids of the Lewis blood-group system.