Oligosaccharides sequencing

Early conformational studies by HOESY experiments are illustrated by the work of Batta and Kover54 who were able to access oligosaccharide sequencing and conformational distribution around the glycosidic bond in model compounds. These determinations make use of relayed proton-proton-carbon cross-relaxation. 

The Oligosaccharide Sequences of Blood-Group and Related Determinants Shown in Figs. 3 and 4... 

Fig. 3—Possible solution conformers of oligosaccharide sequences related to the Le and Leb antigens (Lea,Lex, sialyl Le", sialyl Lex, ALeb, ALey). As described in the text, oligosaccharides in solution sample 3D space in local energy-minima wells, so that the conformations shown are approximate only. The models stand only to show the stereochemical hindrance to movement in these branched oligosaccharides. The molecules are shown without the anomeric hydroxyl group. 

The oligosaccharide sequences just discussed are linked to glycoproteins through the following (generalized) N- and O-linked cores (to asparagine and serine or threonine, respectively). 

Interestingly, erythrocytes that had lost (2—>3)-sialyl residues were still agglutinable by influenza viruses.531 In similar experiments with Madin-Darby, bovine kidney-cells and Sendai viruses, (2— 3)-sialyl residues as components of the oligosaccharide sequence a-Neu5Ac-(2— 3)-/3-Gal-(T 3)-GalNAc constitute specific receptors for these... 

In bacterial lipopolysaccharides, O-specific chains composed of repeating, or modified repeating, units are linked to a unique oligosaccharide sequence of the core region which is connected to a lipid A fragment serving as a hydrophobic anchor embedded in the bacterial outer-membrane. Biosynthesis of O-specific chains was found to occur independently on formation of other structural fragments of the lipopolysaccharide molecule. Both block and monomeric mechanisms were demonstrated for the biosynthesis of these polymers. 

Fast atom bombardment mass spectrometry (FABMS) has become an important addition to the ionization techniques available to the analytical chemist in recent years. It has been particularly useful in a number of diverse applications which include molecular weight determinations at high mass, peptide and oligosaccharide sequencing, structural analysis of organic compounds, determination of salts and metal complexes, and the analysis of ionic species in aqueous solutions. This paper will focus on some aspects of the quantitative measurement of ionic species in solution. The reader is referred to a more comprehensive review for more details of some of the examples given here as well as other applications (1). 

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