Oligosaccharides, structural characteristics

The use of primary fragment ions is not enough to allow for extensive structural characterization. Careful examination, however, of the secondary fragmentation pathways provides a more precise means to identify some, but not all, of the structural characteristics for the substance under study. Aspinall (82MI7) reviewed a useful example in which the permethylated alditols from the milk oligosaccharides lacto-N-tetraose [Gai- (1 3)-Glc- l 3)-Gal-... 

This book is designed to be useful to a broad array of researchers who might find oligosaccharide biopolymers of interest As such, it must cover biochemistry and enzymology as well as those unique structural characteristics that require novel analytical tools. New aspects of usefulness must also be addressed Consequently, the book has three basic parts ... 

Structural characteristics of xylo-oligosaccharides present in brewery s spent grain and Eucalyptus wood hydrolysates... 

These carbohydrate derivatives, including the oligosaccharides, are intriguing potential structures for cationic systems and ultimately ionic liquids owing not only to their particular structural characteristics, but also to their ready availability for large scale production. 

Several mono-carba-oligosaccharidic alpha amylase inhibitors, such as acarbose and its homologs, amylostatins, trestatins, oligostatins, adipo-sins, and so on, have been isolated from cultures of micro-organisms, and considerable interest in the biochemistry and chemistry of this class of inhibitors has been stimulated. The characteristic core-structure for inhibitory action is composed of a trihydroxy(hydroxymethyl)cyclohexene moiety and a 4-amino-4,6-dideoxy-D-glucopyranose moiety, bonded by way of an imino linkage at the allylic position. A similar structural unit has been found in the antibiotic validamycins. 

In addition to well-resolved one-dimensional (ID) 1H and 13C spectra, which are usually sufficient for monitoring synthetic steps, HR-MAS techniques can be applied to two-dimensional (2D) homonuclear and heteronuclear experiments, which allow a wealth of structural information to be obtained. H,13C HMQC (heteronuclear multiple quantum coherence) spectra are particularly useful in the analysis of solid support-bound oligosaccharides, since the anomeric protons exhibit characteristic resonances. Such a spectrum of a polymer-bound trisaccharide glycal is shown in Figure 8.4. 

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