Carbohydrates cyclic oligosaccharides

The present Recommendations deal with the acyclic and cyclic forms of monosaccharides and their simple derivatives, as well as with the nomenclature of oligosaccharides and polysaccharides. They are additional to the Definitive Rules for the Nomenclature of Organic Chemistry [13,14] and are intended to govern those aspects of the nomenclature of carbohydrates not covered by those rules. 

Derivatives play an essential part in almost all f.a.b.-m.s. studies of carbohydrates. They facilitate spectral interpretation (see Sections IV-VI), improve sensitivity (see Section 11,6), permit the analysis of salty samples (see later), allow unambiguous sequencing (see Section V,2), confirm the presence of cyclic structures (see Section VI,S), enable spectra to be obtained from very large molecules (see Section III,4), and help in the location of O-acylated residues in oligosaccharides (see Section V,S). 

A different strategy for the development of carbohydrate mimics has focused on the replacement of the non-pharmacophoric parts of active oligosaccharides by conformationally stable cyclic diols. Thus, looking for an analogue of the a-o-Man/)-(l — 2)-a-D-Man/>-(l — 6)-a-D-Man/)-mannotrioside, one of the terminal arms of the MangGlcNAc2... 

Compounds 1-10. c-x " c-x represent 05 and Cl of cyclic and acyclic carbohydrate, respectively, in which the carbohydrate moiety may be any mono or oligosaccharide, a or ano-mer (cyclic forms) C Hjn+, is a saturated aliphatic chain, while alkyl maybe either a saturated or an unsaturated aliphatic chain... 

Sugars are the simplest form of carbohydrates, and sugars such as monosaccharides, oligosaccharides, acyclic polyhydroxy alcohols, and cyclic sugar alcohols are well-known sweeteners. Shallenberger56 has written a good review on the structure-sweetness relationship of sugars. 

The interpretation of the mass spectra of oligosaccharide derivatives follows the general principles that have been elaborated for simple cyclic and acyclic carbohydrates (66MI1 74MI1). 

Methylated alditol units in oligosaccharides are cleaved in a manner similar to that described previously for partially methylated alditol acetates. On the other hand, substituted cyclic carbohydrates undergo a variety of types of fragmentation, the most important of which are summarized in Fig. 4 for simple permethylated glycosides. 

A variety of spectroscopies have been employed in a study of the electron transfer photophysics of 5-(l-carboxypyrenyl)- and 5-(l-pyrenyl)-2 -deoxyuridine. The inclusion complexes of a-, P- and y-CDs and 2,6-di-O-methyl and 2,3.6-tri-O-methyl P-CD have been investigated using UV (as well as NMR) spectroscopy. The electrochemical oxidation of 4-0-glucopyranosyl-D-glucose in the presence of bromide ions has been examined using cyclic chronovoltammetry. Un-derivatized oligosaccharides and other carbohydrate types were analysed by semimicrocolumn LC/pulsed amperometric detection. ... 

The commercial manufacture and modification of oligosaccharides are important features of several industries. The processes are usually hydrolytic but in a few instances enzymes catalyse a transglycosylation onto another carbohydrate rather than onto water, thus creating a new polymer. /S-Cyclodextrin (48), which is a macrocyclic structure comprising seven molecules of glucose all linked l-4o, is synthesized from starch with an enzyme from Bacillus species (Scheme 6.27). This cyclic carbohydrate acts... 

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