P-glycosidic link

Natural occurring 2,6-dideoxy oligosaccharides of the D-series are P-glycosidically linked, those of the L-series represent a-glycosides. The absolute configuration at the anomeric center, however, is similar in both cases. 

Enzyme Inhibition - 2-Acetamido-2-deoxy-D-glucopyranose, chitobiose and chitotriose were P-glycosidically linked to various exo-glycosidase inhibitors, and evaluated as chitinase inhibitors. Good inhibition was found for an JV-formyl-pyrrolidine analogue (transition state mimic) and epoxybutyl chitobioside (an irreversible inhibitor). ... 

The effects of the stereochemistry of the oligosaccharide head-groups on the physical properties of aqueous synthetic glycolipids, e.g., 1,3-di-O-dodecylgly-cerol P-glycosidically linked to cello- or malto-oligosaccharides at 0-2, have been studied. ... 

Table 3. H NMR chemical shift data, useful for discrimination between ol- and p-glycosidically linked sialic acids (Haverkamp et al 1978, 1982)...

Most nucleosides contain D-ribose or 2-deoxy-D-ribose linked to N-1 of a pyrimidine or to N-9 of a purine by a P-glycosidic bond whose syn conformers predominate. 

Acetonitrile is another participating solvent, which in many cases leads to the formation of an equatorially linked glycoside [125-131], It has been proposed that these reactions proceed via an a-nitrilium ion intermediate. It is not well understood why the nitrilium ion adopts an axial orientation however, spectroscopic studies support the proposed anomeric configuration [130,131], It is known that nucleophilic substitution of the a-nitrilium ion by an alcohol leads to P-glycosidic bonds and the best P-selectivities are obtained when reactive alcohols at low reaction temperatures are employed. Unfortunately, mannosides give poor anomeric selec-tivities under these conditions. 

As an example of the carbohydrate component of a glycoprotein, the structure of one of the oligosaccharide chains of immunoglobulin G (IgG see p.300) is shown here. The oligosaccharide has an N-glycosidic link to the amide group of an asparagine residue in the Fc part of the protein. Its function is not known. 

When a nucleic acid base is N-glycosidically linked to ribose or 2-deoxyribose (see p.38), it yields a nucleoside. The nucleoside adenosine (abbreviation A) is formed in this way from adenine and ribose, for example. The corresponding derivatives of the other bases are called guanosine (G), uridine (U), thymidine (T) and cytidine (C). When the sugar component is 2-deoxyribose, the product is a deoxyribonucleoside—e. g., 2 -deoxyadeno-... 

Glycosylation.1 When treated with 1, RS- or ArS-glycosides undergo glycosy-lation with primary and secondary hydroxyl groups of O-glycosides to give P-O-linked disaccarides. Acetonitrile is the only suitable solvent. 

---