N-glycosidic link

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. 

On the cell surface of certain glycoproteins, O-glycosidic links are found between the carbohydrate part and a serine or threonine residue, instead of N-glycosidic links to asparagine residues. This type of link is less common than the N-glycosidic one. 

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-... 

J. Montreuil and J. F. C. Vliegenthart, Primary Structure and Conformation of Glycans N-Glycosidically Linked to Peptidic Chains, Proc. Int. Siimp. Glycoconjugates, 4th, Woods Hole, 1977, Academic Press, New York, 1979, pp. 35-78. 

Glycoproteins are glycosides that have a protein aglycone. The protein is usually linked to a polysacharide (See section 1.4.4) by an O or N glycosidic link. Glycoproteins are found in all forms of life. They exhibit a wide range of biological activities. For example, they may act as receptors, hormones and enzymes. 

The bases found in RNA (ribonucleic acid) are the purine heterocyclics adenine (6-aminopurine) and guanine (2-amino-6-oxypurine) and their complementary pyrimidine bases uracil (2,4-dioxypyrimidine) and cytosine (2-oxy-4-aminopyrimidine), respectively (Section 1, Appendix). In RNA double-stranded duplexes adenine (A) base-pairs with uracil (U) via two hydrogen bonds (A=U) and guanine base-pairs with cytosine (C) via 3 hydrogen bonds (G=C). Adenine forms the nucleoside adenosine by an N-glycosidic link with the... 

N-Glycosidically linked oligosaccharides. The oligomannosidic type is rich in mannose residues, whereas the complex type contains carbohydrate residues in the outer domain. Both types have a common core. 

UDP-7V-acetylglucosamine (uridine diphosphate), nikkomycins act as potent competitive inhibitors of chitin synthase and exhibit potent fungicidal, insecticidal, and acaricidal activities [320]. Nikkomycin X and Z, isolated as major components, contain the hydroxypyridylhomothreonine (HPHT) moiety, the aminohexuronic acid, and a nucleoside moiety N-glycosidically linked to 4-formyl-imidazolin-2-one or a uracil base, respectively [321, 322]. 

Suzuki S, Kazuaki K, and Susumu H (1992) Two-dimensional mapping of N-glycosidically linked asialo-oligosaccharides from glycoproteins as reductively pyridylaminated derivatives using dual separation modes of high-performance capillary electrophoresis. Analytical Biochemistry 205(2) 227-236. 

The presence of both O- and N-glycosidically linked oligosaccharides containing sialic acid was shown in proteoglycans from swarm rat chondrosarcoma and chick limb bud chondrocyte cultures by Lohmander et al. (1980) and De Luca et al. (1980). The 0-glycosidically linked chains were all related to the sialylated T-antigen structure (Lohmander et al. 1980). 

Sialyltransferases with N-Glycosidically Linked Oligosaccharide Substrates... 

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