Oligosaccharides chains

Glycoproteins are proteins to which one or more oligosaccharide chains are covalently linked. 

Table 2. Symbols for monosaccharide residues and derivatives in oligosaccharide chains...

IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), Abbreviated terminology of oligosaccharide chains (Recommendations 1980), J. Biol. Chem., 257, 3347-3351 (1982) Eur. J. Biochem., 126,433-437 (1982) Pure Appl. Chem., 54,1517-1522... 

The first paper on the bioactive polysaccharides from Glycyrrhiza uralensis roots was published in 1996 by Kiyohara et al. [57]. They isolated a pectic type polymer with anti-complementary and mitogenic activity that was an acidic pectin, possibly containing rhamnogalacturonan type I as part of the total structure. Degradation of the uronic acid part of the molecule decreased both types of bio activities. The neutral oligosaccharide chains were shown to retain some of the activities of the native polymer, but it was suggested that they should be attached to the acidic core to retain maximum activity. 

Fig. I.—Hypothetical Transition State for the Cleavage of the Glycosidic Bond of a (GlcNAc) Chito-oligosaccharide Chain at Sub-Site D of the Substrate Binding Cleft of Lysozyme (from Ref. 65, with Permission).

Figure 41-7. The fluid mosaic model of membrane structure. The membrane consists of a bimolecu-lar lipid layer with proteins inserted in it or bound to either surface. Integral membrane proteins are firmly embedded in the lipid layers. Some of these proteins completely span the bilayer and are called transmembrane proteins, while others are embedded in either the outer or inner leaflet of the lipid bilayer. Loosely bound to the outer or inner surface of the membrane are the peripheral proteins. Many of the proteins and lipids have externally exposed oligosaccharide chains. (Reproduced, with permission, from Junqueira LC, Carneiro J Basic Histology. Text Atlas, 10th ed. McGraw-Hill, 2003.)...

Metastasis Abnormalities in the oligosaccharide chains of membrane glycoproteins and glycolipids are thought to be of importance... 

Many studies have been conducted in an attempt to define the precise roles oligosaccharide chains play in the functions of glycoproteins. Table 47-2 summarizes results from such studies. Some of the functions listed... 

Numerous lectins have been purified and are commercially available three plant lectins that have been widely used experimentally are listed in Table 47-7. Among many uses, lectins have been employed to purify specific glycoproteins, as tools for probing the glycoprotein profiles of cell surfaces, and as reagents for generating mutant cells deficient in certain enzymes involved in the biosynthesis of oligosaccharide chains. 

Based on the nature of the linkage between their polypeptide chains and their oligosaccharide chains, glycoproteins can be divided into three major classes (Figure 47-1) (1) those containing an O-glycosidic linkage (ie,... 

The process of N-glycosylation can be broken down into two stages (1) assembly of Dol-P-P-oligosaccha-ride and transfer of the oligosaccharide and (2) processing of the oligosaccharide chain. 

Previous enzyme Certain glycosyltransferases will only act on an oligosaccharide chain If It has already been acted upon by another processing enzyme. ... 

Protein conformation Differences in conformation of different proteins may facilitate or hinder access of processing enzymes to identical oligosaccharide chains. 

Isoelectric focusing of transferrin is a useful biochemical test for assisting in the diagnosis of these conditions truncation of the oligosaccharide chains of this protein alters its isolectric focusing pattern... 

The structures of many oligosaccharide chains can be elucidated by gas-liquid chromatography, mass spectrometry, and high-resolution NMR spectrometry. Glycosidases hydrolyze specific linkages in oligosaccharides and are used to explore both the structures and functions of glycoproteins. 

Appropriate nucleotide sugars and highly specific Golgi-located glycosyltransferases are employed to synthesize the oligosaccharide chains of GAGs. The one enzyme, one linkage relationship appears to hold here,... 

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