Carbohydrates, complex types

H. Lonn, Synthesis of a tetra- and a nonasaccharide which contain a-L-fucopyranosyl groups and are part of the complex type of carbohydrate moiety of glycoproteins, Carbohydr. Res. 739 115 (1985). 

Another type of carbohydrate complex is the cyclic ester formed between a glycitol and a polyanion such as borate or molybdate (4). The possible species present at equilibrium have not previously been evaluated by iteration. The system mannitol-borate has been so analyzed, and it was possible to use the same approach as that for the metal chelates. 

During the extraction process three types of interactions are usually disrupted, these are van der Waals forces in lipid-lipid, lipid-protein, and liquid-carbohydrate complexes electrostatic and hydrogen bonding interactions between lipids andproteins andcovalent bonding between lipids, carbohydrates, and proteins (Roby t and White, 1987). The solvent of choice depends on the type of lipid and the interactions to be disrupted. Thus, neutral lipids may be extracted with nonpolar solvents, while phospholipids and glycolipids are extracted with more polar solvent mixtures (Shahidi and Wanasundara, 1998). 

Fig. 1. The GP Ib-IX-V complex. The complex consists of seven transmembrane polypeptides denoted GP Iba (mol wt 145,000), GP Ibp (mol wt 24,000), GPIX (mol wt 17,000) and GP V (mol wt 82,000), in a stoichiometry of 2 2 2 1. The hatched region represents the plasma membrane. The area above the hatched region represents the extracellular space that below represents the cytoplasm. The complex is a major attachment site between the plasma membrane and the cytoskeleton. Two molecules associated with the cytoplasmic domain are depicted a 14-3-3 dimer, which may mediate intracellular signaling, and actin-binding protein, which connects the complex to the cortical cytoskeleton and fixes its position and influences its function. The dark circles represent O-lihked carbohydrate and the dark squares represent IV-linked carbohydrate. Both types of carbohydrate are added after...

Although a monoclonal antibody is considered to consist of a single molecule, in reality this is not the most frequent case. Due to posttranslatorial modification, especially glycosylation,12,13 a family of molecules with identical aminoacid backbone, but different carbohydrate composition, is generated.14,15 The possible structure of N-linked oligosaccharides of the complex types is shown in Fig. 3. 

Haneda K, Inazu T, Yamamoto K, Kumagai H, Nakahara Y, Ko-bata A. Transglycosylation of intact sialo complex-type oUgosac-charides to the N-acetylglucosamine moieties of glycopeptides by Mucor hiemalis endo-beta-N-acetylglucosaminidase. Carbohydr Res. 1996 292 61-70. 

FIGURE 15.1 Three examples of A-linked carbohydrate chains found on glycoproteins oligomannose type (1), A-acetyllactosamine type (or complex type, 2) and hybrid type (3). The common pentasaccharide core is indicated. 

Ogawa, T, Sugimoto, M, Kitajima, T, Sadozai, K K, Nukada, T, Synthetic studies on cell surface glycans. 51. Total synthesis of an undecasaccharide. A t)fpical carbohydrate sequence for the complex type of glycan chains of a glycoprotein. Tetrahedron Lett., 27, 5739-5742, 1986. 

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