Glycoconjugate

Glycoconjugates. Another class of carbohydrates are the glycoconjugates (14), composed of glycoproteins, proteoglycans, peptidoglycans, and glycohpids. 

Glycoconjugate (Section 25.6) A biological molecule in which a carbohydrate is linked through a glycoside bond to a lipid or protein. 

Glycoconjugate, 991 Glycogen, function of, 1001 structure of, 1001 Glycol, 234, 662 Glycolic acid, pKa of, 756 structure of, 753 Glycolipid, 991... 

Goldstein DB, Hungund BL, Lyon RC Increased surface glycoconjugates of synaptic membranes in mice during chronic ethanol treatment. Br J Pharmacol 78 8-10, 1983... 

Three 3-deoxynonulosonic acids containing amino groups are known. The most abundant of these is 5-amino-3,5-deoxy-D- /yc ro-D-ga/acto-nonulosonic acid (neuraminic acid, 27), which occurs in different extracellular polysaccharides. Some of these, like colominic acid from E. coli K1, are homopolysaccharides. Neuraminic acid is generally A-acetylated and, as in the animal glycoconjugates, has only been found in the a-pyranosyl form (27). It also occurs in some LPS, for example those from some Rhodobacter... 

Other disorders in which glycoproteins have been implicated include hepatitis B and C, Creutzfeldt-Jakob disease, and diarrheas due to a number of bacterial enterotoxins. It is hoped that basic smdies of glycoproteins and other glycoconjugates (ie, the field of glycobiology) will lead to effective treatments for diseases in which these molecules are involved. Already, at least two disorders have been found to respond to oral supplements of sugars. 

In the author s laboratory, it has never been found necessary to resort to matrices other than glycerol or 1-thioglycerol for the analysis of saccharides and glycoconjugates. Nevertheless, alternative matrices are often equally effective, and, in some laboratories, they are preferred. The most widely used include tetraethyleneglycol (4) and its higher-molecular-weight relatives, the poly(ethyleneglycol)s, and such basic matrices as N,N -bis(2-aminoethyl)ethylenediamine ( triethylenetetramine, 5), 2,2 -... 

The synthesis of glycoconjugates opens the route to one of the most important class of biomolecules which play an active role in relevant biological reactions [26]. One way to do so is to use enzymes, which, however, suffer from instability and slow reaction rates. 

Dondoni, A. Massi, A. (2006) Design and Synthesis of New Classes of Heterocyclic C-Glycoconjugates and Carbon-Linked Sugar and Heterocyclic Amino Acids by Asymmetric Multicomponent Reactions (AMCRs). Accounts of Chemical Research, 39, 451M63. 

Franceschini V., Lazzari M. and Ciani F. (1996). Identification of surface glycoconjugates in the olfactory system of turtle. Brain Res 725, 81-87. 

Takami S., Getchell M. and Getchell T. (1995). Resolution of sensory and mucoid glycoconjugates with terminal O-galactose residues in the mucomicrovillar complex of the vomeronasal sensory epithelium by dual confocal laser-scanning microscopy. Cell Tiss Res 280, 211-216. 

Tobet S.A., Crandall J. and Schwarting G. (1992). Relationship of migrating LHRH neurons to unique olfactory system glycoconjugates in embryonic rats. Dev Biol 155, 471-482. 

Stefansson, M. and Westerlund, D., Ion-pair LC of carbohydrates at alkaline pH. Separation and retention behavior of glycoconjugates, Chromatographia, 35, 55, 1993. 

---