W-Acetylglucosamine

Shlesinger, P.H., Doebber, T.W., Mandell, B.F., White, R., DeSchryver, C., Rodman, J.S., Miller, M.J. and Stahl, P.D. (1978) Plasma clearance of glycoproteins with terminal mannose and W-acetylglucosamine by liver non-parenchymal cells. Study with betaglucuronidase, N-acetyl-beta-D-glucosamine, ribonuclease B and agalacto-orosomucoid.Biochem. J., 176, 103-108. 

Fucomucins (Blix, Werner) protein, L-fucose, W-acetylglucosamine, N-acetylgalactosamine, D-galactose... 

Methylglucose 3- 0-Methyl-W-acetylglucosamine /V-Acetylglucosamine-6-sulfate Gulose... 

Fig. 6. Principle of the poly-iV-acetyllactosamine labelling method. In the first step, cells are treated with endo-fl-galacto-sidase, which cleaves only poly-iV-acetyllactosamine glycans. In the second step, the terminal W-acetylglucosamine residues are labelled by the transfer of radiolabelled galactose from UDP-galactose with the aid of galactosyltransferase [40,41],...

Addition of sialic acids (Sia) by STs, fucose by FUTs, galactose (Gal) by Gal-Ts, W-acetylglucosamine (GIcNAc) by Mgats, and suLfuric acids by Sph- T to generate di-, tri- and tetra-antennary oligosaccharides... 

Scheme 5 Derived structure of 0-polysaccharide from Salmonella riogrande 0 40. GalNAc, W-acetylgalactosamine Man, mannose Glc, glucose GIcNAc, W-acetylglucosamine.

W-acetylmuramic acid O W-acetylglucosamine Tetrapeptide amino acid O Interbridge amino acid... 

Chitin is a linear homopolysaccharide composed of W-acetylglucosamine residues in /3 linkage (Fig. 7-18). The only chemical difference from cellulose is the replacement of the hydroxyl group at C-2 with an acety-lated amino group. Chitin forms extended fibers similar to those of cellulose, and like cellulose cannot be digested by vertebrates. Chitin is the principal component of the hard exoskeletons of nearly a million species of arthropods—insects, lobsters, and crabs, for example— and is probably the second most abundant polysaccharide, next to cellulose, in nature. 

D-Glucosamine can be obtained by hydrolysis of chitin, a polysaccharide found in the shells of lobsters and crabs and in the external skeletons of insects and spiders. The amino group of D-glucosamine as it occurs in chitin, however, is acetylated thus, the repeating unit is actually W-acetylglucosamine (Fig. 22.18). The glycosidic linkages in chitin are jS(l 4). X-Ray analysis indicates that the structure of chitin is similar to that of cellulose. 

Fig.2. Glycosaminoglycans (mucopolysaccharides) and sites of attack by degradative enzymes. Absence or defective function of any one of these enzymes leads to accumulation of incompletely degraded mucopolysaccharide, i.e. mucopolysaccharidosis. 1. p-Glucuronidase 2. IV-Acetylgalactosamine-4-sulfatase 3. p-W-Acetylhexosaminidase 4. fl Acetylgalactosamine-6-sulfatase 5. p-Galactosidase 6. W-Acetylglucosamine-6-sulfatase 7. lduronate-2-sulfatase 8. L-lduronidase 9. o-A/-Acetylglucosami-nidase 10. Heparan Af-sulfatase.

HA as other polysaccharides is synthesized from nucleotide sugars in this case UDP-glucuronic acid and UDP-W-acetylglucosamine [11]. The initiation mecha-... 

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