Al-Acetyl-D-glucosamine

Sashiwa, H., Fujishima, S., Yamano, N. et al. 2003. Enzymatic production of Al-acetyl-D-glucosamine from chitin. Degradation study of Al-acetylchitooligosaccharide and the effect of mixing of crude enzymes. Carbohydr. Polym. 51 391-395. 

Okamoto, Y, Minami, S., Matsuhashi, A. et al. 1993. Polymeric Al-acetyl-D-glucosamine (chitin) induces his-tionic activation in dogs. J. Vet. Med. Sci. 53 121-140. 

Chromatographic experiments on the formation of the chromogen shows that three chromogens were formed in the presence of each other, and they were called I, II, and III by Kuhn et al. Chromogen III forms only in small yield, by the action of hot dilute sodium carbonate solution on V-acetyl-D-glucosamine. It is formed in larger yield when V-acetylglucosamine is refluxed with pyridine. 3-Acetamidofuran also forms in small quantity. 

The 2, 3 -epoxypropyl jS-glycoside of di(N-acetyl-D-glucosamine) where R is N-acetyl glucosamine specifically inactivates hen lysozyme and several other bird lysozymes (Maron et al. 1972). The residue of hen lysozyme specifically modified by VIII is asp. 52 (Eshdat et al. 1973). X-ray analysis reveals that the two glucosamine residues of the affinity label occupy subsites B and C of the substrate binding cleft (Moult et al. 1973). The synthesis of the affinity label was accomplished by the most general procedure for the synthesis of epoxides, namely oxidation of alkenes with peroxyacids. 

Figure 17-33. Synthesis of N-acetylneuraminate (Neu5Ac) from N-acetyl-D-glucosamine (GIcNAc) and pyruvate through N-acetyl-D-mannosamine (ManNAc) with N-acetylneuraminate and N-acetyl-D-glucosamine 2-epimerase. Reprinted from Maru et al.I259].

Chitin is a homopolymer of AT-acetyl-D-glucosamine residues and is a major structural component in the exoskeletons of crustaceans, mollusks, arthropods, and the cell walls of numerous fungi and algae. Owing to its widespread presence in both terrestrial and aquatic organisms, chitin is second only to cellulose as the most abundant biopolymer on the Earth (Shahidi and Abuzaytoun, 2005). On a dry weight basis, shrimp, crab, lobster, prawn, and crayfish have been reported to contain between 14% and 35% chitin, while deproteinized dry shell waste of Antarctic krill contains approximately 40% crude chitin (Haard et al, 1994). Crustaceans are the primary sources of chitin used in industry. Chitin can be extracted from shellfish and crustacean waste by mixing with a dilute add to induce demineralization, followed by a deproteini-zation step in a hot alkaline solution (Synowiecki and Al-Khateeb, 2003). 

Chitosan is a linear copolymer composed of N-acetyl-D-glucosamine and D-glucosamine units [Fig. 16.4). It is derived from alkaline deacetylation of chitin that is the second most abundant polysaccharide next to cellulose [Fig. 16.4) [Sloan, 1992). Chitin is the main component in the shells of crustaceans such as shrimp, crab, and lobster. It is also found in the exoskeleton of mollusks and insects, and the cell walls of some fungi [Rlnaudo, 2008 Raabe et al., 2007 Vincent and Wegst, 2000). 

---