Hydrolysis of chitin

This enzyme [EC 3.5.1.41] catalyzes the hydrolysis of chitin (or, more specifically, the A-acetamido groups of A-acetyl-D-glucosamine residues in chitin) to produce chitosan and acetate. 

To investigate this possibility, chitin oligosaccharides were first prepared by acid hydrolysis of chitin and separation of the products by HPLC... 

What products would result from the partial acid hydrolysis of chitin ... 

Plants also produce structurally related enzymes (chitinases) that catalyse the hydrolysis of chitin (Table 12.2) and hence damage chitin-based insect integuments. Class I chitinases are basic enzymes with an jV-terminal hevein-related CBD and vacuole-targeting C-terminal signals whereas Class II enzymes are acidic proteins lacking these CBD and vacuole-targeting domains. Class IV chitinases are variously basic and acidic extracellular proteins with... 

Chitosan Chitosan is a nontoxic, biodegradable polymer obtained by hydrolysis of chitin, a natural polysaccharide that is a chief component of the crustacean exoskeleton. Unmodified chitosan is soluble in acidic media and has significant muco-adhesive properties. 

It is evident that any detailed mechanism of the catalytic action of lysozyme in the hydrolysis of glycosides would involve the role for proton donors and/or acceptors. The most plausible residues near the cleavage site are Asp-52 and Glu-35. The Asp residue lies in a polar environment, where it is a hydrogen bond acceptor in a complex network of hydrogen bonds. Because of its location, it has virtually a normal pK of 3.5 0.2. At pH 5.0, which is near the optimum pH value of hydrolysis of chitin by lysozyme, Asp-52 is in the ionized form. The Glu residue lies in a nonpolar region, has an increased pK, of 6.3 0.2, and would be largely un-ionized at pH 5.0. 

FIGURE 2.5 Enzymatic hydrolysis of chitin and chitosan into their monomers. 

Shrimp shell waste can be economically converted to chitin, a mucopolysaccharide (Santhosh and Mathew, 2008). This marine polysaccharide and its derivatives hold a major part in our lives as medicines, cosmetics, textiles, paper, food, and other branches of industry because of their unique nature in properties such as low toxicity, biocompatibility, hydrophobicity, etc. Hydrolysis of chitin yields a value added product, glucosamine. Carboxymethylchitin is another derivative of chitin, prepared by the carboxymethylation reaction. 

The enzymatic hydrolysis of chitin and chitosan might occur because of the action of chitinases, chitosanases, lysozymes, and cellulases (Shahidi et al., 1999). The products of chitin hydrolysis are of high degree of polymerization... 

Rupley, J.A. 1964. The hydrolysis of chitin by concentrated hydrochloric acid, and the preparation of low-molecular substrate for lysozyme. Biochem. Biophys. Acta 83, 245-255. 

On oxidation (with hypoiodite) to the corresponding aldonic acid, of the disaccharide obtained by partial hydrolysis of chitin, and acetylation with sodium acetate in acetic anhydride, the product undergoes /3-elimination, to give the bionic acid derivative 2-acetamido-4-0-(2-acetamido-tri-0-acetyl-2-deoxy- -D-glucopyranosyl)-6-0-acetyl-2,3-dideoxy-D-erj/(firo-hex-2-enono-1,5-lactone (90). In the original work, the determination of the site... 

Einbu A, Grasdalen H et al (2007) Kinetics of hydrolysis of chitin/chitosan oligomers in concentrated hydrochloric acid. Carbohydr Res 342 1055-1062... 

Konieczna-Molenda A., Fiedorowicz M., Zhong W., and Tomasik P. 2008. Polarized light-stimulated enzymatic hydrolysis of chitin and chitosan. Carbohydr Res 343 3117-3119. 

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