Biopolymers chitin

The arsenal of plant defense peptides contains members capable of binding carbohydrate residues, namely /31-4 linked A -acetyl glucosamine residues that form the biopolymer chitin. The actual mode of action remains unclear. Antifungal and antimicrobial activity has been shown in vitro. For example Ac-AMP2 is a small disulfide-rich chitin-binding peptide isolated from the seeds of Amaranthus caudatus with antimicrobial activity. It differs from Ac-AMP 1 by one additional arginine residue at the C-terminus. The structure was determined by NMR and contains a cystine knot motif. Ac-AMP2 displays a so-called hevein domain partly... 

The reaction appears to be well suited for selective conversion of biomass carbohydrates into their corresponding oxidized derivatives. This system serves to oxidize several polymeric carbohydrates including starches and pullulan.445 49 More recent work has described the TEMPO-catalyzed introduction of carboxyl groups in native cellulose and its different morphological forms,45(M52 cellulose derivatives,453 and the surface of cellulose nanocrystals.454 The related biopolymer, chitin, also is oxidized under these conditions.455... 

In addition, FTIR was useful to elucidate about interactions between polymeric matrix (polyurethane) and biopolymer (chitin). However, it is necessary to obtain thinner samples in order to see specific interaction in the interface of materials. 

The second most abundant biopolymer chitin and its deacetylated form chitosan have a wide range of applications, including in the food industry. Insolubility at neutral pH is a major factor which limits the food applications of these two biopolymers and has attracted the attention of scientists toward the depolymerized oligosaccharide form of chitosan, which is soluble at neutral pH. Therefore, COS can be applied in the many fields where the insolubility of chitin or chitosan is becoming a limiting factor, especially in the food industry. 

With repetitive functional groups, biopolymers provide excellent chelating and complexing materials for a wide variety of pollutants including dyes, heavy metals and aromatic compounds. The biopolymers chitin and chitosan are very much active towards the metal removal due to the presence of its functional groups. Chitin contains the hydroxyl and acetamido functional groups and chitosan contains hydroxyl and amine functions. 

The same questions about the safety of organic flocculants have been raised ia other countries. The most drastic response has occurred ia Japan (7,77) and Swit2edand (77) where the use of any synthetic polymers for drinking water treatment is not permitted. Alum and PAC are the principal chemicals used ia Japan (7). Chitin, a biopolymer derived from marine animals, has been used ia Japan (80,81). Maximum allowed polymer doses have been set ia Prance and Germany (77). 

The chitin is modified to impart the structure required by the functions of each particular tissue, via crystalHzation, deacetylation, cross-finking to other biopolymers (Fig. 1), and, in certain cases, quinone tanning. The resulting complex structures are capable of exceptional performances [15]. 

Partially deacetylated chitin, a cellulose-like biopolymer consisting predominantly of N-acetyl-D-glucosamine chains, in the form of films or crosslinked hydrogels has been used for the delivery of drugs (28,29). The suitability of chitin as a vehicle for the sustained release of drugs was examined using indomethacin and papaverine hydrochloride as model drugs (30). In vitro studies showed that over 80% of the indomethacin was released within 7 hr, whereas papaverine hydrochloride dissolved almost immediately. 

Henderson, W., Olsen, G.M., and Bonnington, L.S. (1994) Immobilized phosphines incorporating the chiral biopolymers chitosan and chitin./. Chem. Soc. Comm., 1863-1864. 

Chitin and the deacetylated form, chitosan, are attractive linear amino polysaccharides found in the shell of crustaceans. These abundant biopolymers, composed mainly of poly(/T(l,4)-2-acetamido/2-amino-2-deoxy-D-glucopyranose)... 

Chitin, a polymer of N-acetylglucosamine, is present in large amounts in the exoskeletons of crustaceans and other arthropods and is a major marine biopolymer 16). Its availability is, however, limited to byproducts from seafood industries (76). 

Chitin is an abundant biopolymer, especially in Perth where the thriving Western rock lobster industry produces tonnes of waste, a good proportion of which is exoskeleton and rich in chitin. It has been our aim for some years to put this waste chitin to some good use and so, initially, we have set out to prepare epoxyalkyl glycosides based on W-acetyl-D-glucosamine and its oligomers, for example 60 and 61. It is hoped that molecules such as 60 and 61 will prove to be efficient inhibitors of chitinases, ubiquitous enzymes involved in many biological processes [42]. 

Chitosan Chitosan has a molecular structure similar to cellulose. This material is produced from chitin, which is widely found in the exoskeleton of shellfish and crustaceans. Chitin is the second most abundant natural biopolymer after cellulose. Chitosan is a good adsorbent for all heavy metals. It has been estimated that chitosan can be produced from shellfish and crustaceans at a market price of 15.43 /kg. 

Kurita, K. (2006). Chitin and chitosan Functional biopolymers from marine crustaceans. Mar. Biotechnol. 8,203-226. 

This subject has been of continuing interest for several reasons. First, the present concepts of the chemical constitution of such important biopolymers as cellulose, amylose, and chitin can be confirmed by their adequate chemical synthesis. Second, synthetic polysaccharides of defined structure can be used to study the action pattern of enzymes, the induction and reaction of antibodies, and the effect of structure on biological activity in the interaction of proteins, nucleic acids, and lipides with polyhydroxylic macromolecules. Third, it is anticipated that synthetic polysaccharides of known structure and molecular size will provide ideal systems for the correlation of chemical and physical properties with chemical constitution and macromolecular conformation. Finally, synthetic polysaccharides and their derivatives should furnish a large variety of potentially useful materials whose properties can be widely varied these substances may find new applications in biology, medicine, and industry. 

Other natural ingredients identified as allergens in moisturizers are placenta,70 chitin (a celluloselike biopolymer and important structural element of the integuments of arthropods, particularly crustaceans, mollusks, unicellular micro-organisms, seaweed, and fungi), and chitosan (deacetylated chitin).78-79... 

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