Chitin nature

Macromolecules may be classified according to different criteria. One criterion is whether the material is natural or synthetic in origin. Cellulose, lignin, starch, silk, wool, chitin, natural rubber, polypeptides (proteins), polyesters (polyhydroxybutyrate), and nucleic acids (DNA, RNA) are examples of naturally occurring polymers while polyethylene, polystyrene, polyurethanes, or polyamides are representatives of their synthetic counterparts. When natural polymers are modified by chemical conversions (cellulose —> cellulose acetate, for example), the products are called modified natural polymers. 

Chretiennot-Dinet MJ, Giraud-Guille M-M, Vaulot D, Putaux J-L, Saito Z, Chanzy H (1997) The chitinous nature of the filaments ejected by Phaeocystis (Prymnesiophyceae). J Phycol 33 666-672 Crame JA (1993) Latitudinal range fluctuations in the marine realm through geological times. Trends Ecol Evol 8 162-166... 

Chitosan is a 3-1,4-linked glucosamine polymer and partially deacetylated form of chitin. Naturally, it is present as a major component of the Zygomycete cell walls and usually obtained by artificial deacetylation of chitin. Chitosanase (EC 3.2.1.99) is a hydrolytic enzyme which catalyzes the breakdown of chitosan into glucosamine oligomers (1). It has been isolated from several microorganisms inchidmg Streptomyces (2), Pseudomonas (3), Bacillus (4), Penicillium (5) and Fusarium (6). 

Foster, A.B. and Hackman, R.H. 1957. Application of ethylenediamine tetraacetic acid in the isolation of crustacean chitin. Nature. 180 40-41. 

Chitin naturally occurs associated with proteins, organic pigments, and minerals (Mnzzarelli 1977, No 1995). Among them, proteins possess functional (amine and NH-C=0) groups similar to chitin/chitosan. The impurities and moisture create interference peaks, and change the positions... 

For a review of the isolation of chitin from natural sources and some of its uses see the November 1990 issue of the Journal of Chemical Education (pp 938-942)... 

Plant stmctural material is the polysaccharide cellulose, which is a linear P (1 — 4) linked polymer. Some stmctural polysaccharides iacorporate nitrogen iato thek molecular stmcture an example is chitin, the material which comprises the hard exoskeletons of kisects and cmstaceans. Chitki is a cellulose derivative whereki the OH at C-2 is replaced by an acetylated amino group (—NHCOCH ). Microbial polysaccharides, of which the capsular or extracellular (exopolysaccharides) are probably the most important class, show more diversity both ki monomer units and the nature of thek linkages. 

Last years the concern of the scientists and contributors to chitin, chitosan and chitincontaining connections has increased. It is connected to their widespread occurrence in the nature, paiticulai properties, and also feasibility in many areas of a national economy. The raw sources for obtaining chitincontaining of products are the testas of crabs, lobsters, shrimps, and also cabbage-weeds, funguses. 

Thus, based on material applications, the following polymers are important natural rubber, coal, asphaltenes (bitumens), cellulose, chitin, starch, lignin, humus, shellac, amber, and certain proteins. Figure 4 shows the primary structures of some of the above polymers. For detailed information on their occurrence, conventional utilization, etc., refer to the references cited previously. 

M. Poulicek, M. S. Voss-Foucart, and Ch. Jeuniaux, Chitin in Nature and Technology (M. Muzzarelli, Ch. Jeuniaux, and G. W. Gooday, eds.) Plenum Press, New York (1986). 

Many years ago chitin was seen as a scarcely appeahng natural polymer due to the variety of origins, isolation treatments and impurities, but the works of several analytical chemists and the endeavor of an increasing number of companies have qualified chitins and chitosans for sophisticated applications in the biosciences. Chemistry today offers a range of finely characterized modified chitosans for use in the biomedical sciences. Moreover, surprising roles of these polysaccharides and related enzymes are being unexpectedly discovered [351]. 

Muzzarelli RAA, Jeuniaux C, Gooday GW (eds) (1986) Chitin in Nature and Technology. Plenum, New York NY... 

The natural polymers in common use are cellulose, lignin, chitin, starch and guar gum. The natural products had complete... 

Chitin in nature, Ed. R A Muzzarelli, C Jeuniaux and G W Gooday (New York Plenum Press, 1986). 

There are several reports on the coating of bone-like hydroxyapatite onto natural polymer substrates. Kawashita et at. [57] reported that carboxymethylated chitin and gellan gum gels, which have carboxyl groups, can form hydroxyapatite on their surfaces in SBF if they are treated with a saturated Ca(OH)2 solution in advance, while curdlan gel, which has no carboxyl group, does not form hydroxyapatite in SBF, even if it is treated with Ca(OH)2 solution. These results support the hypothesis that carboxyl groups induce hydroxyapatite nucleation. Kokubo et at. [58,59] reported that non-woven fabrics of carboxymethylated chitin and alginate fibers also form hydroxyapatite on their surfaces in SBF if they are treated with Ca(OH)2 solution. 

Chitosan is a naturally amine-functionalized polysaccharide which is easily obtained by deacetylation of chitin, a zero-cost residue of the seafood industry (Fig. 

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