Cellulose Chitin

The parallels among chitin, cellulose, and HA structures, all being j3 -chains of hexose polymers are reflected in the striking similarity in sequence between the HAS from vertebrates, cellulose synthases from plants, and chitin synthases from fungi. A primordial ancestral gene must have existed from which all of these enzymes evolved that are involved in the biosynthesis of all polymers that contain -glycoside linkages, an ancient j3-polysaccharide synthase. 

Hirano, S., Zhang, M., Chung, B.G., and Kim, S.K. 2000. The A-acylation of chitosan fibre and the A-deacetylation of chitin fibre and chitin-cellulose blended fibre at a solid state. Carbohydr. Polymers 41, 175-179. 

What is chitin Cellulose and chitin are polymers based on single kinds of monomer units—glucose and Af-acetylglu-cosamine, respectively. Both polymers play structural roles in organisms. 

Takegawa A, Murakami M, Kaneko Y, Kadokawa J (2010) Preparation of chitin/cellulose composite gels and films with ionic liquids. Carbohydr Polym 79 85-90... 

Several natural polymers as chitin, cellulose, functionalized cellulose and natural fibers are some of most studied natural polymers in graft copolymerization using redox system as initiator, being cerium ion one with more reports. 

The reaction is done at a pFl of 9-11. There the hydrolysis of the product chitin is much suppressed. The degree of polymerization of synthetic chitin is some 10-20 depending on the reaction conditions (50). Peracetyloxazolines can be obtained from peracetyl saccharides (51). A facile preparation method of chitin cellulose composite films has been described (52). Hereby ionic liquids are used, l-aUyl-3-methylimidazolium bromide and l-butyl-3-methyl-imidazoUum chloride. The former liquid dissolves chitin and the latter Uquid dissolves cellulose. 

Kondo T., Kasai W., and Brown, Jr. R.M. 2004. Formation of nematic ordered cellulose and chitin. Cellulose 11 463 74. 

Hirano, et al. 59 Chitin-cellulose-silk fibroin Sodium chitin xanthate-sodium cellulose xanthate-silk fibroin aq. 5% NaOH aq. 10% H2SO4 and 40-43% (NHiIjSOi... 

Tang, H., Chang, C. Zhang, L. (1911) Efficient adsorption of Hg + ions on chitin/cellulose composite membranes prepared via environmentally friendly pathway. Chemical Engineering Journal, 173, 689-697. 

With the appropriate design of monomers, the following three hybrid polymers, chitin-cellulose hybrid with DP value 22 in 79% yields, chitin-chitosan hybrid with 4280 in 75% yields,and a water-soluble chitin-xylan hybrid with 2730 in 80% yields, have successfully been synthesized (Scheme 37). In all EROPA reactions, structural control is perfect, having ay (l 4) glycosidic linkage. 

Glucose molecules are bound in starch by the easily hydrolyzed a bonds. The same type of bond can also be seen in the animal reserve polysaccharide glycogen. This is in contrast to many structural polysaccharides such as chitin, cellulose and peptidoglycan, which are bound by P-bonds and are much more resistant to hydrolysis. A starch branching enzyme introduces 1,6-a glycosidic bonds between these chains, creating the branched amylopectin (Figure 5.28). 

A series of biofibers based on chitin and chitosan has been prepared by wet spinning and post modification of chitosan fibers as recently reviewed by Hirano [145]. These biofibers based on chitin, chitosan, chitin-cellulose, chitosan-cellulose-silk fibroin, chitosan-tropocollagen, and chitin-cellulo-silk fibroin have been proposed for applications including antithrombogenic, antimicrobial, hemostatic, and wound healing [145]. N-hexanoyl, and N-octanoyl chitosan are antithrombogenic and emocompatible. 

Fungi are also called true fungi/Eumycetes, which are nucleated, non-chlorophyll unicellular organisms. The organisms possess spores, filaments, as well as somatic and chitin/cellulose-made cell walls (Badwan et al., 1985]. 

Schizomycophyta Myxomycopkyta EumycophyUt (bacteria, molds, and fungi) chitin cellulose mannans starches levans glycogen extracellular polysaccharides... 

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