Chitin initiation

Liquid crystalline behavior occurs in the exocuticle of certain classes of beetles. The bright iridescent colors that are reflected from the surface of Scarabaeid beetles originates from a petrified chiral nematic stmctural arrangement of chitin crystaUites in the exocuticle (38). It is suggested that this chiral nematic texture forms spontaneously in a mobile, Hquid crystal phase that is present during the initial stages of the exocuticle growth cycle. 

Chitosan, having a similar chemical backbone as cellulose, is a linear polymer composed of a partially deacety-lated material of chitin [(l-4)-2-acetamide-2-deoxy-/3-D-glucan]. Grafting copolymer chains onto chitosan can improve some properties of the resulting copolymers [48-50]. Yang et al. [16] reported the grafting reaction of chitosan using the Ce(IV) ion as an initiator, but no detailed mechanism of this initiation has been published so far. 

Thus in this example the tetramer serves as both the donor and the acceptor. Usui et al, (43) propose this reaction for the synthesis of hexa-N-acetylchitohexaose, an oligosaccharide with reported antitumour activity (24), They dso observed formation of heptamer by incubating the pentamer wiA the Nocardia enzyme, but no chain elongation was observed with tiie hexamer as initial substrate. Similar activities with the formation of chitin oligosaccharides have also been observed for... 

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]. 

Yu, C., Bassler, B. L., and Roseman, S., Chemotaxis of the marine bacterium Vibrio fumissii to sugars. A potential mechanism for initiating the chitin catabolic cascade,./. Biol. Chem., 268, 9405, 1993. 

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