O-Chitin

Sulfates o II H-O-S-O-R II o Chitin sulfate, arylsulfate esters, aromatic sulfate esters ls-Jt 2481.5-2482... 

Senda, T., He, Y. and Inoue, Y. (2002) Biodegradable blends of poly(E-caprolactone) with o-chitin and chitosan specific interactions, thermal properties and crystallisation behaviour. Polymer International, 51,33-39. 

X-ray diffraction measurements of synthetic chitin showed a high-order structure of o -chitin having an antiparallel chain alignment and a thermo-... 

Fig. 15 X-ray diffractograms of a artificial chitin, b natural o -chitin from queen crab, and c natural )6-chitin from squid pens...

Figure 7. Cascade mechanism o activation o chitin synthesis in yeast.

Muzzarelli, R. A. A., Tubertini, O. Chitin and chitosan as chromatographic supports and adsorbents for from organic and aqueous solutions and seawater. Talanta. 1969,... 

The accessibility of chitin, mono-O-acetylchitin, and di-O-acetylchitin to lysozyme, as determined by the weight loss as a function of time, has been found to increase in the order chitin < mono-O-acetylchitin < di-O-acetylchitin [120]. The molecular motion and dielectric relaxation behavior of chitin and 0-acetyl-, 0-butyryl-, 0-hexanoyl and 0-decanoylchitin have been studied [121,122]. Chitin and 0-acetylchitin showed only one peak in the plot of the temperature dependence of the loss permittivity, whereas those derivatives having longer 0-acyl groups showed two peaks. 

Numerous substituted derivatives of chitin and chitosan are known [67] some important examples are shown in Scheme 10.9. The possibility of forming either anionic (5,7,8,11) or cationic (9,12) derivatives should be noted. The O-carboxymethyl (5) and N-carboxymethyl (11) polymers are of particular interest as they have stronger complex-forming capabilities with metal ions than either unsubstituted chitosan or EDTA [65]. In practice, derivatives formed by substitution via the 2-amino group of chitosan are more common than those substituted via the 6-hydroxy position of the glucopyranose grouping [65]. 

Typical derivatives of chitin (1) and chitosan (2) [67] alkali-chitin (3), O-acylchitin (4), O-carboxymethylchitin (5), O-hydroxyethylchitin (6), chitin O-sulphate (7), chitin O-phosphate (8), chitosan salt (9), /V-acylchitosan (10), /V-carboxymethylchitosan (11), trialkylammonium salt (12)... 

Fig. 10.4. (Opposite) Alignments of nematode chitinases with the active centre boxed. Identical amino acids are marked with an asterisk ( ) similar amino acids are marked with a dot (.). Conserved cysteine residues in the chitin-binding domain are printed in bold. Gene Bank accession numbers C.eleg. Chit (C. elegans), Q11174 OvL3 Chit (O. volvulus), L42021 AvL3 Chit (A viteae), U14638 B.m. Chit(B. malayi), M73689.

Renkema, G.H., Boot, R.G., Au, F.L., Donker-Koopman, W.E., Strijland, A., Muijsers, A.O., Hrebicek, M. and Aerts, J.M. (1998) Chitotriosidase, a chitinase, and the 39-kDa human cartilage glycoprotein, a chitin-binding lectin, are homologues of family 18 glycosyl hydrolases secreted by human macrophages. European Journal of Biochemistry 251, 504-509. 

It is worth pointing out that, besides o-sorbitol 19 and D-mannitol 36, other low-molecular weight building blocks have been already obtained on the ton-scale from low cost or waste polymeric carbohydrates (starch, cellulose, hemicellulose, chitin) [80, 81]. Most of these compounds are densely functionalized enantiopure molecules that can be easily converted into high-value added products, including chiral ionic liquids. Therefore, further studies are required to develop other synthetic approaches to environmentally sustainable ionic liquids based on renewable raw materials. 

Chitin and chitosan derivatives have also been studied as blood compatible materials both in vivo and in vitro [520], Anticoagulant activity was greatest with O sulfated N acetyl chitosan, followed by N,0 sulfated chitosan, heparin, and finally sulfated N acetyl chitosan. The lipolytic activity was greatest for N,0 sulfated chitosan followed by heparin. The generally poor performance of chitosan was attributed to polyelectrolyte complexes with free amino groups present on the membrane surface. The O sulfate or acidic group at the 6 position in the hexosamine moiety was identified as the main active site for anticoagulant activity. 

USEPA (2001) Chitin Poly-N-acetyl-o-glucosamine (128991) Fact Sheet http // www.epa.gov/oppbppdl/biopesticides/ ingredients / factsheets / factsheeCl 28991. htm (last accessed 30 April 2010). 

FIGURE 7-18 Chitin. (a) A short segment of chitin, a homopolymer of N-acetyl-o-glucosamine units in 01 -e>4) linkage, (b) A spotted June beetle (Pellidnota punetatia), showing its surface armor (exoskeleton) of chitin. 

Meyer H.Wehrli, Helv 20, 353(1937) CA 31, 5807(1937) 5)M.L.Wolfrom et al, JACS 65, 2084(1943) 6)M.L.Wolfrom et al, Ohio State Univ Final Rept, Project 459, Columbus, Ohio(Jan 1953)pp 1,3 34 Nitrated Deacetylated Chitine A wh flocculent ppt contg 11=6 to 11,9% nitrate N(as detd by DuPont nitrometer obtd by Wolfrom et al(Ref 3) by nitrating deacetylated chitin with 100% HNOj. The nitrated product represented the combined nitrate salt nitrate ester of deacetylated chitin. This substance contd one nitric acid salt unit per anhydro-o-glucosamine unit and 1.60-1.65 nitrate ester unit per anhydro-o-glucosamine anhydro -N-acetyl-D -glucosammine units. Attempts to nitrate deacetylated chitin by means of nitrogen pent oxide, in a non-aqueous medium y in the presence of sodium fluoride, by the method of Caesar(Ref 2) were unsuccessful mainly because of occlusion of NaF in the nitrated products(Ref 3)... 

Lysozyme hydrolyses a polysaccharide present in bacterial cell walls that is a / -(l—>4) linked polymer of alternating IV-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG) residues. The enzyme only attacks the NAM—>NAG linkage. Certain lysozymes also attack chitin, the / -(l- 4) linked linear polymer of NAG (9). It was demonstrated by Rupley (5), using oligosaccharides of NAG, that the Ci-O linkage was specifically cleaved and / -configuration was retained. 

M. M. A. Olsthoorn, I. M. Lopez-Lara, B. O. Petersen, K. Bock, J. Haverkamp, H. P. Spaink, and J. E. Thomas-Oates, Novel branched nod factor structure results from a-(l->3) fucosyl transferase activity The major lipo-chitin oligosaccharides from Mesorhizobium loti strain NZP2213 bear an a-(l->3) fucosyl substituent on a nonterminal backbone residue, Biochemistry, 37 (1998) 9024-9032. 

In another oudine, cellulose was complexed with cuprammonium ions (Nicoll and Conaway, 1943). Lately, laboratory-scale isolation has relied on polar aprotic solvents and solvent systems, e.g., dimethylsulfoxide, pyridine, Af,7V-dimethylacetamide-lithium chloride, and l-methyl-2-pyrrolidinone-lithium chloride (Baker et al., 1978 McCormick and Shen, 1982 Seymour et al., 1982 Arnold et al., 1994). These solvents have enabled such homogeneous17 reactions as O- and N-derivatization of cellulose and chitin (Williamson and McCormick, 1994) and selective site chlorination (Ball et al., 1994). Dimethylsulfoxide was the solvent in a homogeneous reaction of cellulose and paraformaldehyde, prior to isolation of purified cellulose (Johnson et al., 1975). In yet another outline, paraformaldehyde enabled superior quality extracts when the parent tissues were presoaked in this solution (Fasihuddin et al., 1988). 

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