A-Chitin

Note a, b, and e are in A. a = p= 90 and 7 are in degress. a Chitin I and U were originally termed [S- and a-chitin, respectively. b Non-half-staggered double helix. e Capsular polysaccharide. 

Chitosan scaffolds were reinforced with beta-tricalciiun phosphate and calcium phosphate invert glass [177]. Along the same line, composites of Loligo beta-chitin with octacalcium phosphate or hydroxyapatite were prepared by precipitation of the mineral into a chitin scaffold by means of a double diffusion system. The octacalciiun phosphate crystals with the usual form of 001 blades grew inside chitin layers preferentially oriented with the 100 faces parallel to the surface of the squid pen and were more stable to hy-... 

One of the simplest ways to prepare a chitin gel is to treat chitosan acetate salt solution with carbodiimide to restore acetamido groups. Thermally not reversible gels are obtained by AT-acylation of chitosans N-acetyl-, N-propionyl- and N-butyryl-chitosan gels are prepared using 10% aqueous acefic, propionic and bufyric acid as solvents for treatment with appropriate acyl anhydride. Both N- and 0-acylation are found, but the gelation also occurs by selective AT-acylation in the presence of organic solvents. 

Therefore, the ability of certain POs to bind with chitin is a widespread phenomenon and -possibly - connected with the defence reactions of the organisms to pathogen attacks. Since it was shown that some biogenic molecules - such as chitooligosaccharides or salicylic acid -can activate an anionic POs, we might suggest that an application of these compounds optimises the process of anionic PO isolation with a chitin. 

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. 

Fusion vectors are available that combine a recombinant protein with a mutant mini intein segment (not containing an endonuclease domain) and followed by a chitin binding domain (CBD Zhang et al., 2001). These mutants typically also have an alanine substitution that replaces the cysteine or serine/threonine usually found on the C-extein splice junction. Alanine... 

Prepare a chitin affinity column by washing with at least 10 bed volumes of 25 mM HEPES, 250mM NaCl, ImM EDTA, 0.1 percent Triton X-100, pH 7.0 (wash buffer). 

Ho, C.M., T.R. Hsu, J.Y. Wu, and C.H. Wang. 1987. Effect of dimilin, a chitin synthesis inhibitor, on the growth and development of larvae of Aedes albopictus Skuse. Chinese Jour. Entomol. 7 131-141. 

ClandoSan is a chitin protein found in crasta-cean shells and is labeled for nematode control. ClandoSatf is a new product still being evaluated. The product acts to stimulate the growth of certain soil microorganisms that produce chitanase and other enzymes that destroy plant-pathogenic nematodes. 

A full-length human csk DNA that codes for Csk, a 50-kDa protein that catalyzes the phosphorylation of a tyrosine within the C-terminal tail of Srk, was inserted in a plasmid and in-frame with a modified intein-chitin binding domain (CBD) encoding sequence, where intein is a protein-splicing element. 130 The expressed protein underwent a conversion into a thioester of the N-terminal cysteine of the intein, but the normal second step of an intein splicing did not occur. The protein was then bound to a chitin resin and washed. The resin containing the bound protein was treated with 2% benzenethiol to cleave the thioester and give the free phenyl thioester, which was immediately treated with one of the synthetic... 

Electron-diffraction patterns for a-chitin from the grasping spines of the marine worm Sagitta led to an orthorhombic unit-cell, with a = 0.474 nm, b = 1.886 nm, and c = 1.032 nm. The appearance of the 001 (1, odd) and OkO (k, odd) reflections cast doubt on the P21212, space group proposed by Blackwell and coworkers.60,61... 

In the more abundant a chitin the chains in alternate sheets have opposite orientations,101102 possibly a result of hairpin folds in the strands. Native chitin exists as microfibrils of 7.25 nm diameter. These contain a 2.8-nm core consisting of 15-30 chitin chains surrounded by a sheath of 27-kDa protein subunits. The microfibrils pack in a hexagonal array, but the structure is not completely regular. Several proteins are present some of the glucosamine units of the polysaccharide are not acetylated and the chitin core is often calcified.103 The commercial product chitosan is a product of alkaline deacetylation of chitin but it also occurs naturally in some fungi.102 Chitin is also present in cell walls of yeasts and other fungi. It is covalently bonded to a P-l,3-linked glycan which may, in turn, be linked to a mannoprotein (see Section D,2)97... 

Figure 4.8 The intein system as used for fusion proteins (Xu, 2000). The fusion proteins undergo self-cleavage at the upstream splice junction. The amino acids that participate directly are shown, and the remainder of the intein and target protein are drawn as boxes. Usually, the intein is conjugated to a chitin-binding domain, so purification of the fusion protein can occur by using a chitin-conjugated column. Self-cleavage can occur overnight.

Figure 6. R-map for a-chitin variation of R" with and 2, the CHtOH orientations on neighboring chains. The dashed line corresponds to P2,2,2, models,...

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