Lobster tendon

In reexamining the structure (6) we utilized intensity data for 45 observed reflections in deproteinized lobster tendon (Homarus americanus). The unit cell contains disaccharide sections of two chains, and the model was refined in terms of the following parameters ... 

FIGURE 2.21 NMR solid-state spectra of (a) a-chitin from deproteinized lobster tendon, (b) p-chitin from dried deproteinized tube of Tevnia jerichonana. 

Assigned carbon atom Anhydrous p-chitin from diatom spines (ppm) a-Chitin from lobster tendon (ppm)... 

The x-ray fiber diffraction data of chitosan was first derived from the solid-state deacetylated product of a lobster tendon chitin by Clark and Smith (1936). Sixty years later, Okuyama et al. (1997) analyzed the pattern of tendon chitosan. In the tendon polymorph, the chitosan chains and water molecules are packed in an orthorhombic unit cell. Each chitosan chain takes an extended... 

Fig. 12.—Electron Micrograph of Mandibular Tendon of Lobster Dispersed with a Waring Blendor. (Fibrillar texture is similar to that of cellulose, with fibrils down to 150 A. visible.)...

In the solid state, chitin mainly occurs as two allomorphs, the a- and (3-forms, which are differentiated by infrared and solid state NMR spectroscopies and X-ray diffraction [3,4]. a-chitin is the most abundant, occurring in krill, lobsters and crab tendons, shrimp and crab shells. It also results from recrystallization of (3-chitin in solution treated with strong aqueous HCl (over 7N) and washed with water because the a-form is thermodynamically more stable than (3-chitin [5]. (3-chitin is found in association with proteins in squid pens [3, 6] or in the tubes synthesized by pogonophoran and vestimetiferan worms [7,8]. In the solid state, the chains are parallel in (3-chitin and antiparallel in a-chitin. Their crystalline structures were reviewed in different papers [1, 4, 9-13]. Chitin is insoluble in all the usual solvents while taking into account their crystalline forms (a or (3) because the reactivity of p-chitin is larger than that of the a-isomorph, which is important for enzymatic and chemical transformations of chitin [14]. 

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