Lobster shells

The preparation of glucosamine hydrochloride from lobster shells and crab shells by essentially this method has been reported by Irvine, McNicoll, and Hynd and Hudson and Dale. Other methods involving the use of cicad larvae shells and shrimp shells ls also have been reported. 

An excellent case in point is the coloration of the American lobster, Homarus americanus. The pigment associated with the typical greenish-brown outer layer of the lobster shell is the carotenoid, astaxanthin (Figure A), an oxygenated derivative of p-carotene, also known as the molecule that imparts the orange color to carrots. 

Polyenes exhibit two strong Raman bands between 1600 and 1500 cm and between 1200 and 1100 cm , respectively. These are attributed to in-phase vibrations of the C=C and C-C bonds, respectively, throughout the entire chain. Examples include all-trans-retinol (Fig. 4.1-6B), /3-carotene, and carotene-containing proteins, obtained, for instance, from lobster shells (Rimai et al., 1973 Oseroff and Callender, 1974). Polyene sequences with approximately twenty conjugated double bonds, formed by HCl elimination from polyvinyl chloride as a result of aging, also show these Raman bands at 1495 and 1115 cm (Peitscher and Holtrup, 1975). These bands are enhanced as a consequence of the resonance Raman effect, which makes it possible to detect such groups in polymers and natural materials, even at low concentration. 

The coral Allopora californica also contains a purple-blue complex between (3.S,3 5)-astaxanthin and protein." Both these proteins are relatively simple structures, with molecular weight < 80 000 daltons. Photoacoustic spectroscopy has indicated the presence of a variety of carotenoprotein species in lobster shell, the distribution varying with the depth into the shell.Resonance Raman spectroscopy has revealed that the lobster egg pigment ovoverdin contains two astaxanthin molecules at different sites in the protein. "... 

Other Spectroscopic Techniques. Photoacoustic spectroscopy has been used to investigate the carotenoproteins of lobster shell.Visual pigments and bacteriorhodopsin have been studied by linear dichroism/ neutron diffraction/ and emission spectroscopy. ... 

Methods used for the preparation of chitin from lobster shell are equally applicable to fungi. Successive extraction with aqueous acid and hot, aqueous alkali leaves chitin as an insoluble residue. 

A hole in the peak of the helmet allows it to hang in front of the wearer s face. This contrivance should be made of wood, the helmet to be modeled in three pieces, the skullcap, peak and lobster shell neck guard tn one piece, and the ear guards in two pieces, one for each side. The center of the ear guards arc perforated. All of the helmets are made in the same... 

D-linear Crab and lobster shells, fungi Chitin... 

D-Glucosamine (10 g 2) is obtained from the chitin of lobster shells by HCl hydrolysis under similar conditions as described for glucose. 

Polymers as solids are ubiquitous in our modern society. They are some of the most common synthetic materials. Biologically derived macromolecules are also abundant. Whether it is a piece of wood, a natural fiber, or a lobster shell, nature uses solid organic macromolecular materials as key architectural material. This abundance of examples of synthetic and natural solid polymeric materials is mirrored in the prevalence with which insoluble cross-linked polymer supports are used in synthesis and catalysis [23-25]. However, while solid-phase synthesis and related catalysis chemistry most commonly employ cross-linked supports that resemble those originally used by Merrifield [26], the polymers found in nature are neither always insoluble nor always cross-linked. Indeed, soluble polymers are as common materials as their insoluble cross-linked analogs. Moreover, nature quite commonly uses soluble polymers as reagents and catalysts. Thus, it is a bit surprising that synthetic soluble polymers are so little used in chemistry as supports for reagents, substrates, and catalysts. 

Carotenoids Many in vivo situations e.g. photosynthetic membranes lobster shells Polyene Polyene conformation polyene-polyene exciton interactions membrane potential triplet state properties "... 

Chitin (Fig. 3.1) is also a biopolymer that is abundant in nature. It is isolated from crab, shrimp, and lobster shells as a byproduct of the seafood industry. Worldwide, several million tons of chitin are generated annually as waste by the seafood industry. Chitin has been successfully prepared by several methods such as enzymatic methods, methods using hydrolytic conditions of boiling HCl and vigorous stirring, and methods using chitin whiskers of slender parallelepiped rods. Previous research has reported the preparation of presumably functional chitin nanoparticles and their... 

Chitin exists in three polymorphic forms, depending on the arrangements of the chains in the microfibrils a-, [)- or y-chltin, in which the molecules have antiparallel, parallel or mixed arrangements, respectively. The most common form is a-chitin [45], being found in shrimp, prawn, crab and lobster shells, while p-chltin is found in mol-lusks such as squids [86] y-chitin is found in the cell walls of fungi [118]. 

Crab, shrimp, and lobster shells, waste products of the sea food industry, are the best sources of the polysaccharide. Calcium carbonate is first removed by hydrochloric acid and then protein and other organic impurities by extraction with sodium or potassium hydroxide solutions. Complete acid hydrolysis of chitin, although requiring drastic conditions, yields almost theoretical amounts of D-glucosamine and acetic acid (Chapter VIII), whereas controlled acid or enzyme hydrolysis produces V-acetyl-D-glucosa-mine. Acetolysis of chitin or acetylation of the partial acid hydrolysis products gives among other products chitobiose octaacetate which has been... 

Calcium and oxygen are major players in other external materials encountered in nature beyond shells and bones. Abalone shells, deer antlers, lobster shells, sponge skeletons, bird-of-paradise stems, porcupine quills, toucan beaks, and feathers are all listed in a single review on biomimetic materials, and all are linked with calcium, oxygen, and/or oxidized crosslinks. This is what calcium and oxygen made possible right before the Cambrian explosion. 

Absorption spectra of turbid materials and even of specimens as dense as intact leaves or lobster shells also can be measured by photoacoustic spectroscopy. A photoacoustic spectrometer measures the heat that is dissipated when a sample is excited by light and then decays nonradiatively back to the ground state. In a typical design, release of heat causes a gas or liquid surrounding the sample to expand and the expansion is detected by a microphone. Such measurements can be used to... 

Astaxanthin is present in crab and lobster shells and lobsters, the red astaxanthin is released from and, in combination with proteins, provides three a green carotenoid-protein complex. Astaxanthin blue hues (a-, 3- and y-crustacyanin) and one usually occurs in lobster shell as an ester, e. g., diyellow pigment. During the cooking of crabs palmitic ester. 

Y. Ando, E Pukada, and M. J. Olimeber, Piezoelectricity of ckitin in lobster shell and apo-detne, BiorheoU 14 175 (1977). 

Another structural variation replaces a hydroxyl group with an amine group and its derivatives. These amino sugars are components of some antibiotics. They also occur in polysaccharides contained in the exoskeleton of arthropods and are components of blood group antigens. The polysaccharide found in lobster shells contains the iV-acetyl derivative of d-2-glucosamine that is, it is A -acetylglucosamine. 

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