Chitin crab-derived

After cellulose, it is the second most abundant natural polymer found in the nature. Figure 8.9 shows the exoskeleton structure of crab shells, where chitin was derived. Chitin can also be synthesized artificially through chitinase-catalyzed polymerization of a chitobiose oxazoline derivative. Chitosan, a very important derivative of chitin, is obtained... 

Most chitins and derivatives are extracted from crab shells, lobsters and shrimps or from the waste of fungi fermentation (e.g., Aspergillus sp.) in concentrated NaOH solution. The swelling involves a modification of its natural crystal structure (a or (3). After washing in water, the recovered a structure is chemically resistant due to the hydrogen bonds between the chains. The /3-chitin... 

A contrasting picture is seen for chitosans. Chitosans—as considered in detail in the following Chapter—are derivatives of chitin (after an alkali extraction procedure) and are available in large quantities from the shells of crabs, lobsters and other crustaceans. Pure chitin is poly-N-acetylglucoasmine. The N-acetyl groups are de-acetylated in chitosan to an extent represented by ei-... 

The rich proteins from shrimp and crab are a positive notion nowadays for the supplementing of high ranked nutrition for many of the patients of nutrition depletion. The collagen and other protein disorders can be overcome by the intake of these crustaceans regularly. However, the financial limitations and the inadequacy of fishing profound disturbances due to the human population and pollution many of the developing nations are underutilize these animals. In addition, chitin and its derivatives are vastly known for their biomedical importance however, the utilization of the crustacean foods is restricted mostly to Asian countries, and many of the developed, developing, and underdeveloped countries are henceforth advised well for the proper implementation of these medicinally valuable resources. 

It is a naturally occurring horny substance which forms the framework of invertibrates(such as crabs, lobsters other mollusca), and is the animal analog of cellulose of plants. Chitin is considered a polymer, constg of more than 100 units of anhydro-N -acetylglucosamine, a deriv of D-glucose. 

The structures of chitins derived from shrimp and various kinds of crabs are all very similar. For chitin from King crab, the unit cell is orthorhombic, with a = 0.47 nm, b (fiber axis) = 1.05 nm, andc = 1.03 nm. The molecule does not take up water, and the d spacings do not vary on drying or soaking. 

The rigidity of a crab shell is due to chitin, a high molecular weight carbohydrate molecule. Chitin-based coatings have found several commercial applications, such as extending the shelf life of fruits. Processing plants now convert the shells of crabs, lobsters, and shrimp to chitin and various derivatives for use in many consumer products. 

Chitin is another highly available polysaccharide biopolymer it is derived from the exoskeleton of arthropods (specifically crab and shrimp shells) and formed from repeats of (l,4)-linked V-acetyl-p-D-glucosamine. In its natural form, the chains of... 

Hydrophilic materials include such substances as quartz, glass, metal oxides and hydroxides, oxidized minerals, etc. Alternatively, solid hydrocarbons and their fluorinated derivatives, plant leaves, the chitin shells of crabs, animal skin are all examples of objects with a hydrophobic surface. 

Chitosan, derived from crab shell chitin, is —80% deacetylated. It is dissolved in 1 M HO Ac (5 g/L) and freeze dried to yield a white, soft material. The chitosan is washed with 0.9 M A-methylmorpholine (NMM) in DMF followed by DMF. The Rink linker (0.4 mmol) is dissolved in 6 mL of DMF containing N-[(17/-benzotriazol-1 -yl)(dimethylamino)methylene]-A-methyl-methanaminium tetrafluoroborate A-oxide (TBTU) (0.3 M), HOBt (0.3 M), and NMM (0.4 M) and added to 150 mg (dry weight) of chitosan. The mixture is incubated at 45°C for 1 h, washed with DMF, and the chitosan capped with acetic anhydride-dry pyridine (1 1, v/v) for 1 h at 45°C. This procedure yields Fmoc-linker substituted chitin (Fig. 16). After drying in vacuo, the degree of substitution is determined by measuring the Fmoc released after treatment of a sample with piperidine-DMF (3 7) for 30 min at room temperature. Typically, chitosan substitution levels are 0.08-0.35 mmol/g. 

The most common biopolymers derived from animals are chitin and chito-san. Chitin is a macromolecule found in the shells of crabs, lobsters, shrimps, and insects. The primary unit in the chitin polymer is 2-deoxy-2-(acetylamino) glucose. Chitin can be degraded by chitinase. Chitosan is a modified natural carbohydrate polymer derived from deactylation of chitin, which occurs principally in animals of the phylum Arthropoda. Chitosan is also prepared from squid pens. Chitin is insoluble in its native form but chitosan, the partly deacetylated form, is water soluble. The materials are biocompatible and have antimicrobial activities as well as the ability to absorb heavy metal ions [16]. 

Chitosan is a linear copolymer composed of N-acetyl-D-glucosamine and D-glucosamine units [Fig. 16.4). It is derived from alkaline deacetylation of chitin that is the second most abundant polysaccharide next to cellulose [Fig. 16.4) [Sloan, 1992). Chitin is the main component in the shells of crustaceans such as shrimp, crab, and lobster. It is also found in the exoskeleton of mollusks and insects, and the cell walls of some fungi [Rlnaudo, 2008 Raabe et al., 2007 Vincent and Wegst, 2000). 

Cellulose and chitin are recognized as the first and the second most myriad of polysaccharides, respectively. Generally, chitin s resources are crustaceans like crab, prawn, lobster, and shrimp shell waste. Chitin is also widely distributed in marine-like invertebrates, insects, fungi, and yeast. Chitin is a long-chain polysaccharide composed of linear P-l,4-linked units of N-acetyl-D-glucosoamine (Rinaudo 2006). Chitosan is a biopolymer derived from chitin by deacetylation of acetyl groups (CO-CH3) (Figure 6.1). 

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