Polysaccharide (redirected from Polysaccharides)

polysaccharide: see carbohydrate.

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polysaccharide

Any of a large class of long-chain sugars composed of monosaccharides. Because the chains may be unbranched or branched and the monosaccharides may be of one, two, or occasionally more kinds, polysaccharides can be categorized in various ways. Cellulose, starch, glycogen, and dextran are all polysaccharides of glucose, with different configurations. Pectins are composed of a galactose derivative, chitin of a glucose derivative. Connective tissues, joint fluid, and cartilage contain two-component polysaccharides, including heparin. See also oligosaccharide.

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Polysaccharide

A class of high-molecular-weight carbohydrates, colloidal complexes, which break down on hydrolysis to monosaccharides containing five or six carbon atoms. The polysaccharides are considered to be polymers in which monosaccharides have been glycosidically joined with the elimination of water. A polysaccharide consisting of hexose mono-saccharide units may be represented by the reaction below.

The term polysaccharide is limited to those polymers which contain 10 or more monosaccharide residues. Polysaccharides such as starch, glycogen, and dextran consist of several thousand d -glucose units. Polymers of relatively low molecular weight, consisting of two to nine monosaccharide residues, are referred to as oligosaccharides. See Dextran, Glucose, Glycogen, Monosaccharide, Starch

Polysaccharides are often classified on the basis of the number of monosaccharide types present in the molecule. Polysaccharides, such as cellulose or starch, that produce only one monosaccharide type ( d -glucose) on complete hydrolysis are termed homopolysaccharides. On the other hand, polysaccharides, such as hyaluronic acid, which produce on hydrolysis more than one monosaccharide type (N-acetylglucosamine and d -glucuronic acid) are named heteropolysaccharides. See Carbohydrate