CHAPTER 19: POLYSACCHARIDES AND CARBOHYDRATE STRUCTURES

Macromolecules with molecular weights exceeding one million that are found in nature. Their biologic activity is determined by the sequence and three-dimensional structure of their various monosaccharides.

Polysaccharides

A polysaccharide consisting of numerous a-1,4 linked D-glucose molecules, with branching points occurring via a-1,6 linkages. It is the form in which animal tissues store glucose.

Glycogen

The glucose store of plants, found in cereals, potatoes, legumes, and other vegetables. It consists of amylose (nonbranched) and amylopectin (branched) molecules.

Starch

An insoluble polysaccharide consisting of long, non-branched b-1,4 linked glucose units. It is the most abundant organic compound on earth and is nondigestible by mammalian enzymes.

Cellulose

A structural polysaccharide found in the exoskeletons of invertebrates. It consists of N-acetyl-D-glucosamine units joined by b-1,4 glycosidic linkages.

Chitin

A fructose polymer found in tubers and roots of certain plants. It is soluble in warm water and is used to evaluate kidney function.

Inulin

Chains of complex carbohydrates characterized by their content of amino sugars and uronic acids. When attached to a protein, they form proteoglycans and are associated with structural elements of tissues.

Glycosaminoglycans

Compounds derived from carbohydrates where the carbonyl group is reduced to a hydroxyl group. Examples include glycerol and inositol.

Sugar alcohols

Compounds involved with structural polysaccharides and clearing metabolites from the body. Uronic acid anions, such as glucuronate, result from the oxidation of UDP-glucose.

Sugar acids

Sugars that lack one hydroxyl group. An important example is 2-deoxyribose,

Deoxysugars