MACROMOLECULES 93 



2. Chondroitin sulphate 



This is the sulphuric ester of a polysaccharide whose main constituents 

 are D-glucuronic acid and N-acetylchondrosamine. The hyalin cartilage 

 of vertebrates is a compound of chondroitin sulphate and a protein, the 

 binding being between the -COOH and — SO3H groups of the chondroitin 

 sulphate and the -NHo groups of the protein. 



3. Mucoitin sulphate 



It is similar to the above compound except that chondrosamine is 

 replaced by D-glucosamine. It is present in many animal tissues. 



II. PROTEINS 



Proteins are macromolecules w^hich on hydrolysis yield a mkture of 

 amino acids. Whatever their origin, they are always made up of a selection 

 of the 20 amino acids described previously (p. 24). These acids are of the 

 L-configuration and joined together chiefly by peptide bonds. The various 

 properties of the proteins depend upon the number of amino acid residues 

 forming the peptide chain, on the nature of the amino acids, the order in 

 which they are assembled, the branching of their chains and on the con- 

 figuration of the folding which results from the free rotation of the parts of 

 the peptide chains about certain bonds. 



A. Classification 



Proteins are divided into two main types : fibrous proteins and soluble 

 or globular proteins. Most fibrous proteins are insoluble in aqueous sol- 

 vents. Although they do not crystallize, they contain crystalline regions. 

 They are formed from long molecules arranged more or less rectilinearly 



REFERENCES 



Evans, T. H. & Hibbert, H. (1946). Bacterial polysaccharides, Advanc. Carbohyd. 



Chem., 2, 204-234. 

 Greenwood, C. T. (1952). The size and shape of some polysaccharide molecules, 



Advanc. Carbohyd. Chem., 7, 290-332. 

 Kabal, E. a. (1956). Blood Group Substances. Academic Press, New York. 

 Manners, D. J. (1957). The molecular structxire of glycogens, Advanc. Carbohyd. 



Chem., 12, 262-298. 

 McIlroy, R. J. (1948). The Chemistry of Polysaccharides, Arnold, London. 

 Mori, T. (1953). Seaweed polysaccharides, Advanc. Carbohyd. Chem., 8, 316-350. 

 Pigman, W. (1951). The Carbohydrates. Academic Press, New York. 

 Stagey, M. (1946). The chemistry of mucopolysaccharides and mucoproteins, 



Advanc. Carbohyd. Chem., 2, 162-203. 



