232 MACROMOLECULAR COMPLEXES 



Polysaccharide-protein complexes are beginning to acquire sig- 

 nificance both in plant and in animal physiology; whether the struc- 

 tural component is dominantlv protein or dominantly polysaccharide, 

 it may well be that the same principles are involved. It is proposed 

 here, therefore, to examine evidence from both fields. 



Although the principal structural components of animal tissues 

 are undoubtedly protein, there are many recorded observations 

 which show that polysaccharides of several kinds are involved, some- 

 times in considerable abundance. An outstanding case is the de- 

 velopment of tunicin, indistinguishable from plant cellulose, in the 

 tunica of sea squirts, but many cases of polvsaccharide association 

 with proteins have been reported. These are often acid polysac- 

 charides, the acidic group being represented by hvaluronic acid, 

 chondroitin sulfuric acid, and some partially sulfated variants of 

 these two. Some, however, are devoid of hexosamine or uronic acids. 

 Grassman and Schleich (1935) identified glucose and galactose in 

 hydrolysates of skin extracts, an observation confirmed by Gross 

 et al. (1952), who added mannose as a constituent sugar. More 

 recently, other polysaccharides rich in glucose have been reported 

 from mammalian sources. Dische and Borenfreund (1954) claim to 

 have demonstrated the presence in lens capsule of a polysaccharide 

 containing galactose and glucose in the ratio 3:2, and Dische and 

 Zelemenis ( 1955 ) found a similar polysaccharide in the vitreous 

 body. Again, polysaccharide material containing galactose, man- 

 nose, and glucose in the ratio 6:1:2 has been isolated from kidney 

 ( Dohlman and Balazs, 1955 ) . It may be, however, that these repre- 

 sent mixtures of polysaccharides, since Dische et al. ( 1958 ) have 

 found the composition of similar polysaccharides in the bones of 

 cattle to vary with the age of the animal. Indeed, a polysaccharide 

 fraction in abdominal subcutaneous tissue has been shown to con- 

 sist of pure galactans and pure mannans (Consden and Bird, 1954). 

 In all these cases, the polysaccharide is associated with a protein 

 which is, in every case, collagen. There is no direct evidence that 

 glucans alone exist in any of these tissues, but the hexasaccharide 

 isolated from umbilical cord by Akiya and Tomoda (1955) and 

 considered by them to consist of /3-D-glucose residues joined bv 1-4 

 links, might be a precursor, or a degradation product, of cellulose. 



There is some evidence that these polvsaccharides pla\' an im- 

 portant role in the stabilization of the associated collagen. Jackson 



