92 UNITY AND DIVERSITY IN BIOCHEMISTRY 



2. Bacterial polysaccharides 



(a) Pneumococcal — These polysaccharides control the immunological 

 type specificity of the pneumococci by their presence in the bacterial 

 capsule. Their constituents are D-glucose, D-glucuronic acid, aldobionic 

 acids and amino sugars. The proportions of each vary from one type to 

 another and certain constituents may be missing. 



Examples of constituents which have been identified : 

 Type I. Galacturonic acid and an acetylhexosamine. 

 Type II. D-Glucose, D-glucuronic acid, L-rhamnose. 

 Type III. D-Glucose and D-glucuronic acid. 

 Type IV. N-Acetylhexosamine, D-glucose. 



(b) Of other microorganisms — Mucopolysaccharides of numerous micro- 

 organisms have recently been studied. The luteose of Pencillium luteum, 

 for example, is a poly-D-glucose in which the glucoside bonds are of the 

 1:6-/3 type. The complex antigen has been isolated from the typhus 

 bacterium, Eberthella typhosa, it is a complex chain of sixty hexose units, 

 with 50% of D-glucose, 25% of D-mannose and 25% of D-galactose. 

 Tuberculin, the medium from the concentrated culture of Mycobacterium 

 tuberculosis, contains a polysaccharide in which there is D-arabinose, d- 

 mannose and D-galactose together with a little D-glucosamine. In the 

 mucopolysaccharide of Corytiebacterium diptheriae there are D-galactose, 

 amino sugars and pentoses. 



Several mucopolysaccharides have been isolated from Penicillium 

 charlesii cultivated on D-glucose. Mannocarolose, one of these products, is 

 a mannan having a straight chain with 1:6 linkages, whilst galactocarolose, 

 from the same source, is a straight chain galactan containing 1:5 linkages. 



3. Blood group polysaccharides 



These are mostly polysaccharide in nature, but their molecules also 

 contain such substances as amino acids. 



The substance of Group A, a branched molecule, contains L-fucose, 

 D-glucosamine, D-galactose and D-mannose. Very little is yet known about 

 the polysaccharides of the other blood groups. 



C. Polysaccharide Sulphuric Esters, or Mucoitinsulphates 



1. Heparin 



Heparin is the sulphuric ester of a polysaccharide containing d- 

 glucuronic acid and D-glucosamine. 



