THE PROTEINS 



49 



pyrimidin bases, especially cytosin. The following scheme shows the 

 relationship of nuclein : 



Nudeoprotein 

 (digested with pepsin) 



Nuclein (brown sediment decomposed 

 by acid alcohol) 



Peptone 

 (goes into solution) 



Acid melaprotein (in solution) Nucleic acid (white 



precipitate) heated in closed tube with HC1 



Purin bodies Carbohydrate Phosphoric acid 



adenin, guanin) (pentose or hexose) 



Pyrimidin bases 

 (especially cytosiu) 



The chief of the pyrimidin bases is cytosin amino-oxypyrimidin, 

 C 4 H-N 3 0, graphically expressed: 



HN CNH 



II II 

 00 CH 



N=CH 



Uracil is dioxypyrimidin, C 4 H 4 N 2 2 , 

 HN CO 



OC CH 



I II 

 HN CH 



| Thymin is methyl uracil, C 5 H 6 N 2 2 , 



HN CO 



00 C.CH 3 



I II 

 HN CH 



The Purin Bases are perhaps the most important cleavage 

 products of nucleoprotein, distinguishing it from phosphoprotoin, 

 which does not contain them. They are all compounds of the hypo- 

 thetical purin ring (see p. 38 ). 



The two immediate products of hydrolysis are adenin and guanin. 

 These are in close relationship with the b?,ses hypoxanthin and 

 xanthin and with uric acid. 



4 



