62 



NUCLEOPROTEINS, NUCLEINS, NUCLEIC ACIDS. [CH. III. 



The purine bases are of especial interest in connection 

 with the origin of uric acid. 



(6) 

 CH 



(i) 



(7) 

 Purine is C 5 H 4 N 4 or (2) HC ($)C - NH 



(3) N 



;CH(8) 



(4) (9) 



The figures in brackets are used for indicating the position 

 of substitution groups. The chief purines of physiological 

 interest have either the (2), (6), or (8) H atoms replaced, so 

 we can write purine as 



H...(6) or simply 



H 

 H 

 H 



Adenine is 6-amino-purine, PC NH 2 or 



\H 



N=C.NH 2 

 HC C NH 



I! II 



N C N 



CH 



By the action of a deaminising enzyme, adenase, it is con 

 verted to hypoxanthine, or 6-oxy-purine, 



OH 



Guanine is 2-amino-6 oxy-purme, 



OH 





