138 



WALTER JONES 



Guanine 



C 5 H 5 N r> () 



2-amino-6-oxy-purine 



Trie Acid 



C B II 4 N 4 3 

 2-6-8-trioxy-purine 



/OH 



P OH 



\OH 



P OH 



\BD 



Xantliinc 



C 5 H 4 N 4 2 



2-6-dioxy-pnrine 



/OH 



P OH 

 \H 



Adenine 



C 5 H 5 N 5 



6-amino-purine 



/H 

 P 

 \H 



Hypoxanthine 



C 5 H 4 N 4 



6-oxy-purinc 



/H 



P OH 



\H 



Guanine and adenine are referred to collectively as the amino-ptirines ; 

 xanthine and hypoxanthine as their corresponding oxy-purines. The 

 amino-purines may easily be converted into the oxy-purines by a deamin- 

 izing agent (nitrous acid). 



C 5 H 3 N 4 (NH 2 )+H 2 



adenine 



C 5 H 3 N 4 (OH)+NH 3 (Kossel ($, 1886) 



liypoxanthine 



C 5 II,N 4 O(NH 2 )+H 2 O = C 5 H 3 N 4 O(OH)+NH 3 (Strecker, 1858) 



guanine xanthine 



and it will be seen that these transformations are actually brought about 

 by deaminizing ferments present in the tissues. But guanine and adenine 

 cannot be directly converted into one another. The one has its ammo- 

 group in position two ; the other, in position six. 



NH N 



N N 





By oxidation, liypoxanthine could conceivably be changed into xanthim 

 C 5 H 4 N 4 + O = C 5 H 4 N 4 2 



