138 



WALTER JOXES 



Uric Acid 

 2-0-S-tno\v-puriue 



/OH 



F OH 



\OII 



< 



Guanine 



C 5 II, > K,0 



2-amino-ti-oxy-purine 



P OH 

 \H 



Xantliinc 



C r) H 4 ]\ T 4 O 2 



2-G-dioxy-purine 



/OH 

 P OH 

 \H 



Adeninc 



CWST, 



6-amino-purine 



P NH 2 

 \H 



Hypoxanthinc 



C 5 H 4 IT 4 



6-oxy-purinc 



P OH 

 \H 



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

 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 B H. 1 3S T 4 (NH 2 r+H 2 = C 5 H 3 N 4 (OH)+NH 3 (Kossel (c), 1886) 



adenine hypoxanthine 



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



guanine 



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 amino- 

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



By oxidation, hypoxanthine could conceivably be changed into xanthine 

 C.H- 4 N 4 +0 == C 5 H 4 A T 4 2 



