504 URIC-ACID METABOLISM AND GOUT 



body, purin, the nucleus is called the "purin nucleus" The 

 structural relations of the better-known " purin bodies " to this 

 purin nucleus and to each other is clearly shown by their struc- 

 tural formulae, as given below : 



The atoms in the " purin nucleus " are arranged as follows : 





 0( 6 ) 



N 



( 3 ) Cu) N( 9 ) 



To each atom has been given a number, as shown, for the pur- 

 pose of facilitating reference to the location of various atoms 

 and groups that are attached to this nucleus. The structure of 

 purin itself is as shown below : 1 



N = CH 

 HO NH 



-C-N 



Purin 



The derivatives of purin are described by stating to which 

 atom of the purin nucleus the combining groups are attached. 

 Thus, adenin is referred to as 6-amino-purin, and therefore has 

 the following formula : 



N=C-NH 2 

 HO NH 



i 



-iUf 



Adenin (6-amino-purin) 



Other important members of this group of "purin bodies," 

 (also called xanthin bodies, alloxuric bodies, and nuelein bodies) 

 are built up about the purin nucleus as shown below : 



N C = O HN C = O 



H 2 N.C NH O = C NH 



Guanin Xanthin 



(2-amino-6-oxypurin) (2, 6-dioxypurin) 



1 In these formulae the symbols of the atoms forming the purin nucleus 

 are in heavy type. 



