THE CHEMISTRY OF URIC ACID 619 



N=CH 



I I 

 HC C-NH 



II II X 



CH 



N-C-N 



Purine 



The derivatives of purine are described by stating to which atom 

 of tlie purine nucleus the combining groups are attached. Thus, 

 adenine is referred to as 6-aniino-purine, and therefore has the follow- 

 ing formula : 



N=C-NH2 



I I 



HC C— NH 



II II r^" 

 N-C-N 



Adenine (6-amino-purine) 



Other important members of this group of "purine bodies,*' (also 

 called xunthine bodies, alloxuric bodies, and nuclein bodies) are built 

 up about the purine nucleus as shown below : 



HN-C=0 HN-C=0 



II I I 



H2N.C C-NH 0=C C-NH 



II II >^» i II >^"- 



N-C-N HN-C-N 



Guanine Xanthine 



(2-aniinoUoxypurine) (2, 6-dioxypurine) 



HN-C=0 HN-C=0 



II II 



HC C-NH 0=C C-NH 



II II ^^" i II /*^=^- 



N-C-N HN-C-i^H 



Hvpoxanthine Uric acid 



(6-oxypurine) (2-6-8trioxypurine) 



H3C-N-C=0 H>J=C=0 



I I .CHa I I CH3 



o=c c-n/ o=c C-N/ 



! II ^cH ! II >^" 



H3C-N-C-N H3C-N-C-N 



Caffeine Theobromine 



(1-3-7 trimethyl-2-6 dioxypurine) (3-7-dimethyl, 2-ti di.ixypurine) 



As shown by their structural formula?, the purimidinrs present in 

 the nucleic acids are also closely related to the ])urines, viz: 



N — CH X — C — NH= HN — C = HX — Cc=.0 



HO CH = C CH = C CH 0<=.C C — CH» 



N = CH HN^ — CH TIN- — CH HN — CH 



Pvrimidine Cvtosine Uracil Thymine 



(2-oxy. 6-animo- (2-6-dioxy- (5-methyl. 2-6-dioxy- 



pyrimidine) pyrimidine) pyrimidine). 



