URIC ACID AND THE PURINE BODIES 



669 



Purinc itself has the following structural formula : 



IN CG H 



H2-C 



C5 - 



NH7 



C8-H 



-C4-N9 



(For convenience of description the atoms in purine are numbered as shown.) 



HN-C=O 



H- C 



I 



C- 



NH 



I. 



\ 



HN - C = O 

 O = C C-NH 



C-H 



-C- 



(hypoxanthine) 



II. 



\ 



C-H 



N--C- N 



(6-oxypurine) 

 = C-NH 2 



(xan thine) (2-6-oxypurine) 



H- C C-NH 



HN-C=0 



I I 

 H 2 N = C C-NH 



-C- N 



/ 



C-H 



\ 



C-H 



N-C- N 



(adenine) (6-amino-purine) (guanine) (2-amino-6-oxypurine) 

 HN-CO 

 OC C-NH 



\ 



CO 



[N- C -NH 



Uric acid (2-6-8-trioxypurine) 



The substances with which the purine bases are most closely related are the pyri- 

 midine bases. Three of these are known: 



thymine (NH-CO 



I ! 



CO C.CH 3 



cytosine ( N = C-NH 2 



I 

 CO CH 



NH-CH) ; 



and uracil (NH-CO 



I ! 

 CO CH 



NH-CH). 



From an examination of the structural formulas, it will be seen that they are more 

 or less related to purine (having one of the urea radicles omitted), although it can 

 scarcely be doubted that they exist as separate constituents of the nucleic acid group 

 in the animal body, and are not derived from purine. They are primary products. 



The Chemical Nature of the Substances in Which Purine and 

 Pyrimidine Bases Exist in the Animal Body. In general it may be said 

 that the amino purines adenine and guanine together with the 

 pyrimldine bases thymine and cytosine occur combined with phos- 

 phoric acid and a carbohydrate in the various nucleic acids, each of which 



