NUCLEIC ACIDS AND NUCLEOPROTEINS 



127 



The fate of the amino purines in the animal body is of considerable 

 interest. It has been shown that certain tissues contain enzymes 

 which transform these amino purines first to corresponding oxypurines 

 known as hypoxanthine and xanthine and finally to uric acid. It is 

 probable that different enzymes enter into the various steps of these 

 transformations leading to the formation of uric acid. Still another 

 enzyme carries the oxidation further with the formation of the com- 

 pound allantoin. This enzyme is known as uricase. The purine 

 enzymes are widely distributed in tissues. The transformations 

 brought about are indicated in the following diagrams. 



N=CNH 2 



HC C NH +H 2 O NH 3 - 



\^ Adenase 



CH 



N C N 



Adenine 

 6-amino purine 



HN CO 



HC C NH 



CH 



N C N 



Hypoxanthine 

 6-oxypurine 



+0 



Hypoxanthine 

 oxidase 



HN CO 

 H 2 N-C C NH 



HN CO 



I I 

 OC C NH 



CH +H 2 NH 3 ^ 



// Guanase 



N C N 'HN C N 



Guanine 

 2-amino-6-oxypurine 



CH 



Xanthine 

 2-6-dioxypurine 



Xanthine 

 oxidase 



NH 2 



CO CO NH O 



\ Uricase 



CO 



NH CH NH 



Allantcin 



HN CO 



I 

 OC C NH 



CO 



HN C NH 



Uric acid 

 2-6-8-trioxypurine 



