URIC ACID AND THE PURINE BODIES 639 



NueteicAcid (without the pyrimidine group) 



/ 

 tf 



(Action of nucleuses) 



d ' \ 



Guanine< L -(7) Guanosine A d en o sine (8) >Adenine 



euses) \ 



\ \ 



d en o sine 8 >Ad 



(4) (5) (6) 



(Action of deamvnizing enzymes') 



>Jr <V 



Xauthosine Inosine 



(9) (Action of hydrolysing enzymes) (10) 



- 

 Uric Acidf- ( 11 ) Xanthine < - ( 11 ) - Hypoxanthine 



(Action of xanthine oxidase) 



(Jones.) 



The next step in the disintegration process is that the amino group 

 is removed and the corresponding oxypurine is produced. To bring this 

 about, there exists a specific deaminizing enzyme for each of the above 

 amino compounds, and each enzyme is named according to the exact 

 amino purine upon which it acts; thus, guanase (3), guanosine-deaminase 

 (4), adenosine-deaminase (5), and adenase (6) have all been identified. 

 The free base may then be split off from the nucleosides by specific 

 hydrolyzing enzymes (1} (8) (9) (10). 



The joint action of these enzymes leads to the formation of oxypurines, 

 xanthine and hypoxanthine, which are oxidized to uric acid by xanthine- 

 oxidase (11). 



In man and the anthropoid apes uric acid is the end product of the 

 above changes, but in other mammals most of the uric acid is further 

 oxidized into allantoine. It has also been found, except in man and the 

 chimpanzee, that extracts of organs such as the liver, are capable of 

 decomposing uric acid into allantoine. The identification of these specific 

 enzymes is sought by a determination of the free amino-purine bases 

 and the phosphoric acid produced by allowing an aqueous extract of 

 the tissue in question to act on nucleic acid (of yeast)* at body tempera- 

 ture. Another portion of the digested mixture is then hydrolyzed by 

 means of boiling sulphuric acid and the constituents again determined. 

 From the results it is often possible to draw conclusions as to the exact 

 nature of the enzymes present. 



The most remarkable outcome of this work has been to show that 

 the distribution of the enzymes is not the same in the tissues and organs 

 of different animals. Very briefly, some of the most important results 

 that have so far been obtained are as follows: Gastric and pancreatic 

 juices do not contain a trace of any of the enzymes. Intestinal juice, 



'Yeast nucleic acid is used because it is less resistant to disintegration than thymic nucleic acid. 



