; RIC KCID AND 'illi PI ki\i B0D1 



Nucleic Acid (without the pyrimidine group) 



(1) (1) ^(2) 



(Action of nucleases) 



sL \ 



Guanine *-(7) Guanosine Adenosine (8)— > Adenine 



(4) (5) 



(Action of dcaminizing enzymes) 



Xacthosine Inosine 



(9) (Action of hydrolyzing enzymes) (10) 



UricAeid<— (11) Xanthine < -(H)— »• Hypoxanthine 



(Action of xanthine oxidase) 



(Jones.) 



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

 is removed and tin- corresponding oxypurine is produced. To bring this 

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

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

 amino purine upon which it acts; thus, guanase '■'< . guanosine-deamii 

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

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

 lunlrnlj/zitiif , h: ames (7 - '• (10). 



The joint action of these enzymes leads to the formation of oxypurii 

 xanthine and hypoxanthine, which are oxidized to uric acid by xant) 

 oxidase (11). 



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

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



oxidized into allantoine. It has also 1 u found, except in man and the 



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

 decomposing uric acid into allantoine. The identification of th< - - scific 

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

 and the phosphoric acid produced by allowing an aqueous extract 

 the tissue iii question to act on nucleic acid of yeasl * 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 th< 

 nature of the enzymes present. 



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



distribution of tht enzyme* - not ta< sonn In vans 



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



that have so far been obtained are as follows trie and pancreatic 



juices do not contain a trace of any of the enzymes. Entestinal jui 



•Yeast nucleic ai ill is uscil because it is Ir- n than thymic nucleic . 



