294 LECTURE XIII. 



The ferment which converts guanine into xanthine, and adenine into 

 hypoxanthine, is widely distributed. It is evidently found in all organs. 

 The oxidizing ferment, on the other hand, which finally produces the 

 uric acid, seems to be restricted to individual organs. It has been found 

 in the spleen, lungs, liver, intestine, muscles, and the kidneys of cattle. 

 Further investigations have disclosed the remarkable fact that the same 

 organs of different kinds of animals vary considerably in this respect, so 

 that a generalization of results obtained with different species of animals 

 is not permissible. Schittenhelm and Bendix l showed that the trans- 

 formation of purine bases into uric acid not only takes place in this way 

 in glass vessels, but also in the organism itself, by injecting guanine sub- 

 cutaneously and intravenously into a rabbit. They found a considerable 

 increase in the uric acid of the urine, and detected the presence there 

 of a purine base corresponding to xanthine, which is evidently to be 

 regarded as an intermediate product in the formation of uric acid from 

 guanine. 



Up to this point we have not mentioned an important fact which makes 

 it difficult to trace the quantitative relations in the production of uric 

 acid from the purine bases. There are ferments present in many tissues 

 of the animal organism which are capable of further decomposing the 

 uric acid formed. Schittenhelm calls them uricolytical ferments, in order 

 to indicate that we are dealing with an entirely different process from 

 that of the uric acid production. Such a ferment has been found in the 

 kidneys, liver, and muscles, and very probably also in bone marrow. 2 

 Schittenhelm has succeeded in isolating this ferment. It is evident that 

 if a destruction of uric acid takes place in the animal tissues, the old-time 

 conception that the amount of uric acid excreted is an index of the quan- 

 tity of uric acid formed in the organism, can no longer be accepted. An 

 increased excretion of uric acid in the urine may, of course, be due to a 

 greater production thereof; it may, however, also indicate a lessened 

 destruction. 



The question now arises, What are the degradation products of uric acid 

 when a decomposition sets in? We can at once answer that we do not 

 know definitely. Hugo Wiener 3 has practically proved that glycocoll 

 is produced from uric acid when administered to a rabbit. He found 

 that the reserve supply of glycocoll in this animal was fairly constant. 

 An increase was noted in the amount of glycocoll excreted after the injec- 

 tion of uric acid. This increase could be checked by administering ben- 

 zoic acid, in which case hippuric acid was formed. Wiener has also showp 



1 Z. physiol. Chem. 43, 365 (1905). 



3 Cf. also Hugo Wiener, Arch, exper. Path. Pharm. 42, 375 (1899); also Zentr. 

 Physiol. 18, 690 (1905). 



3 Arch, exper. Path. Pharm. 40, 313 (1897). 



