FORMATION OF URIC ACID. 703 



of different kinds act together. By means of the two deamidizing enzymes 

 adenase and guanase, the adenine and guanine are transformed into 

 hypoxanthine and xanthine respectively, and from the latter by means 

 of an oxidizing enzyme, called xanthine oxidase by BURIAN, the uric 

 acid is formed. In the formation of uric acid from the nucleoproteins 

 we must admit of a gradual decomposition of these by the aid of different 

 enzymes, proteases, nucleases and deamidases. The deamidases seem 

 to be present in most organs, and we have numerous investigations upon 

 their distribution, especially those of JONES and SCHITTENHELM and 

 his collaborators. 1 The distribution is not the same in all animals and 

 the reports regarding it are unfortunately conflicting (SCHITTENHELM, 

 JONES and MILLER). We must exercise the greatest caution in drawing 

 conclusions as to the occurrence of these enzymes, and from experiments 

 made with the extracts of organs, because it seems as if also other 

 unknown factors must be considered in the formation of uric acid. 

 Thus JONES has with ROHDE 2 shown that in rats the organs do not con- 

 tain any xanthine oxidase, and that nevertheless the urine of this animal 

 contains uric acid. On the other hand deamidases occur in the organs 

 of monkeys (and xanthine oxidase in the liver) but the urine does not 

 contain any uric acid and only traces of allantoin ( WELLS) . 3 The pos- 

 sibility of a uric acid formation in man and mammalia in another way 

 from the enzymotic destruction of the purines cannot, for several reasons, 

 be denied. 



In birds the conditions are different, v. MACH 4 has shown that in 

 the bird family a part of the uric acid may be formed from the purine 

 bodies. The chief quantity of uric acid, however, is undoubtedly formed 

 in birds by synthesis. 



The formation of uric acid in birds is increased by the administra- 

 tion of ammonium salts (v. SCHRODER), and urea acts in a similar 

 manner (MEYER and JAFFE). MINKOWSKI observed, in geese with 

 extirpated livers, a very significant decrease in the elimination of uric 

 acid, while the elimination of ammonia was increased to a corresponding 

 degree. This indicates a participation of ammonia in the formation 

 of uric acid in the organism of birds; and as MINKOWSKI has also found, 

 after the extirpation of the liver, that considerable amounts of lactic 

 acid occur in the urine, it is probable that the uric acid in birds is pro- 

 duced in the liver by synthesis, perhaps from lactic acid and ammonia; 



1 See footnote 4, page 703. 



2 Jones, Zeitschr. f . physiol. Chem., 60, with Alice Rohde, Journ. of biol. Chem., 7; 

 see also Voegtlin and Jones, Zeitschr. f. physiol. Chem., 66. 



3 Journ. of biol. Chem., 7. 



4 Arch. f. exp. Path. u. Pharm., 24. 



