CONVERSION OF ADENIN INTO URIC ACID 149 



The recognition of this relation had its beginning in the 

 classical studies of Horbaczewski in 1889 upon the formation 

 of uric acid in the splenic pulp ; and slowly crystallized into 

 its present form from a great number of investigations, 

 among which those of Kossel and his school, and of W. 

 Spitzer, H. Wiener, A. Schittenhelm, N. Jones, R. Burian, 

 L. B. Mendel and their collaborators stand out prominently. 1 



Conversion of Adenin and Guanin into Uric Acid. 

 As previously stated (Vol. I of this series, p. 112, Chem- 

 istry of the Tissues), the physiological relation between the 

 two bases in the nucleinic acid molecule, adenin and guanin, 

 with hypoxanthin, xanthin and uric acid may be expressed 

 by the following schema : 



ADENIN (CbHsNfi) GUANIN (C6H 6 N 6 O) 



N-C=NH N-C=O 



C C-Nv NH=C C-Nv 



N-C-N/ N-C-N/ 



HYPOXANTHIN (C 6 H4N 4 O) XANTHIN (CsS^N^) URIC ACID (C 6 H4N 4 Oj) 



N-O=O N-C=O N-C=O 



C C N x >. 0=C C-N X ^ 0=C C-N 



\ I >C \ I / C \ I 



N-C-N / N-C-N / N-C-N 



The transformation of adenin and guanin into hypoxan- 

 thin and xanthin by replacement of their NH group by an 

 atom of oxygen is ascribed to ' ' deamidases ' ' whichmust effect 

 changes of the type indicated in the formula : E : NH + 

 H 2 = R: + NH 3 . Jones recognizes two of these 

 enzymes, " adenase" and " guanas e." In the conversion 

 of hypoxanthin into xanthin and the latter into uric acid, 

 oxidizing ferments known as " xanthoxydases" are 

 concerned. 



1 Literature upon the Formation of Uric Acid from the Nucleins: H. 

 Wiener, Ergebn. d. Physiol., 1, 575-606, 1902 ; F. Samuely, Handb. d. Biochem., 

 1, 565-566, 1909; A. Ellinger, ibid.,3', 575-576, 1910; A. Schittenhelm, ibid., 

 4', 490-514, 519-531, 1910; C. Oppenheimer, Die Fermente, 3d ed., 5, 166-170, 

 370-372, 1910; H. M. Vernon, Ergebn. d. Physiol., 9, 162-167, 1910. 



