158 PHYSIOLOGY OF PURIN METABOLISM 



series, p. 113, Chemistry of the Tissues) or of a derivative 



C N x 



of the imidazol nucleus, I ^>C , histidin, 24 into the purin 



N C 

 nucleus, C C N v in which both the former nuclei are, 



VU> C> 



so to say, included. 



Allantoin as an End-product of Mammalian Purin Me- 

 tabolism. We come now to the most abstruse and debated 

 portion of the uric acid problem, that of uric acid destruction 

 in the body, uricolysis. For the past decade, in spite of all the 

 study devoted to it, this problem has remained fixed, un- 

 doubtedly for the reason, at present easily appreciable, that 

 the dominating position which is occupied by allantoin in the 

 nuclein metabolism in mammals was entirely overlooked. 

 The ignorance which previously prevailed upon the general 

 subject first began to lessen when Wilhelm Wiechowski con- 

 tributed to metabolic investigation an exact method of de- 

 termining allantoin and took up in definitive manner the 

 problem of uric acid destruction in a series of very carefully 

 conducted studies. 25 



After it became known from repeated investigations 26 

 that living excised tissues of mammals are capable of de- 

 stroying uric acid, Wiechowski proved that it is completely 

 oxidized in the process into allantoin without undergoing 

 further change : 



URIC ACID ALLANTOIN 



NH CO NH 2 



CO C NH, > CO CO NH V 



\ II >CO \ >CO. 



NH-C-NH/ HN-CH-NH/ 



84 E. Abderhalden, H. Einbeck and J. Schmid, Zeitschr. f. physiol. Chem., 

 68, 395, 1911. 



25 W. Wiechowski (J. Pohl's Lab., Prague), Hofmeister's Beitr., 9, 247, 

 295, 1907; 11, 109, 1907; Arch. f. exper. Pathol., 60, 185, 1909; Biochem. 

 Zeitschr., 25, 431, 1910; cf. in this last the Literature upon Uricolysia. 



28 Stokvis, Chassevant and Richet, Ascoli, Jacoby, Schittenhelm, Burian, 

 Austin, Almagia, Wiener. Cf. H. M. Vernon, Ergebn. d. Physiol., 9, 168, 1910. 



