ABSENCE OF URICASE IN HUMAN TISSUE 161 



takes place with great intensity in the pulp of mam- 

 malian tissues. (It takes place apparently in other verte- 

 brates as well ; it is said that the liver of the ray is from 

 this standpoint more capable than any other vertebrate 

 tissue.) 33 There have been a number of attempts to isolate 

 an actual ferment, "uricase" (as far as it is possible to 

 speak of isolation in case of enzymes). 34 Wiechowski here 

 made the important discovery that living excised human tis- 

 sues are unable to break down uric acid under conditions in 

 which the tissues of lower mammals prove efficient, and that 

 the former therefore must be regarded as not conforming to 

 the usual rule. This has been confirmed from so many 

 sources 35 that there can be no doubt as to its correctness. 36 

 The objection raised that invariably a preuricase is present 

 but is prevented from manifesting itself because of the an- 

 tagonism of inhibiting substances can scarcely be accepted, 

 if for no other reason than that other ferments which are 

 active against purins, as xanthinoxydase and guanase, are 

 found without any difficulty in the human tissues. "If," 

 says Wiechowski, 37 " as is amply confirmed by all observers, 

 human tissues build up uric acid with ease from guanin and 

 xanthin but do not catabolize the substance thus formed, in 

 contrast to animal tissues, which oxidize the uric acid 

 further into allantoin, it seems to me the assembling of these 



83 V. Scaffidi (Zool. Station, Naples), Biochem. Zeitschr., 18, 506, 1909; 

 25, 296, 411, 415, 1910. 



M W. Wiechowski and W. Wiener (J. Pohl's Lab., Prague), Hofmeister's 

 Beitr., 9, 247, 1907; F. Battelli and L. Stern (Geneva), Biochem. Zeitschr., 19, 

 219, 1909; G. Galeotti (Naples), ibid., 30, 374, 1911. 



35 Battelli and Stern, Miller and Jones, J. G. Wells and H. J. Corper, cited 

 by Wiechowski, Biochem. Zeitschr., 25, 434, 1910. 



86 It would probably be going too far to deny entirely all possibility of a 

 uricolysis in human tissues, as there have been positive findings also in this 

 direction, as those of W. Pf eiffer, Croftan and Schittenhelm. Consult in refer- 

 ence to the physiological importance of the subject: W. Wiechowski, Arch. f. 

 exper. Pathol., 60, 199-200, 1907. " I believe that I am in position to conclude 

 with a fair certainty," says Wiechowski, " that in carefully prepared experi- 

 ment-conditions in which living excised animal tissues oxidize uric acid vigor- 

 ously, human tissues are practically inactive." 



" W. Wiechowski, Biochem. Zeitschr., 25, 436, 1900. 

 11 



