436 CHEMISTRY OF THE PROTEIDS CHAP. 



into xanthin. Therefore guanin is converted through the xanthin 

 stage into uric acid. The 2-amino, 6, 8-dioxy-purin, which might 

 have given rise to uric acid, was absent. The spleen is thus capable 

 of reacting, contrary to the statement of Jones, in the same way as 

 the thymus, the pancreas, and the suprarenal, and also the liver, 

 lung, and muscle, while apparently no uric acid formation out of 

 guanin occurs in the thymus, intestine, blood, and kidney. 



As guanin is converted into xanthin in the thymus and the kidney, 

 there must be present two ferments, one of which is a desaminating 

 one, converting guanin into xanthin and adenin into hypoxanthin, 

 while the second ferment is an oxidising one, changing hypoxanthin 

 into xanthin and xanthin into uric acid. 



While the desaminating ferment is distributed widely over the 

 body, the oxidising ferment seems to be more restricted in its 

 distribution. 



As the desaminating ferment acts on both guanin and adenin, 

 Schittenhelm believes the terms ' guanase ' and ' adenase ' to be 

 superfluous. But as the spleen ferment, which converts guanin into 

 xanthin and xanthin into uric acid, is unable to dissociate a-nucleic 

 acid, and thus to liberate the purin-bases contained in it and then 

 to change them into uric acid, there must be present a third ferment, 

 the ' nuclease,' which can split up nucleic acid. 



A fourth ferment capable of disintegrating uric acid, suggested 

 by the destruction of uric acid in the tissues (Wiener l and Ascoli 2 ), 

 Schittenhelm has also isolated. It is most abundant in the kidney, 

 but is also present in the liver, muscle, and perhaps bone-marrow. 



Walter Jones in his last paper 3 has pointed out, in collaboration 

 with Winternitz, against Schittenhelm, that watery infusions of spleen 

 do not alter guanin, and that therefore they do not contain guanase, 

 and that spleen infusion by autodigestion quickly gives rise to hypo- 

 xanthin, which by prolonged digestion is gradually converted into 

 xanthin. As further, guanin is not altered by an infusion of spleen, 

 while adenin added to spleen infusion is quickly changed into hypo- 

 xanthin, it follows that an oxydase must be present which converts 

 adenin into xanthin. On autodigesting liver they found guanin, 

 considerable quantities of xanthin, and traces of hypoxanthin. The 

 presence of guanin in autodigested liver, as well as the fact that 

 guanin added to autodigesting liver remains unaltered, shows again the 

 absence of guanase. Adenin is, however, quickly changed into xanthin 



1 H. Wiener, Arch. f. exp. PathoL u. Pharmak. 42. 375 (1899). 



2 G. Ascoli, Pflugers Arch. 72. 340 (1898). 

 3 W. Jones and M. 0. Winternitz, Zeitschr. f. physiol. Chem. 44. 1 (1905). 



