AUTODIGESTION OF NUCLEAR PROTEIDS 



435 



enzyme 'guanase.' This body is also present in the thymus and 

 suprarenal, but not in the spleen. As in autodigested spleen adenin 

 is converted into hypoxanthin in the absence of guanase, there must 

 be present a second ferment (adenase), which also occurs in the 

 thymus, the suprarenal, and the pancreas. 



To show the difference between the hydrolysing action of boiling 

 mineral acids, resulting always in the production of guanin and adenin, 

 and that produced by the autodigestion of nucleo-proteids, Jones and 

 Partridge have put the products of autolysis into tabular form : 



Jones and Partridge assume that both autodigestion and hydrolysis 

 originally liberate the same bases, but that subsequently the bases 

 undergo a further change as the result of special ferments which are 

 present in the autodigesting organs. 



Schittenhelm l was the first to establish the quantitative transition 

 of' the amino-purins : adenin and guanin into uric acid under the 

 influence of tissue ferments, and also to show that the purin-com- 

 pounds of thymus-nucleic acid were convertible into uric acid, and 

 that the uric-acid-forming oxydase of the spleen can be salted out 

 with ammonium sulphate. 



In a second paper, Schittenhelm 2 has thrown still further light on 

 the ferments of nuclear metabolism. By subjecting spleen-extract to 

 fractional precipitation, according to Jakoby's plan, 3 he found the 

 oxidising ferment to be thrown down in largest amounts by 66 per cent 

 saturated ammonium sulphate solutions. The precipitate obtained in 

 this way was suspended in water ; the mixture shaken for a half to 

 one hour and then dialysed in running water for six to eight days till 

 ammonia was no longer demonstrable. The filtered solution, of a 

 slightly yellowish brown colour, was very active, as at incubation 

 temperature it converted guanin quantitatively into uric acid, provided 

 air was passed through the solution containing the ferment and the 

 guanin, while if no air was passed through, guanin was converted 



1 A. Schittenhelm, Zeitsch.f.physioL Chem. 42. 251 (1904) (here the older literature). 

 - A. Schittenhelm, ibid. 43. 228 (1904). 

 3 Jakoby, ibid. 30. 135 (1900). 



