ii SECONDARY DISSOCIATION-PRODUCTS 99 



oxidative and des-aminative properties. Saitos, 1 however, has shown 

 that the des-amination of tyrosin cannot be the function of the 

 ferment tyrosinase, because the ammonia- and tyrosinase-reactions do 

 not run parallel with one another. This view is shared by Shibata.- 

 The only other enzyme known in plants is the urease, or urea-splitting 

 enzyme. 



In animals special enzymes seem to be present. Loewi 3 has 

 described a urea-forming ferment in the liver, and has shown that 

 glycocoll and leucin give rise to an alcohol-ether soluble body with an 

 easily dissociable amid-radical. Jakoby 4 found that liver-juice pre- 

 served under toluol showed a marked increase of the ammonia- 

 nitrogen (amid-nitrogen), at the expense of the amino- acid -nitrogen 

 (see p. 77). He failed, however, in getting the liver-juice to act 

 on glycocoll. 



That tryptic digestion splits off ammonia from the albumin-mole- 

 cule has been shown by Hirschler, 5 Kutscher, 6 and others. Pepsin 

 acts similarly on albumin according to Zunz. 7 But that neither 

 trypsin nor pepsin have any action on ammo-acids has been shown 

 by Gulewitsch. 8 His observations are confirmed by Schwarzschild, 9 

 who found that trypsin was unable to split off ammonia from 

 asparagin, acetamide, urea, biuret, oxamide, benzamide, glycinamide, 

 etc. But there is one exception to this rule, namely, the glycin-base 

 of Curtius, or hexaglycyl-glycin-ethylester, as it does give off 

 ammonia when acted upon by trypsin, while with pepsin it does not 

 react at all. 



Schmiedeberg 10 has shown that liver-pulp can convert hippuric 

 acid into glycocoll and benzoic acid, and Gonnermann finds that 

 acetamide, oxamide, benzamide, etc., mixed with liver-pulp, containing 

 1 per cent of sodium-fluoride as an antiseptic, are split up in some 

 cases. 



Shibata 2 has shown that in addition to the uro-bacteria, urea is 

 also broken up by Aspergillus niger ; and further, that this mould 

 has some action on biuret, a very slight action on urethan, and 



1 K. Saitos, Botanical Magazine (Tokio), No. 201, Nov. 1903. 



2 K. Shibata, Hofmeisters Beitrage, 5. 384 (1904). 



3 0. Loewi, Zeitschr. f. physiol. Chem. 25. 511 (1898). 



4 M. Jakoby, ibid. 30. 149 (1900). 



5 A. Hirschler, ibid. 1O. 302 (1886). 



6 E. Kutscher, Endprodukte der Trypsinverdauung, 1899 (Dissertation). 



7 E. Zunz, Zeitschr. f. physiol. Chem. 28. 132 (1899). 



8 Wl. Gulewitsch, ibid. 27. 540 (1899). 



9 M. Schwarzscliild, Hofmeisters Beitrdge, 4. 155 (1904). 



10 0. Schmiedeberg, Arch. f. experim. Patliol. u. Pharm. 14. 288 (1881). 



