ii CHANGES DURING METABOLISM 111 



2. Imino-lytic ferments [including also the amino-lytic ferments 



acting on the ammo-groups of urea]. 

 The imino-lytic ferments are again subdivided into 



(1) Trypsin and erepsin, which separate the imide NH from the 

 neighbouring carbonyl CO, according to the general formula : 



CO NH C becomes COOH, NH 9 C ; 



(1) (2) (1) (2) 



or as in the case of arginin : 



CO NH CNH NH C becomes 



(1) (2) 



COOH, NH 2 CNH NH C ; 



(1) (2) 



NH 2 



(2) Arginase, which separates off urea or C0<^ from arginin. 



NH 2 



NH 2 . CNH . NH . C 3 H 6 . CHNH 2 . COOH + H 2 - 

 NH 2 . CO . NH 2 + NH 2 . C 3 H 6 . CHNH 2 . COOH. 



The changes induced by arginase in arginin are : proton (/3-clupeon) 

 -> arginin -> ornithin -> urea > amino-valerianic acid. The arginase 

 may be extracted from liver-substance with water or dilute acetic acid ; 

 it is also present in the mucous membrane of the dog's intestine, 

 and its, probably, universal occurrence explains why arginin is absent 

 amongst the products of autolysis. 1 



A second paper on arginase by Kossel and Dakin 2 shows that 

 ornithin remains attached to the albumin-molecule, while several or 

 all of the arginin-compounds are attacked in such a manner as to 

 liberate the urea-radical, or at least to become changed in some as 

 yet unknown manner. 3 



That arginase also occurs in the yeast has been shown by Shiga 4 

 working under Kossel. Shiga also found that arginase does not act 

 on guanidin, which is the mother-substance of arginin. 



There are, further, some enzymes which behave analogously to 

 putrefactive bacteria in splitting off the terminal carboxyl- group 

 (see p. 103), and which convert lysin and ornithin into cadaverin 

 and putrescin, and tyrosin into oxyphenylethylamin. Werigo 5 and 



1 Kutscher and Seemann, Zeitschr. f. physiol. Chem. 34. 114 (1901), and 35. 440 

 (1902). 



2 H. D. Dakin, Journ. of Physiol. 30. 84 (1903). 



3 A. Kossel and H. D. Dakin, Zeitschr. f. physiol. Cliem. 42. 181 (1904). 



4 K. Shiga, ibid. 42. 502 (1904). 



5 B. Werigo, Pflagers Arch.f. d. gesamte Physiol. 51. 362 (1892). 



