156 LECTURE VIII. 



The position of the carboxyl group had not been determined. Emil 

 Fischer l finally cleared up the constitution of ornithine by its synthesis. 

 By this it was definitely determined that ornithine was an a-, d-, diamino- 

 valeric acid. 



Thus one of the decomposition products of arginine, the ornithine, was 

 identified. It was next to be decided in what form the urea which was 

 obtained from arginine occurred in it. E. Schulze and E. Winterstein 

 suggested that a guanidine derivative was united to the ornithine. The 

 separation of urea and ornithine from such a compound would proceed in 

 the following manner: 



NH 2 NH 2 



[ 2 Cl 



NH = C NH CH 2 CH 2 CH 2 CH COOH 4- H 2 O 



it 



^* v ' 



Arginine 

 NH 2 NH 2 NH 2 



C=O + CH 2 CH 2 CH 2 CH COOH 

 X NH 2 



Urea Ornithine 



Schulze and Winterstein finally succeeded in synthesizing arginine from 

 ornithine and cyanamide, thereby establishing the constitution of arginine. 



NH 2 NH 2 



Hjj CHz CHa CH COOH + CN NH 2 = 



Ornithine Cyanamide 



NH 2 NH 2 



NH = C NH . CH 2 . CH 2 . CH 2 . CH . COOH 



Arginine 



B. Benech and F. Kutscher 3 succeeded in obtaining guanidine from 

 arginine, by oxidation with barium permanganate. 



We have only one group of the remaining protein decomposition 

 products to consider; that is, those containing sulphur. We have pre- 

 viously mentioned that sulphur is one of the essential constituents of 

 albumin. It is only absent from the protamines. The occurrence of 

 sulphur in proteins was recognized at an early date. It had been noted 

 that on boiling albuminous material with alkalies considerable amounts 



1 E. Fischer: Sitzber. Akad. Wiss. Berlin, 1900; Ber. 34, 454 (1901). 

 8 E. Schulze and E. Winterstein: Z. physiol. Chem. 34, 128 (1901). 

 3 E. Benech and Fr. Kutscher: ibid. 32, 278 (1901). 



