ALBUMINS OR PROTEINS. 169 



but which, nevertheless, probably do not occur as a constituent of the 

 original molecule. 



Amongst these is leucinimide. It is an anhydride of leucine, and is 3-6, 

 di-isobutyl, 2-5, di-acipiperazine: 



C 4 H 9 . CH . NH . CO 



. NH . CH . C 4 H 9 



Ritthausen * first observed this in an acid hydrolysis. Cohn 2 also 

 described it. Salaskin and Kowalewsky 3 recently even separated it, 

 although only in minute quantity, from peptic and tryptic digestion. 4 It 

 has not yet been decided whether leucinimide occurs as such in the 

 albumin molecule. It is possible that it is formed by a secondary process, 

 perhaps from a leucyl-leucine. 



Pyroracemic acid, CHg . CO . COOH, discovered by Morner, 5 is un- 

 questionably formed by a secondary reaction. It is probably produced 

 from alanine, serine, or cystine. The origin of a-thiolactic acid, discovered 

 by Suter, 8 is problematical. It may possibly be derived from cystine, 

 although this has the thio group in the /? position. Ornithine, which is 

 certainly a secondary decomposition product, is derived from arginine. 



The albumins quickly undergo putrefaction. 7 They are also decomposed 

 by bacteria in the intestines. It is necessary to become acquainted with 

 the compounds formed in this manner. They are all related to the amino 

 acids already mentioned. The bacteria decompose the albumin in the 

 same manner as do the proteolytic ferments, especially trypsin. Peptones, 

 and finally amino acids, are produced. 



1 Ritthausen: Die Eiweisskorper der Getreidearten, Bonn, 1872. 

 8 R. Cohn: Z. physiol. Chem. 22, 153 (1896-97); 29, 283 (1900). 



3 S. Salaskin and K. Kowalewsky: ibid. 38, 567 (1903). 



4 The author has himself also tried to isolate leucinimide from peptic and tryptic 

 digestion products, but in vain. Something went into solution in the acetic ether. Its 

 easy solubility in dilute hydrochloric acid showed that it was not leucinimide. He, 

 however, succeeded in obtaining about one per cent of leucinimide by hydrolyzing 

 casein with 25 per cent sulphuric acid. 



5 K. A. H. Morner: Z. physiol. Chem. 42, 121 (1904). 



1 Suter: ibid. 20, 564 and 577 (1895); Hofmeister's Beitr. 3, 184 (1902). K. A. H. 

 Morner: Z. physiol. Chem. 42, 365 (1904). 



7 E. and H. Salkowski: Z. physiol. Chem. 8, 417 (1884); ibid. 9, 8 (1884); 9, 491 

 (1885); 27, 302 (1899). N. Nencki: Ber. 7, 1593 (1874); 8, 336 (1875); 10, 1032 (1877); 

 J. pr. Chem. 26, 47 (1882); Z. physiol. Chem. 4, 371 (1880); Z. med. Wiss. 1878, 47. 

 Nencki: Opera omnia, vol. i, pp. 92, 113, 144, 244, 246, 674, 537, 354, 418, etc. 

 E. Baumann: Ber. 12, 1450 (1879); Z. physiol. Chem. 4, 304 (1880); 6, 183 (1882); 7, 

 282 and 553 (1895). E. Baumann and L. Brieger: ibid. 3, 149 and 284 (1879). L. 

 Brieger: J. pr. Chem. 17, 124 (1877); Ber. 10, 1027 (1877); 12, 1986 (1879); Z. 

 physiol. Chem. 2, 241 (1878); 3, 134 (1879); 4, 414 (1880); 6, 366 (1881). Cf. also L. 

 Brieger: Die Ptomaine, Berlin, 1886. 



