PUTREFACTIVE PRODUCTS OF THE PROTEINS. 81 



means of proteolytic enzymes are produced, and then a further decom- 

 position occurs with the formation of a large number of bodies belonging 

 in part to the aliphatic and in part to the aromatic and heterocyclic series. 

 Of the first series we have ammonium salts of volatile fatty acids, such 

 as caproic, valeric, and butyric acids, also succinic acid, carbon dioxide, 

 methane, hydrogen, sulphuretted hydrogen, methyl mercaptan, and 

 others. The ptomaines also belong to these products, and are probably 

 in part formed by very different chemical processes, or even syntheses. 



E. SALKOWSKI divides the putrefactive products of the aromatic 

 and heterocyclic series into three groups: (a) the phenol group, to which 

 tyrosine, the aromatic oxyacids, phenol, and cresol belong; (6) the phenyl 

 group, including phenylacetic acid and phenylpropionic acid; and 

 lastly (c) the indol group, which includes indol, skatol, indol propionic 

 acid and indol acetic acid. These various products are formed during 

 putrefaction with access of air. NENCKI and BOVET 1 obtained only 

 2>-oxyphenylpropionic acid, phenylpropionic acid, and skatolacetic acid 

 on the putrefaction of proteins by anaerobic schizomycetes in the 

 absence of oxygen. These three acids are produced by the action of 

 nascent hydrogen on the corresponding amino-acids, namely, tyrosine, 

 phenylaminopropionic acid, and skatolaminoacetic acid (indolamino- 

 propionic acid), and according to NENCKI these three last-mentioned 

 amino-acids exist preformed in the protein mplecule. 



By the moderate action of chlorine, bromine, or iodine upon proteins, 

 these halogens enter into more or less firm combination with the mole- 

 cule (LOEW, BLUM, BLUM and VAUBEL, LIEBRECHT, HOPKINS and BROOK, 

 HOFMEISTER, KURAJEFF, and others), and according to the method 

 of procedure we can prepare derivatives having different but constant 

 amounts of halogens (HOPKINS and PINKUS). The proteins are so changed 

 that they do not split off sulphur on treatment with alkali, nor do they 

 respond to MILLON'S reaction, nor do they yield tyrosine as a cleavage 

 product. According to SCHMIDT, oxidations and cleavages may take 

 place, as secondary processes, but more probably a substitution of hydro- 

 gen by halogen occurs in the aromatic nucleus of tyrosine or phenylamino- 

 propionic acid and perhaps also in the indol nucleus of tryptophane 

 and the imidazol nucleus of histidine. 2 



1 Salkowski, Zeitschr. f. physiol. Chem., 12, 215, and 27, 302; Nencki and Bovet, 

 Monatshefte f. Chem., 10. 



2 Loew, Journ. f. prakt. Chem. (N. F.), 31; Blum, Mimch. med. Wochenschr., 

 1896; Blum and Vaubel, Journ. f. prakt. Chem. (N. F.), 57; Liebrecht, Ber. d. deutsch. 

 chem. Gesellsch., 30; Hopkins and Brook, Journ. of Physiol., 22; Hopkins and Pin- 

 kus, Ber. d. deutsch. chem. Gesellsch., 31; Hofmeister, Zeitschr. f. physiol. Chem., 

 24; Kurajeff, ibid., 26; Oswald, Hofmeister's Beitrage, 3; C. H. L. Schmidt, Zeitschr. 

 f. physiol. Chem., 35, 36, 37; Neuberg, Biochem. Zeitschr., 6: Pauly and Gundermann, 

 Ber. d. d. chem. Gesellsch., 41. 



