AMINES DERIVED FROM PROTEIN 9 



the carbon chain in the production of succinic acid from glutamic acid 

 by putrefaction. 



Some putrefaction bases are formed from substances other than 

 proteins ; thus lecithin is broken down to choline, neurine, trimethyl- 

 amine, monomethylamine, and ammonia; creatine yields monomethyl- 

 guanidine and perhaps also dimethylguanidine ; the trimethylamine of 

 stale urine is derived from more complex betaines ; purine and pyrimid- 

 ine bases probably also contribute to the formation of putrefaction bases. 



When an entire tissue or organ, and to a less extent when a single 

 protein is putrefied, as in the experiments of Nencki, Gautier, Brieger, 

 Salkowski, Emmerling, Barger and Walpole, and the earlier experi- 

 ments of Ackermann, a complex mixture of bases is obtained from 

 various parent substances. A better insight into the chemistry of 

 putrefaction is possible when a simple substance, such as a single 

 amino-acid, is subjected to bacterial action. This method depends on 

 a knowledge of the constituents of protein, and was first applied to the 

 study of bases by Ellinger, who showed that putrescine and cadaverine 

 are derived from ornithine and lysine respectively. Further work in 

 this direction has been carried out principally by Ackermann and by 

 Neuberg. (The products of the action of bacteria on indole-propionic 

 acid (Nencki) and of yeast on proteins (F. Ehrlich) are not bases, and 

 they are therefore not included in this monograph.) It is generally 

 much more difficult to grow bacteria in a solution of a pure amino-acid 

 than on protein, and Ackermann therefore adds 0^25 per cent. Witte pep- 

 tone to the solution, together with 0*5 percent, glucose and a few drops 

 of sodium phosphate and magnesium sulphate ; calcium carbonate is 

 sometimes added to prevent the solution becoming acid, but a faint 

 alkaline reaction is secured more certainly by adding sodium carbonate 

 from time to time. Although Neuberg [1911, l] has pointed out the 

 theoretical objections to the addition of peptone he yet agrees with 

 Ackermann that in many cases this addition is desirable. For the 

 decomposition of histidine Mellanby and Twort [1912] used a culture 

 medium containing only ammonium tartrate and inorganic salts (see 

 p. 133). A similar medium was used by Berthelot and Bertrand 

 [1912, I]. 



Of late years nearly all the putrefaction products, which might be 

 expected to result from the known amino-acids, have been obtained 

 by bacterial action. Exceptions are e-amino-caproic acid which might 

 be formed from lysine, guanidino-valeric acid (from arginine), pyrroli- 

 dine (from proline), oxypyrrolidine (from oxyproline) and the amines 

 from cystine and serine. 



