CHAPTER I. 



AMINES DERIVED FROM PROTEIN. 



The Putrefactive Decomposition of Amino-acids. 



BOTH animals and plants decompose proteins into their constituent 

 amino-acids ; the hydrolysis by trypsin and by erepsin in animals is 

 similar to the formation of amino-acids in germinating seeds, which 

 has been studied especially by Schulze and his pupils. The hydrolysis 

 of proteins into their constituent amino-acids is also the first stage of 

 putrefaction, but bacteria (and other fungi) are peculiar in being able 

 to break down the amino-acids themselves into bases and acids which 

 in general have not been demonstrated as products of the metabolism 

 of animals and the higher plants. 



This degradation may take place in two ways : either an amino- 

 group may be eliminated (deaminization) or a carboxyl-group may be 

 removed (decarboxylation) ; various modifications and combinations of 

 these two processes are possible. Little is known about the conditions 

 determining which process takes place ; generally the two go on 

 simultaneously and deaminization preponderates. Ackermann who 

 has carried out a number of experiments on the bacterial decarboxy- 

 lation of pure amino-acids, finds that this process is favoured by the 

 addition of peptone which serves as a source of nitrogen and in this 

 way lessens deaminization. -An organism which decarboxylates histi- 

 dine has been isolated by Mellanby and Twort [1912]. Berthelot 

 and Bertrand [1912, I, 2; 1913, I, 2 ; Bertrand and Berthelot, 1913] 

 have described a similar organism from the human intestine, Bacillus 

 aminophilus intestinalis, which decarboxylates histidine, tyrosine, tryp- 

 tophane, etc. 



The various amines dealt with in the present chapter are all deriv- 

 able from monobasic amino-acids by decarboxylation, and it is therefore 

 with this process that we are more particularly concerned. Decar- 

 boxylation may take place by the simple removal of carbon dioxide : 



R R 



CHNH, = CH a . NH a + CO,. 



! COO i 



