AMINES DERIVED FROM PROTEIN 23 



not identical with it, on account of a supposed difference in the physio- 

 logical action of the two bases. Iminazolyl-ethylamine has also been 

 obtained from the intestinal mucosa by Barger and Dale [1911]; 

 it is therefore present in crude solutions of secretine, to which it gives 

 a depressent action. Its formation in the intestinal wall is probably 

 due to bacilli, isolated by Mellanby and Twort [1912] and by Berthelot 

 and Bertrand [1912, I, 2]. The base has further been isolated from 

 putrid Soy beans by Yoshimura 1 [1910]; it probably also occurs in 

 commercial extracts of meat, of yeast, etc. 



The yield from almost all the above sources is very small ; larger 

 quantities may be prepared from histidine, as well as by direct syn- 

 thesis. The decarboxylation of histidine has been carried out indi- 

 rectly by Windaus and Vogt [1907] as mentioned above. 



The reactions involved are the transformation of histidine (I) 



CH-NH^ CH-NH, CH-NH. 



CH 3 . CH (NH 2 ) . COOH CH 2 . CHC1 . COOH CH a . CH a . COOH 



I II III 



CHNH. CH NHv CH 



<- C -- N 4- C __ 



CH 2 . CH 2 . NH 3 CH 2 . CH 2 . CONH . NH,, CH 2 . CH. . COOC a H 5 



VI V IV 



into a-chloro-/2-iminazolyl-propionic acid (II) (by sodium nitrite and 

 hydrochloric acid) ; the reduction of this substance to /3-iminazolyl- 

 propionic acid (III), which can also be synthesised from glyoxyl-propi- 

 onic acid ; the successive 'conversion of this acid into the ester (IV) 

 and the hydrazide (V) ; finally the conversion of the latter into the 

 azide and urethane (in alcoholic solution by amylnitrite and hydrogen 

 chloride) and the hydrolysis of the urethane by concentrated hydro- 

 chloric acid, which gives the hydrochloride of the desired amine (VI). 



The direct decarboxylation of histidine can be carried out more 

 conveniently by bacterial action and is applied industrially, according 

 to patents by Hoffmann, La Roche & Co. [1912], and by Farben- 

 fabriken vorm. F. Bayer & Co. (D.R.P. 250110). Details of the 

 method are given in the appendix. 



An attempt to decarboxylate histidine by heat alone results only 



1 Yoshimura [1909] probably obtained iminazolylethylamine by putrefaction before 

 Ackermann, but he did not identify it. He found that the Japanese beverage Tamari- 

 Shoyu, prepared from Soy beans, contains per litre o'7 grm. of a base C 6 H 9 N 3 , which he 

 surmised was derived from histidine. 



