1882.] Leucine and Olycocine into Urea. 179 



So much for the physiological side. Let us turn to the patho- 

 logical. Frerichs* pointed out that in acute atrophy of the liver, 

 the urine contains a large quantity of leucine and tyrosine, and 

 that urea almost or entirely disappears. 



It is evident from these statements, that leucine, when intro- 

 duced into the alimentary canal of a healthy animal, is converted 

 into urea, and that the conversion takes place in the liver. But, 

 if so, what becomes of the residue ? Is it possible that it is 

 converted into an alcohol, and thence into a cyanhydrin, to 

 undergo the series of changes I have just described; the urea 

 being eliminated by the kidneys ? Now, there is a compound 

 having the same ultimate composition as leucine, from which both 

 urea and amylic alcohol can be obtained, viz. isopentyl carba- 

 mate or urethane — 



C 6 H 10 | C0( 5 H = C 6 H 13 N0 2 = CO | 00 ^ 



leucine isopentyl carbamate 



or urethane 



This substance acted upon by ammonia is decomposed into 

 amyl alcohol and ureaf — 



"{pew, +NH - - C * H »- H0 + co §5 



isopentyl carbamate amylic alcohol urea 



If, then, we assume that during pancreatic digestion (and I will 

 presently indicate how the change may take place) there is a 

 molecular transformation of leucine into a carbamate, that this on 

 passing into the liver comes in contact with ammonia, the product 

 of tissue disintegration, and so is converted into urea and alcohol, 

 we have a complete series of transformations which may take 

 place in the animal system, and the question as to the formation 

 of urea is solved. 



The same series of changes holds good for alanine — 



_ „ fNH 2 . t , . x __ fNH 2 



C 2 H 4 < p 00 TT 1S converted into CO j 



alanine ethyl urethane 



The urethane combining with ammonia is converted into alcohol 

 and urea — 



co & +nh '= c ' h '- ho;co {nh; 



alcohol urea 



* Klinik der Lcberkranlchciten, 1858. s. 206. t Fownes, p. 390. 



