THE CHEMISTRY OF ALBUMINS 195 



It probably occurs as a decomposition product of albumin, 

 in the form of skatol-amino-acetic acid : 



CH 



C.CH(NH 2 ).COOH 



H 



2. Alanin or a-amino-propionic add, CH 3 CHNH 2 COOH. 

 This acid has been shown by Emil Fischer to be widely 

 distributed as a decomposition product of albuminoids. Its 

 derivatives have many of them been well known for some time, 

 especially phenyl-alanin, that is C 6 H 5 CH 2 CHNH 2 COOH, and 

 para-hydroxy-phenyl-alanin, more commonly known as tyrosin> 



CH 2 CHNH 2 COOH 



Tyrosin is easily isolated on account of its sparing solubility ; 

 it is one of the products of excretion of the animal body and 

 occurs together with leucin. 



Other derivatives of alanin give rise to the very important 

 substances indol and skatol already mentioned. A sub- 

 stance termed tryptophane has been isolated from the mixture 

 of substances produced by the action of trypsin on albumin. 

 Some amount of discussion has taken place as to the constitu- 

 tion of this body ; it appears certainly to be an indol-amino- 

 propionic acid. Indol-amino-propionic acid or tryptophane 

 will therefore have either of the two following formulae : 



02 



