1 3 8 THE CHEMICAL CONSTITUTION OF THE PROTEINS 



CH 2 .CHj.CH a .COOH CH,,. CH2.CH 2 COOH C . CH 2 . CH 3 COOH 



I I X\ 



CHO -> CH -> C.H 4 CH 



C 6 H / \X 



\/ NH 



N 2 H 



The indolepropionic acid obtained by hydrolysis was identical with 

 Nencki's skatoleacetic acid, and tryptophane was therefore either 



C . CH 2 CH(NH 2 )COOH C . CH(NH a )CH 2 COOH 



C 6 H/^)CH or C 6 H/^)CH 



NH NH 



and kynurenic acid must be formed by some other reaction. 



Hopkins and Cole had obtained by the oxidation of tryptophane with 

 ferric chloride a body of the composition of C 9 H 7 NO ; this body has 

 been shown by Ellinger to be y8-indole-aldehyde, firstly by oxidising 

 it to $-indole-carboxylic acid, 



C . CHO C . COOH 



NH NH 



a compound synthesised by Ciamician and Zatti, and secondly by 

 synthesis from indole and alcoholic chloroform. From this compound by 

 the method employed by Erlenmeyer in the synthesis of phenylalanine, 

 Ellinger and Flamand synthesised tryptophane in 1907: 



) By condensing /3-indolealdehyde with hippuric acid the azlactone is 

 obtained, 



N 



C CHO + CH 2 .NHCOC 6 H 5 C CH= C C . C 6 H 5 



CH/\CH 



fH NH 



which, when boiled with dilute soda, gives indolyl-a-benzoylaminoacrylic 

 acid, 



N 



C CH=C C.C 6 H 3 C CH=C.NH.COC 6 H g 



C 6 H 4 <^CH CO-O +NaOH =C 6 H 4 <^CH C OOH 



NH NH 



This compound on reduction with sodium amalgam and hydrolysis 

 with water gives tryptophane : 



C-CH^C . NHCOC 6 H B C CH, . CH(NH 2 ) 



CH COOH +H 2 +H 2 =C 6 H 4 <^CH COOH + C 6 H 5 COOH 

 NH NH 



