TRYPTOPHANE. 155 



hydrochloric acid, at the same time splitting off water. Recently he 

 has suggested another method which yields good results. Other syn- 

 theses of proline have also been performed by E. FISCHER and WILL- 

 STATTER. 1 By the reduction of the ethyl ester of pyrrolidon carboxylic 

 acid (see glutamic acid) E. FISCHER and BOEHNER 2 have obtained racemic 

 a-proline. On putrefaction proline yields 6-amino-valeric acid and n- 

 valeric acid (NEUBERG and AcKERMANN 3 ). 



/-Proline crystallizes in flat needles. It is readily soluble in water 

 and alcohol. The solution has a sweet taste; the specific rotation at 

 20 C. is (a) D = 77.40. The solution acidified with sulphuric acid is 

 precipitated by phosphotungstic acid. In the detection of this acid 

 we make use of the copper salt, the anhydride of the phenylisocyanate 

 compound (melting-point 144), and the picrate. The inactive acid and 

 its compounds show somewhat different properties. 



Oxyproline (oxy-a-pyrolidine carboxylic acid), CsHgNOa. This acid, 

 whose constitution is not understood was first obtained by E. FISCHER 

 on the hydrolysis of casein and of gelatin. It dissolves readily in water; 

 has a specific rotation of () D = 81.04, and the solution has a sweet 

 taste. Oxyproline crystallizes in beautiful colorless plates and gives 

 a readily soluble copper salt. The constitution of natural oxyproline 

 has recently been explained by LEUCHS and BREWSTER. 4 They find 

 that the natural oxyproline is a 7-oxy-derivative -of pyrrolidine-a-carbox- 

 ylic acid. LEUCHS found the specific rotation of Z-oxyproline to be 

 ( a ) D= _76 at 20 C. 



/-Tryptophane (indol-a-aminopropionic acid), 



C.CH 2 .CH(NH 2 )COOH 



NH 



is*one of the cleavage products of the proteins formed in tryptic diges- 

 tion and other deep decompositions of the proteins, such as putrefaction, 

 cleavage with baryta-water or sulphuric acid. It gives a reddish-violet 

 product with chlorine or bromine which is called proteinochrome. NENCKI 5 

 considered tryptophane, which name is generally given to this acid, 

 as the mother-substance of various animal pigments. 



1 Ber. d. d. chem.. Gesellsch., 33. 



2 Ber. d. d. Chem., Gesellsch., 44. 



* Neuberg, Bioch. Zeitschr, 37; Ackermann, Zeitschr. of Biol., &7-. 



4 Fischer, Ber. d. d. chem. Gesellsch., 35 and 36; Leuchs and Brewster, Ber. d. d. 

 Chem., Gesellsch., 46. 



5 In regard to tryptophane, see Stadelmann, Zeitschr. f. Biologie, 26; Neumeister, 

 ibid., 26; Nencki, Ber. d. d. chem. Gesellsch./*28; Beitler, ibid., M; Kurajeff, Zeitschr. 

 f. physiol. Chem., 26; Klug, Pfliiger's Arch.,. 86. 



