ii PRIMARY DISSOCIATION-PRODUCTS 47 



D = -81-04. 



It is very soluble in water ; very slightly soluble in alcohol. It 

 tastes sweet. 



24. Phenylalanin, C 9 H n N0 2 



<O CH 2 CH(NH 2 ) . COOH, 



is phenyl-a-amino-propionic acid. E. Schulze 1 first succeeded in 

 isolating it from germinating plants, although its occurrence in 

 albumin had previously been assumed, because, when albumin is 

 decomposed by putrefactive bacteria, there are formed, in addition 

 to phenol, cresol, oxyphenyl-acetic and oxyphenyl-propionic acids, 

 which are derived from tyrosin, also phenyl-ethylamin, phenyl- 

 acetic, and phenyl-propionic acids. Nencki 2 and Salkowski 3 assumed 

 the last mentioned substances to be derived from the mother substance 

 phenyl-amino-propionic acid. Guckelberger, 4 Maly, 5 Bernert, 6 Pick, 7 

 Ducceschi, 8 and Spiro 9 also found derivatives of a non-hydroxylated 

 amino-acid. E. Fischer and his pupils succeeded in demonstrating the 

 occurrence of phenylalanin in all the proteids they investigated, and 

 indeed, 'as Nencki 10 had already assumed, in such quantities that it was 

 at least equal to, and in many cases in excess of, the other aromatic 

 body present, namely, tyrosin (compare tables on pp. 70-75). In the 

 albumin-molecule, phenylalanin occurs, along with glycocoll and a-pyrro- 

 lidin-carboxylio acid, only in the so-eq.u e d anti-group, 11 and is therefore 

 characteristic of this group, in which the +.y r0 sin radical is absent. 



The naturally occurring phenylalanin is the 7_ var i e ty.i2 E. Schulze 

 and Winterstein 13 determined 



a D = -38-1 to 40-2. 



1 E. Schulze and E. Bosshard, Zeitschr. f. physiol. Chem. 9. 63 (1884) ; E. Schulze, 



ibid. 17. 193 (1892). 



2 M. Nencki, Monatshefte fur Chemie, 10. 506, 526, 862, 864, 908 (1889). 



3 E.'and H. Salkowski, Zeitschr. f. physiol. Chem. 8. 417 (1884), 9. 8 (1884), 9. 

 491 (1885) ; E. Salkowski, Die Lehre vom Harn, p. 26, 1872 ; Ber. d. deutsch. chem. 

 Ges. 34 III. 3884 (1901). 



4 Guckelberger, Liebig's Annalen, 64. 39 (1848). 

 s R. Maly, Monatshefte f. Chemie, 10. 26 (1889). 



6 R. Bemert, Zeitschr. f. physiol. Chem. 26. 272 (1898). 



7 E. P. Pick, ibid. 28. 219 (1899). 



8 V. DuccescM, Hofmeisters Beitrdge, 1. 338 (1901). 



9 K. Spiro, ibid. 1. 347 (1901). 



10 M. Neucki, Monatsh. f. Chem. 10. 506 (1889). 



n E. P. Pick, Zeitschr. f. physiol. Chem. 28. 219 (1899); E. Fischer and 

 Abderhalden, ibid. 39. 81 (1903). 



12 E. Schulze arid E. Winterstein, ibid. 35. 299 (1902) ; E. Fischer and 

 Mouneyrat, Ber. d. deutsch. chem. Ges. 33- II. 2383 (1900). 



13 E. Schulze and E. Winterstein, Zeiischr. f. physiol. Chem. 35- 299 



