ALANINE. VAL1NE. 139 



cipitated by BaCOs, and the filtrate evaporated to the point of crystal- 

 lization. (In regard to its preparation from protein substances see below.) 



CH 3 



Alanine (a-aminopropionic acid, C 3 H 7 NO 2 = CH (NH 2 ) . The d-alanine 



COOH 



is obtained in relatively small amounts from the true proteids, but in 

 larger quantities from the albuminoids, especially from fibroin, spider- 

 silk and elastin. 



d-alanine has been prepared from -serine by E. FISCHER and K. 

 RASKE l , and FISCHER has also obtained it from racemic alanine by split- 

 ting the benzoyl combination or from Z-alanine by splitting with yeast 

 by WALDEN'S reversion (see page 87). 



Alanine generally crystallizes in needles or oblique rhombic columns. 

 It is very readily soluble in water, having a sweetish taste, and dissolves 

 cupric hydroxide on boiling, producing a deep blue solution of acrystalliza- 

 ble copper salt. Alanine is insoluble in absolute alcohol. The rota- 

 tion of alanine at 20 C. in aqueous solution is (a) D =+2.7 and for a 

 solution in hydrochloric acid (9-10 per cent solution) is (a) D = + 10.3. 



The ^-naphthalene-sulpho-d-alanine melts at 79-81, the phenyliso- 

 cyanate at 168, and the naphthylisocyanate-alanine melts at 198 C. 



CH3 



V 



OTT 

 Valine (a-amino-valeric acid) C 5 H 



COOH 



detected several times among the cleavage products of protein sub- 

 stances, although only in small quantities. KOSSEL and DAKIN obtained 

 4.3 per cent valine from salmine, and E. FISCHER and DORPINGHAUS 2 

 5.7 per cent from horn substances. The acid isolated by H. and E. 

 SALKOWSKI 3 from putrefying proteid or gelatin seems to have been 

 a-amino-n-valeric acid. 



c/-valine can be obtained as microscopic crystalline leaves. It is 

 rather readily soluble in water and the solution has a faint sweetish taste 

 and at the same time somewhat bitter. The solution has a rotation 

 of (a) D =+6.42. The hydrochloric acid solution (20 per cent) shows, 

 according to FISCHER, a rotation of (a) D =+28.8. The copper salt, 

 which forms leaves which are rather soluble in water, is very easily soluble 

 in methyl alcohol (SCHULZ and WINTERSTEIN 4 ) . 



1 Ber. d. d. chem. Gesellsch., 40. 



2 Kossel and Dakin, Zeitschr. f. physiol. Chem., 41; Fischer and Dorpinghaus, 

 ibid., 36. 



8 Ber. d. d. chem. Gesellsch., 16 and 31. 

 4 Zeitschr. f. physiol. Chem., 35. 



