34 THE SIMPLER NATURAL BASES 



CH, CH, 



CH, CH . COOH + aH = NH, . CH, . CH, . CH, . CH, . COOH. 

 NH 



The a>-amino-acids differ from a-amino-acids in being precipitated by 

 phosphotungstic acid, even in dilute solutions ; they yield platini- 

 chlorides soluble in alcohol (Ackermann). The 7-, S-, and e-amino- 

 acids are so weakly acidic that they do not form blue copper salts on 

 boiling with cupric oxide, or on addition of cupric acetate, this pro- 

 perty belonging only to a- and /9-amino-acids (Fischer and Zemplen 

 [1909, p. 4883]). On heating 7-amino-butyric and -amino-valeric 

 acids are transformed into their anhydrides, pyrrolidone and piperidone. 



- Alanine, /9-amino-propionic Acid, NH 8 . CH 2 . CH 2 . COOH. 



This substance, long known synthetically, was first isolated from 

 Liebig's extract of meat by Engeland [1908, l] ; Micko [1905] had 

 previously obtained an alanine from the same source and assumed that 

 it was the a-amino-acid 



/S-Alanine is formed from the meat base carnosine by hydrolysis 

 (see next section), and since Engeland's process of isolation involved 

 evaporation in hydrochloric acid solution, Gulewitsch [1911; see 

 under carnosine] questions whether ^-alanine is present as such in 

 muscle. 



It was to be expected that /J-alanine could also be formed from 

 aspartic acid by putrefaction, according to the second general method 

 given in the preceding section, and after some failures Ackermann 

 [1911, I] has succeeded in demonstrating this. 



One hundred grm. of aspartic acid in a culture medium similar 

 to that used for preparing /9-iminazolyl-ethylamine yielded 2 grm. of 

 y3-alanine hydrochloride. 



$- Alanine is broken down to urea in the dog (Abderhalden and 

 Schittenhelm [1907]). 



7-Amino-n-butyric Acid, NH, . CH a . CH 2 . CH 2 . COOH. 



This acid is formed in putrefaction from glutamic acid by the 

 second general process (p. 33). 



Ackermann [1910, 3] obtained 2'i grm. of 7-amino-butyric acid 

 aurichloride from 50 grm. of glutamic acid. Abderhalden and Kautzsch 

 [1912] lately failed to repeat Ackermann's experiment, but afterwards 

 Abderhalden, Fromme and Hirsch [1913] obtained o'3 grm. of the 

 platinichloride of 7-amino-butyric acid from 25 grm. of glutamic acid 



