GLUTAMIC ACID. 147 



investigators such as ABDERHALDEN and FUNK and SKRAUP and TURK 

 have shown that the same quantities of glutamic acid can be obtained 

 by the use of the two mineral acids. SKRAUP and TURK obtained on the 

 hydrolysis of casein 20.3-22.3 per cent glutamic acid hydrochloride 

 corresponding to about 17 per cent glutamic acid. ABDERHALDEN and 

 SASAKI 1 obtained 13.6 per cent glutamic acid from meat syntonin. It 

 occurs most abundantly in the plant proteins where the quantity may 

 be more than 40 per cent. LEVENE and MANDEL 2 have obtained a strik- 

 ingly large quantity of glutamic acid, namely 25 per cent, from a nucleo- 

 protein of the spleen. 



On heating glutamic acid to 180-190 it is converted into pyrrolidon- 

 carboxylic acid, which latter can be re transformed into glutamic acid 

 by HC1 gas; therefore, a formation of pyrrolidon-carboxylic acid at the 

 same time, or in place of glutamic acid, in the hydrclyses, is not excluded. 



On putrefaction glutamic acid gives 7-aminobutyric acid, n-butyric 

 acid and succinic acid. 



d-Glutamic acid crystallizes in rhombic tetrahedra or octahedra or 

 in small leaves. It dissolves in 100 parts water at 16 C., and the solu- 

 tion has an acid taste with a peculiar after-taste. It is insoluble in 

 alcohol and in ether. 



In water it has a rotation of (a) D = +12.04. Strong acids increase 

 the rotation, and a 5 per cent solution of glutamic acid containing 9 per 

 cent HC1 has a rotation (a) D =+31.7, while that obtained by heating 

 with barium hydroxide is optically inactive. d-Glutamic acid forms 

 a beautifully crystalline combination with hydrochloric acid, which is 

 almost insoluble in concentrated hydrochloric acid. This compound 

 is used in the isolation of glutamic acid. On boiling with cupric hydroxide 

 a beautiful crystalline copper salt, which is soluble with difficulty, is 

 obtained. 3 The benzoyl-d-glutamic acid melts at 130-132 C. The 

 hydrochloride, the a-naphthylisocyanate of glutamic acid, which melts 

 at 236-237 C., the analysis of the free acid, and the specific rotation 

 are used in its detection. 



As previously stated monamino-oxydicarboxylic acids have also 

 been found among the cleavage products of the proteins. To these belong 

 the following: 



That oxyaminosuccinic acid, C n H 7 NOi occurs among the hydrolytic cleavage 

 products of proteids has been shown to be probable by SKRAUP. This acid has 



1 Hlasiwetz and Habermann, Annal. d. chem. u. Pharm., 159; Kutscher, Zeitschr., 

 f. physiol. Chem., 28; Abderhalden and Funk, ibid., 53; with Sasaki, ibid., 51; Skraup 

 and Turk, Monatsch. f. Chem., 30. 



2 Bioch. Zeitschr, 5. 



3 Several salts of glutamic acid have been prepared and studied by Abderhalden 

 and Kautzsch, Zeitschr. f. physiol. Chem., 64, 68, and 78. 



