GLUTAMIC ACID. 145 



Z-Aspartic acid dissolves in 256 parts water at 10 C. and in 18.6 parts 

 boiling water, and on cooling crystallizes as rhombic prisms, and its 

 4 per cent solution acidified with HC1 has the rotation (a) D = +25.7; 

 in alkaline solution the acid is levo-rotatory. It forms with copper 

 oxide a crystalline compound which is soluble in boiling-hot water and 

 nearly insoluble in cold water, and which may be used in the preparation 

 of the pure acid from a mixture with other bodies. 



The benzoyl-/-aspartic acid melts at 184-185. For identification 

 we make use of the analysis of the free acid and the copper salt, as well 

 as of the specific rotation. 



COOH 

 CH(NH 2 ), 



Glutamic acid (a-aminoglutaric acid) , CsHgNC^ = CH 2 , is obtained 



CH 2 

 COOH 



from the protein substances under the same conditions as the other mon- 

 amino-acids (see tables on pages 106, 107, 114 and 124) and from the pep- 

 tones (SIEGFRIED). HLASIWETZ and HABERMANN obtained 29 per cent 

 from casein by cleavage with hydrochloric acid, while KUTSCHER could 

 obtain only 1.8 per cent glutamic acid by cleavage with sulphuric acid. 

 ABDERHALDEN and FUNK l did not find any such differences in the hydro- 

 lytic action of the two acids, and obtained only 10-11 per cent glutamic 

 acid from casein. SKRAUP and TURK 2 obtained on the hydrolysis of casein 

 with 33 per cent sulphuric acid at boiling temperature for eighteen hours 

 about the same quantity of glutamic acid as on boiling for six hours with 

 fuming hydrochloric acid, namely, 20.3 and 22.3 per cent glutamic acid 

 hydrochloride. The considerable quantity of glutamic acid obtainable 

 from certain vegetable proteins, as shown on page 107, is very remarka- 

 ble. LEVENE and MANDEL 3 have found a strikingly large quantity of 

 glutamic acid, namely 25 per cent, from a nucleoprotein from the spleen. 



d-Glutamic acid crystallizes in rhombic tetrahedra or octahedra or in 

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

 tastes acid with a peculiar after-taste. It is insoluble in alcohol and in 

 ether. 



In water it has a rotation of (a) D =+ 12.04 according to ANDRLiK. 4 

 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. The 



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

 f. physiol. Chem., 28; Abderhalden and Funk, ibid., 53. 



2 Monatsh. f . chem., 30. 



3 Biochem. Zeitschr., 5. 



4 See Biochem. Centralbl., 3, p. 469. 



