ii PRIMARY DISSOCIATION-PRODUCTS 35 



the same method Kreusler l obtained it from casein, egg-white, and the 

 vitelline prepared from yolk ; Hlasiwetz and Habermann 2 employed 

 hydrochloric acid for its preparation from casein. Salkowski and 

 Radziejewski 3 got it by the tryptic digestion of fibrin, and E. Schulze 

 found it to represent one of the chief dissociation-products of many 

 germinating seeds (Tables, pp. 70-75). E. Fischer and his pupils have 

 obtained it from all albumins hitherto examined, except from fibroin, 

 but it is present everywhere only in very small quantities. According 

 to E. Fischer, 4 the acid occurring in albumins is Z-aspartic acid. It is 

 feebly laevo-rotatory in watery and alkaline solutions, while in strong 

 hydrochloric acid it is dextro-rotatory : 



a D = +25-7. 



Aspartic acid has not a sweet, but a strongly acid taste. 5 

 a Glutaminic Acid, C 5 H 9 N0 4 



O v H H NH 2 ,0 



^.f r\ r< r\ r\f 



> \J-\J \J \J ^\ 



HO X H H H ^OK, 



is a-amino-normal-glutaric acid, or a-Amino-normal-brenzweinsaure of 

 the Germans. This acid, also, was discovered by Bitthausen 6 in 

 vegetable albumins, and subsequently by Hlasiwetz and Habermann 2 

 on dissociating casein with hydrochloric acid ; by Knieriem 7 and 

 Kutscher 8 in tryptic digests of fibroin and in the albumins of the 

 pancreas. Later Kutscher 9 and E. Fischer demonstrated the very 

 wide distribution of this substance. With the exception of the 

 protamins and of silk, glutaminic acid can be demonstrated in consider- 

 able quantities in all albumins. Osborne and Harris 10 on hydrolysing 

 the alcohol-soluble wheat albumin gliadin with sulphuric acid obtained 

 25 per cent, and with hydrochloric acid an average minimal amount 

 of 36 per cent of glutaminic acid. This is, so far, the record amount 

 of any one amino-acid in a given albumin. Langstein n has demon- 



1 W. Kreusler, Journ. f. prakt. Chem. (1) 107. 240 (1869). 



2 Hlasiwetz and J. Habermann, Liebig's Annalen, 169. 150 (1873). 



3 E. Salkowski and J. Radziejewski, Ber. d. deutsch. chem. Ges. 7. II. 1050 (1874). 



4 E. Fischer, ibid. 32. II. 2451 (1899). 5 E. Fischer, ibid. 35. III. 2660 (1902). 



6 H. Ritthausen, Journ. f. prakt. Chem. (1) 106. 445 (1869) ; H. Ritthausen and 

 U. Kreusler, ibid. (2) 3. 314 (1871) ; H. Ritthausen, Die Getreidearten usw., Bonn, 

 M. Cohen and Co. (1872). 



7 Knieriem, Zeitschr. f. Biolog. 11. 199 (1875). 



8 F. Kutscher, Die Endprodukte der Trypsinverdauung, Marburger Habilitations- 

 schrift, Strasburg, Triibner, 1899. 



~ 9 F. Kutscher, Zeitschr. f. physiol. Chem. 38. Ill (1903). 



10 T. B. Osborne and I. F. Harris, Amer. Journ. of Physiol. 13. 35 (1905). 

 V 11 L. Langstein, Zeitschr. f. physiolog. Chem. 37. 508 (1903). 



