194 CHEMISTRY OF THE PROTEIDS CHAP. 



mann, 1 Hedin, 2 Kutscher, 3 Kiilz, 4 and E. Fischer and Abderhalden 5 

 added to these three products nearly all the other dissociation-products. 

 How our knowledge about tryptic action was further developed has 

 already been alluded to on p. 144. It is definitely known that trypsin 

 can only dissociate one portion of the albumin -molecule, and that a 

 proteid-residue remains even after trypsin has acted for months. This 

 compound, according to E. Fischer and Abderhalden, is a polypeptid \ 

 it is precipitated by phosphotungstic acid, and, on being dissociated 

 with acids, yields glycocoll, a-pyrrolidin-carboxylic acid, phenylalanin, 

 alanin, leucin, and aspartic and glutaminic acids. The three com- 

 pounds mentioned first are only found in the polypeptid, while the 

 other substances are also found in the digested portion of the tryptic 

 digest. The di-amino acids have not yet been determined. 



In addition to the polypeptid just mentioned, peptone is also found. 

 The latter gives the biuret-reaction, and has been called * anti-peptone ' 

 by Kiihne. According to Kutscher, 3 Siegfried, 6 Mays, 7 Lowi, 8 and 

 Lawrow, 9 its resistance is only relative, as it is dissociated still further 

 by intense tryptic digestion ; but the difference, compared with the 

 readily digested albumin, is very great. While, according to E. Fischer 

 and Abderhalden, 5 tyrosin is split off with such rapidity as to suggest that 

 this amino-acid simply crystallises out, it takes weeks and even months 

 for the biuret-reaction of the anti-peptone to disappear. Erepsin 

 disintegrates anti-peptone also, only very slowly 10 (Cohnheim). 



The anti -peptones, for there are several, Siegfried 11 and his 

 pupils 12 have prepared in a pure state by adding iron-ammonia-alum to 

 saturated ammonium sulphate solutions. From fibrin they obtained 



a Anti-peptone C 10 H 17 N 3 5 (C 46'2 ; H 6'74 ; N 16'26 per cent). 

 ft Anti-peptone C n H 19 N 2 5 (C 48'23 ; H 7'12 ; N 15'41 ). 



I E. Stadelmann, Zeitschr.f. Biol. 24. 261 (1888). 



3 S. G. Hedin, Arch.f. (Anat. und) Physiol. 1891, p. 73. 



3 F. Kutscher, Zeitschr. /. physiol Chem. 25. 195 (1898), 26. 110 (1898), 28. 

 88 (1899) ; Endprodukte der Trypsinverdauung, Marburg, 1899 (here a full account of 

 the literature). 4 E. Kiilz, Zeitschr.f. Biol. 27. 415 (1890). 



E. Fischer and E. Abderhalden, Zeitschr. f. physiol. Chem. 39. 81 (1903). 



M. Siegfried, Ber. d. deutsch. chem. Oes. 33. III. 3564 (1900). 



K. Mays, Zeitschr. f. physiol. Chem. 38. 428 (1903). 



0. Lowi, Schmiedeberg's Arch. 48. 303 (1902). 



D. Lawrow, Zeitschr.f. physiol. Chem. 26. 513 (1899). 

 10 0. Cohnheim, ibid. 35. 134 (1902). 



II M. Siegfried, Zeitschr. f. physiol. Chem. 27. 335 (1899) ; Ber. d. deutsch. chem. 

 Oes. 33. HI. 2851 (1900), 33. III. 3564 (1900) ; Zeitschr. f. physiol. Chem. 35. 164 

 (1902), 38. 259 (1903). 



12 Fr. Miiller, ibid. 38. 265 (1903) (in this paper the methods are fully discussed) ; 

 T. R. Kriiger, ibid. 38. 320 (1903). 



