150 CHEMISTRY OF THE PROTEIDS CHAP. 



action of trypsin on albumin a part of the latter is readily dissociated 

 into amino-acids and bases, and that thereby peptones are formed 

 which do not contain the tyrosin group and which vigorously with- 

 stand a further dissociation by means of trypsin." 



By tryptic digestion fibroin yields two acid anti-peptones, which 

 on dissociation give rise to lysin, arginin, glutaminic acid, ammonia, 

 and perhaps serin and aspartic acid ; by careful dissociation with acids 

 there is formed either directly from gelatine or from an acid 

 gelatine-peptone the substance glutokyrin. This kyrin is a crystalline 

 peptone (see p. 200) ; it contains lysin, arginin, glutaminic acid, and 

 glycocoll, and is a fairly strong base because of the preponderance of 

 the basic constituents. 



How the polypeptids of Fischer and Abderhalden and this kyrin 

 are related to one another is not yet clear. Both contain glutaminic 

 acid and glycocoll ; the di-amino-acids, which make up the greater 

 bulk of the kyrin, have so far not been investigated in the polypeptid, 

 but attention is drawn to E. Fischer's l statement that pyrrolidin- 

 carboxylic acid and the hexone bases usually occur together. One 

 thing is certain, namely, that we have to do with a very considerable 

 fraction of the proteid- molecule linked together in some particular 

 way. Erepsin acts on anti-peptone in such a way that it no longer 

 gives the biuret-reaction. 2 



It seems to be a common phenomenon, that after the first splitting 

 off of a part of the albumin there remain behind substances which 

 apparently do not differ much from the material we started with, 

 substances which still bear the chemical character of albumins. That 

 such a result is produced by trypsin and that kyrin is formed has 

 been explained above, but on dissociating natural albumins with dilute 

 hydrochloric acid, Goldschmidt 3 saw that different albumoses and 

 peptones appeared simultaneously, even before acid -albumin was 

 formed; during peptic digestion Umber, 4 Zunz, 5 and others noticed 

 acid - albumin together with peptones and abiuretic dissociation- 

 products ; analogous observations have been made by Maas, 6 who 

 dissociated albumins by means of alkalies. By oxidising albumins with 

 permanganate in alkaline solutions, Berriert 7 found a certain per- 

 centage of the albumins to dissociate very rapidly into albumoses, 



1 E. Fischer, Zeitschr. f. physiol. Chem. 39. 155 (1903). 



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



3 F. Goldschmidt, Einwirkung von Sauren auf Eiweissstoffe, Dissertation. Strass- 

 burg, 1898. 4 F. Umber, Zeitschr. /. physiol. Chem. 25. 258 (1898). 



5 E. Zunz, ibid. 28. 132 (1899) ; Hofmeister's Beitr. 2. 435 (1902), 3. 339 (1902). 



6 0. Maas, Zeitschr. f. physiol. Chem. 30. 61 (1900). 



7 K. Bernert, ibid. 26. 272 (1898). 



