188 CHEMISTRY OF THE PROTEIDS CHAP. 



From fibrin two peptones may be prepared which differ from one 

 another in 1 molecule of H 2 0, and which may be converted into one 

 another. From 1 1 kgrms. wet fibrin Borkel obtained, after repeated 

 purification, accompanied by great loss, 203 grms. peptone. The 

 analyses gave these figures : 



Pepsin-peptone a . . . . C 21 H 34 N (J 9 . 

 Pepsin-peptone/? . . C 21 H 36 N 6 10 . 



Peptones are " pronounced acids, which redden litmus paper, and 

 which form salts with carbonates after having driven out the carbonic 

 acid." Siegfried is of the opinion that Kiihne's peptones were 

 ammonium salts. Borkel has analysed the zinc-salts of both peptones, 

 and Miihle the silver and barium salts. Adopting the simplest 

 formula, peptones are monobasic acids, but such a simple formula has 

 to be multiplied. Peptones are Ia3vo- rotatory. Borkel found for 

 a-pepsin-peptone 



a|= -36-36. 



The ammonium salt is more strongly Isevo-rotatory. It reacts towards 

 precipitating reagents as do other peptones. It gives the reactions of 

 Millon and of Adamkiewicz-Hopkins, but not that of Molisch. 



On being acted upon with trypsin, pepsin-peptone yields tyrosin, 

 arginin, and the two trypsin-peptones (see below), which in their turn 

 contain lysin, arginin, glutaminic and aspartic acids, and ammonia. 

 As, further, the Adamkiewicz-Hopkins, or, to put it shorter, 'the 

 glyoxylic acid,' reaction indicates tryptophane, the pepsin -peptone 

 must be a very complicated substance a fact which makes its 

 constancy all the more remarkable. 



From glutin Siegfried and Scheermesser prepared a pepsin-peptone 

 having very similar properties : 



If the simple formula be taken, it is a monobasic acid. Scheermesser 

 has examinefd the zinc and the barium salts : 



a D =-77-5. 



The furfurol- and the glyoxylic-acid reactions give negative results. 



The relation of Pick's peptones to the pure peptones of Siegfried 

 is not known, nor whether other peptones exist besides those enumer- 

 ated above. Pfaundler 1 describes an ether -soluble peptone which 

 was precipitated by metallic salts and the alkaloidal reagents, and 



1 M. Pfaundler, Zeitschr. f. physiol. Chem. 30. 90 (1900). 



