v PEPTONES 195 



These peptones resemble the pepsin -peptones in being pronounced 

 acids ; they are monobasic if we adopt the simple formula, but the latter 

 must be multiplied because of the dissociation-compounds which are 

 formed. 



The zinc and barium salts of these anti-peptones have been analysed. 

 Their behaviour towards precipitants is the usual one described above ; 

 amongst colour-tests, positive results are only obtained with the biuret 

 and the xanthoproteic reactions. Anti-peptones are laevo-rotatory : 



Anti-peptone a a^= -24-5. 



Anti-peptone /? . ' . . . , 4=-32'4. 



The salts are more strongly Isevo-rotatory. 



Anti-peptone a on being dissociated with acids gives rise to lysin, 

 arginin, 4 per cent ammonia, 1 2 per cent glutaminic acid, aspartic and 

 other amino-acids. Anti-peptone /? yields lysin, arginin, 3 per cent 

 ammonia, and glutaminic acid. The bases account for only one-quarter 

 the amount of nitrogen, and therefore mono -amino-acids must be 

 abundantly present. 



Gelatine, on tryptic digestion, gives rise to an anti-peptone : 

 C 19 H 30 N 6 9 (C 46-74 ; H 6-2 ; N 17'36 per cent) 

 a D = - 100-8. 



In other respects it resembles the anti-peptones a and /3 ; on being 

 boiled with acids it yields lysin, arginin, glutaminic acid, and glycocoll. 

 On being carefully dissociated with acids, a base is obtained which is 

 perhaps identical with kyrin, see p. 200. 



Kriiger describes yet another peptone with a D = - 64 -3. 



The fibrin-anti-peptones are not only formed directly from albumin, 

 but may also be obtained, along with tryptophane, tyrosin, and arginin, 

 by the tryptic digestion of pepsin-peptones. 



From sturin Kossel and Matthews 1 prepared a trypsin-peptone, 

 having the composition C 18 H 35 N 7 5 , the silver salt of which crystallised 

 well, and was therefore a pro tone (see p. 423). 



From silk-fibroin E. Fischer and Bergell 2 obtained, by tryptic 

 digestion, after a preliminary partial dissociation with acids, a laevo- 

 rotatory peptone having the composition C 40 . 6 H 6 . 6 N 18 . 4 , which on being 

 dissociated with acids yielded 40 -1 per cent glycocoll, 2 8 -5 per cent 

 alanin, and no tyrosin. Treatment with alkali gave rise to the di- 

 peptid glycyl-alanin. 



The pancreas-peptones used to be called tryptones by Fano. 3 



1 A. Kossel and A. Matthews, Zeitschr. /. physiol. Chem. 25. 190 (1898). 



2 E. Fischer, Chemikerztg. 1902, II. p. 939. 

 3 Fano, Arch.f. (Anat. u.) Physiol. 1881, p. 277. 



