484 DIGESTION. 



white, against the action of trypsin is remarkable a behavior which 

 can be explained by the occurrence of anti-bodies in these solutions 

 and which HEDIN 1 has carefully studied. An accumulation of the prod- 

 ucts of indigestion tends to hinder the trypsin digestion. 



An interesting contrast to the inactivity of trypsin toward native egg- 

 'albumin and seralbumin is the enzyme papain, which, as the investigations of 

 DELEZENNE, MOUTON and POZERSKI and of JONESCU and SACHS 2 have shown, 

 is hindered in its action by an anti-body in the albumin which is destroyed by heat 

 or by the action of acid. 



The Products of the Tryptic Digestion. In the digestion of unboiled 

 fibrin a globulin which coagulates at 55-60 C. may be obtained as an 

 intermediate product (HERRMANN 3 ) . Besides this one obtains from 

 fibrin, as well as from other proteins, the products previously mentioned 

 in Chapter III. In trypsin digestion the cleavage may proceed so far 

 that the mixture fails to give the biuret reaction. This does not indicate, 

 <as E. FISCHER and ABDERHALDEN have shown, a complete cleavage of the 

 protein molecule into mono- and diamino-acids, etc. In tryptic diges- 

 tion, as shown by ABDERHALDEN and REINBOLD, using the protein edestin, 

 and by ABDERHALDEN and VoEGTLiN, 4 with casein, a gradual cleavage of 

 the protein takes place, and thereby certain amino-acids, like tyrosine and 

 tryptophane, are readily and completely split off, while others, like 

 leucine, alanine, aspartic acid, and glutamic acid, are slowly and less 

 readily split off, and others, such as a-proline, phenylalanine, and gly- 

 ^cocoll, stubbornly resist the cleavage action of the trypsin. The poly- 

 peptide-like bodies discovered by FISCHER and ABDERHALDEN, which 

 are produced in digestion, and which do not give the biuret reaction, 

 &re the atomic complexes which resist the action of trypsin. These 

 peptoids contain the pyrrolidine carboxylic acid and phenylalanine 

 groups of the protein, but also yield other monamino-acids such as leu- 

 cine, alanine, glutamic acid, and aspartic acid. Among the above- 

 mentioned products we find on the autodigestion of the gland other sub- 

 stances, such as oxyphenylethylamine (EMERSON), which is produced 

 from tyrosine by fermentive C02 cleavage, also uracil (LEVENE), guani- 

 dine (KUTSCHER and OTORI), the purine bases, which originate from the 

 nuclein bodies, and choline, which latter is formed from lecithin (KUT- 

 SCHER and LoHMANN 5 ). If putrefaction is not completely prevented, 



1 See Zeitschr. f. physiol. Chem., 50, where the works of Hedin are cited. 



2 Delezenne, Mouton and Pozerski, Compt. rend., 142; Jonescu, Bioch. Zeitschr., 

 2, Sachs, Zeitschr. f. physiol. Chem., 51. 



3 Herrmann, Zeitschr. f. physiol. Chem., 11. 



4 Abderhalden and Reinbold, Zeitschr. f. physiol. Chem., 44 and 46, with Voegtlin, 

 ibid. 53. 



5 Fischer and Abderhalden, Zeitschr. f. physiol. Chem., 39; Emerson, Hofmeister's 



