416 CHEMISTR Y OF THE DIGESTIVE PROCESSES. 



the properties of a globulin, but in the case of serum albumin no such 

 formation of a globulin takes place. 1 If the proteid employed has 

 previously been coagulated, no formation of a coagulable proteid is 

 observed, the first product being apparently deuteroalbumose. 2 



The appearances presented by proteid undergoing solution by the 

 action of pepsin and of trypsin respectively, are characteristically 

 different. In the case of pepsin and hydrochloric acid, the proteid 

 swells up, becomes transparent or translucent, and gradually dissolves ; 

 while, by the action of trypsin in alkaline solutions, the proteid does not 

 swell up or become clearer, but is attacked and eroded from the outside. 



After being dissolved, the proteid is further attacked by the trypsin 

 and decomposed into various products, the final result being a certain 

 amount of peptone which is not further acted on, accompanied by 

 various nitrogenous bodies, of which those occurring in largest quantity 

 are two amido-acids, leucine and tyrosine. 



The primary albumoses of peptic digestion are not found among the 

 intermediate products of tryptic digestion. No matter at what stage 

 digestion is interrupted, no trace of either proto- or heteroalbumose is 

 found ; the only albumose present is deuteroalbumose. 3 



IS T eumeister suggests that this may be due to the protoalbumose being 

 broken up as rapidly as it is formed into amido-acids, while the heteroalbumose 

 is immediately converted into deuteroalbumose. Be this as it may, the 

 experimental fact is, that neither protoalbumose nor heteroalbumose are 

 found at any stage of tryptic digestion. 



According to Neumeister, the deuteroalbumose present is an anti-compound 

 not yielding any amido-acids when subjected to the further action of trypsin. 4 



Peptone is formed much more rapidly in tryptic than in peptic 

 digestion, the preliminary stages being apparently rushed through ; while 

 in peptic digestion scarcely any peptone is formed before complete 

 conversion into albumoses has taken place, and complete peptonisation 

 never occurs. 



The most essential difference between the digestive action of trypsin 

 and that of pepsin lies in the discovery of Kiihne, that the action of 

 the former enzyme does not cease with the formation of peptone, but 

 that approximately one-half of the proteid, or of the peptone formed 

 from it, is converted into a number of cystalline substances of much 

 simpler composition. 



Not only does this take place in the direct tryptic digestion of proteids, 

 but if peptone formed by peptic digestion be submitted to tryptic 

 digestion, about one-half of it is decomposed in the above fashion. This 

 experiment led Kiihne to the cleavage theory, and to naming, on the 

 basis of this theory, the peptone of peptic digestion, fcmjpAopeptone ; the 

 peptone remaining after the completion of tryptic digestion, and which 

 is no longer affected by renewed digestion, ew^ipeptone; and that 

 hypothetical substance which is supposed to form one moiety of the 

 amphopeptone, and be broken up by the action of the trypsin, 



1 Neumeister, Ztschr. f. Biol., Munchen, 1887, Bd. xxiii. S. 398 ; ibid., 1890, Bd. xxvii. 

 S. 311 ; Herrmann, Ztsclir. f. physiol. Chem., Strassburg, 1887, Bd. xi. S. 521. 



2 When trypsin acts in an alkaline medium, alkali albumin is first formed ; but this is a 

 very transient stage, the alkali albumin being quickly changed into deuteroalbumose. 



3 Otto, Ztschr. f. physiol. Chem., Strassburg, 1883, Bd. viii. S. 129; Neumeister, 

 Ztschr. f. Biol., Munchen, 1887, Bd. xxiii. S. 398. 



4 Ztschr. f. BioL, Munchen, 1887, Bd. xxiii. S. 381. 



