PRODUCTS OF PANCREATIC DIGESTION. l8l 



tone under the influence of trypsin. But the amphopeptone 

 contains some of the hemi group also and this under energetic 

 pancreatic action finally yields crystalline products no longer 

 capable of giving the biuret reaction. The anti group as 

 finally found in the antipeptone was long supposed to be a 

 permanent end product, not subject to further digestive 

 change. But this view seems to be erroneous. It has been 

 already stated that pancreatic digestion as distinguished from 

 peptic digestion may be carried so far that nothing is left 

 which gives the biuret reaction. When the peculiar group on 

 which this reaction depends drops out, the whole molecular 

 structure is so badly shattered that nothing which may be con- 

 sidered as closely related to the proteins remains. 



The question then comes up, what are the final products of 

 tryptic action? Numerous investigations of comparatively 

 recent date give us more or less satisfactory answers to this 

 question. 



Carnic Acid. From a number of sources, particularly from 

 beef extract, Siegfried has obtained a product which he calls 

 carnic acid and which seems to have a constant composition 

 represented by the formula, C 10 H 15 N 3 O 5 . In the muscles and 

 in milk this acid is held to exist in combination with phos- 

 phorus in the so-called phosphocarnic add, the iron combina- 

 tion of which is known as carniferrin. The true carnic acid 

 gives the biuret reaction, but the Millon reaction only faintly. 

 It forms crystalline salts with copper, barium, zinc and other 

 metals. Its solutions are precipitated by phospho-tungstic 

 acid, tannic acid and picric acid, but not by ammonium 

 sulphate. 



Siegfried considers this carnic acid as identical with anti- 

 peptone, and a large number of papers have been published in 

 support of the theory. The carnic acid must be made up of 

 groups still holding the biuret complex, in which leucine, tyro- 

 sine, the hexone bases and perhaps other bodies are all joined 

 in some way not yet understood. 



The Hexone Bases and Other Bodies. The Siegfried 



