2a 



[From THE BIOCHEMICAL JOURNAL, Vol. XIII, No. 2, July, 1919] 



THE EFFECT OF ALCOHOL ON THE DIGESTION 

 OF FIBRIN AND CASEINOGEN BY TRYPSIN. 



By EDWAKD STAFFORD EDIE. 



From the Physiological Department, 



{Received May 19th, 1919.) 



The behaviour of extracts of pancreas or pure pancreatic juice under different 

 conditions has led various observers to conclude that the pancreas contains a 

 number of proteolytic enzymes. It was shown by Fermi [1890] that after treat- 

 ment with mercuric chloride, salicylic acid and various other substances, 

 trypsin lost its power of digesting fibrin but would still digest gelatin, Vernon 

 [1901] arguing from the varying sensitiveness of pancreatic extracts towards 

 sodium carbonate, concluded that "trypsin" was really a mixture of enzymes 

 of different degrees of stability, the more sensitive enzymes being destroyed 

 first. Vernon only tested the digestive power of trypsin on raw fibrin in this 

 connection however. In a later paper Vernon [1903, 2] states that pancreatic 

 extracts contain an erepsin as well as trypsin. Pollak [1905] using different 

 preparations of enzymes found that the relative amounts of serum and gelatin 

 digested varied enormously in different cases. He also found that after treat- 

 ment with hydrochloric acid trypsin lost its power of acting on serum, but 

 was still about as active as ever on gelatin. Pollak concluded that extracts of 

 pancreas contained in addition to trypsin (to which the action on serum was 

 due) a special enzyme which acted only on gelatin. To this enzyme Pollak 

 gave the name of glutinase. 



According to Ascoli and Neppi [1908], however, this assumption of a 

 special enzyme acting on gelatin is unjustified, as they find that slight varia- 

 tions in the reaction of the medium affect the digestion of different proteins 

 to different degrees. Mays [1906] after a long series of experiments remarks 

 that the presence of two proteolytic enzymes in pancreatic extracts can only 

 be proved when it is possible to make a separation of the enzymes. It had 

 been previously shown by Bayfiss and Starling [1903] that pancreatic juice as 

 secreted contains no trypsin (as tested on coagulated egg white), but contains 

 a weak enzyme hke erepsin. This has some action on caseinogen, but very 

 slight. The erepsin has a slight action on fresh fibrin but practically none on 

 fibrin which has been heated to 70°. It may here be mentioned that Long and 

 Barton [1914] state that raw fibrin even when very carefully purified may 

 soon become liquid owing to autolysis. 



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