ACTION OF THE ENZYMES. 133 



The curve representing the decrease in the viscosity of a 

 protein solution can be expressed mathematically when it 

 becomes possible to calculate the relations which exist be- 

 tween the velocity of digestion and the amount of pro- 

 teolytic ferment present. 



7. Antiproteinase (antipepsin and antitrypsin). Under the 

 heading antiproteinase we understand a substance discovered 

 by WEINLAND,! which has the power of markedly inhibiting 

 by its presence the action of the proteolytic enzymes. Anti- 

 proteinase is therefore one of the so-called antiferments. 

 Antiproteinase can be obtained from a number of sources 

 the mucous membrane of the stomach and intestines, but, 

 best of all, from various intestinal worms, especially ascaris. 

 A description of the method by which antiproteinase can be 

 obtained from ascaris will suffice to indicate the method by 

 which, in general, this substance can be obtained from any of 

 the tissues or fluids in which it is present (see below). 



A very active though impure preparation of antiproteinase 

 can be obtained by simply grinding up a number of the intes- 

 tinal worms with quartz sand. The addition of this ground-up 

 mass to an acid-proteinase or alkali-proteinase solution 

 markedly inhibits the activity of these ferments. A better 

 preparation of the antiproteinase can be obtained by sub- 

 jecting the ascaris paste to great pressure and collecting 

 and filtering the fluid which is squeezed out. The anti- 

 ferment contained in this very active juice can be further 

 purified by adding alcohol to it, whereby the antiproteinase is 

 precipitated as soon as the concentration of the alcohol in the 

 mixture exceeds 85 percent. The substances (impurities) 

 which are precipitated before the concentration of the alcohol 

 reaches 60 percent may be filtered off without danger of 

 losing the antiproteinase. The precipitate of antiproteinase 

 brought down by the 85 percent alcohol settles to the bottom 



I WEINLAND: Zeitschr. f. Biologie, 1902, XLIV, p. 1; ibid., 1902, 

 XLIV, p. 45. 



