486 



EFFECT OF ENZYME ON DIGESTION OF PROTEINS 



Fig. 4 where the straight line represents the concentration of active 

 pepsin which would be present if the combination was complete. 

 Table VI also shows that the first unit of peptone inactivates more 

 pepsin than the second, etc. This phenomenon is also common in 

 immunology and is known as Ehrlich's phenomenon. As Arrhenius^^ 

 has pointed out it is a general property of any equilibrium system. 



0.85 



6.6 



1.7 3.4 5.1 



Units of peptone added 



Fig. 4. Curves showing effect of adding increasing amounts of peptone to 

 pepsin solutions (c/. Table VI) . 



In several other respects the action of pepsin on an egg albumin 

 solution is more or less analogous to the action of toxin on an organism. 

 In a sense the pepsin may be said to make the egg albumin solution 

 immune to pepsin. That is, if a small amount of pepsin is allowed to 

 act for a long time on a large quantity of albumin it will at first digest 

 it very rapidly and the rate of digestion will be proportional to the 

 amount of pepsin added. The rate of digestion decreases rapidly, 



^* Arrhenius, S., Ergebn. Physiol., 1908, vii, 480. 



